[155-mm Howitzer Motor Carriage, M41]
[From the U.S. Government Publishing Office, www.gpo.gov]
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WAR DEPARTMENT TECHNICAL MANUAL
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155-mm HOWITZER
MOTOR CARRIAGE
M41
U ofNT LIBRARIES
76203
GIFT
WAR DEPARTMENT • SEPTEMBER 1947
WAR D E PA R T M E N T TECHNICAL MANUAL
TM 9-744
This manual supersedes so much of TB ORD 20, 24 January 1944; TB ORD 126, 19 July 1944; TB 9-729-1, 5 September 1944; and TB 9-729-5, 24 April 1945, as pertains to the materiel covered in this manual.
155-mm HOWITZER
MOTOR CARRIAGE
M41
WAR DEPARTMENT . SEPTEMBER 19 47
United States Government Printing Office Washington : 1947
WAR DEPARTMENT
Washington 25, D. C., 17 September 1947
TM 9-744, 155-mm Howitzer Motor Carriage, M41, is published for the information and guidance of all concerned.
The information in this manual is correct as of 1 May 1947.
[AG 300.7 (7 Jan 47)]
By order of the Secretary of War :
Official: DWIGHT D. EISENHOWER
EDWARD F. WITSELL Chief of Staff
Major General
The Adjutant General
Distribution :
AAF (5) ; AGF (2) ; T (10) ; Dept (5) ; Arm & Sv Bd (1) ; Tech Sv (2) ; FC (1) ; PE (Ord O) (5) ; Gen Dep (Ord Sec) (1) ; Dist 9 (3) ; Establishments 9 (3) ; Gen & Sp Sv Sch (5) ; Tng Ctr (2); A (ZI) (25), (Overseas) (3) ; CHQ (2) ; D (2) ; One (1) copy to each of the following T/O & E’s: 6-437; 9-7; 9-9; 9-65, 9-67; 9-197; 9-316; 9-317; 9-325.
For explanation of distribution formula, see TM 38-405.
II
CONTENTS
PART ONE . INTRODUCTION Paragraphs Page
Section I. General_________________________________________ 1-2 1
II. Description and data____________________________ 3-4 3
PART TWO . OPERATING INSTRUCTIONS
Section III. General___________________________________________ 5 10
IV. Service upon receipt of equipment_______________ 6-9 10
V. Controls and instruments______________________ 10-12 15
VI. Operation under ordinary conditions___________ 13-18 25
VII. Mount controls and operation__________________ 19-20 29
VIII. Operation of auxiliary equipment______________ 21-22 34
IX. Operation under unusual conditions____________ 23-26 37
X. Demolition to prevent enemy use______________ 27-28 42
PART THR EE. MAINTENANCE INSTRUCTIONS Section XI. General_________________________________________________ 29 46
XII. Special organizational tools and equipment_ 30-31 46
XIII. Lubrication___________________________________ 32-33 49
XIV. Preventive maintenance services_______________ 34-40 61
XV. Trouble shooting______________________________ 41-55 90
XVI. Engine description and maintenance in vehicle. 56-66 114
XVII. Engine removal and installation_______________ 67-68 129
XVIII. Ignition system_______________________________ 69-75 141
XIX. Starting system_____________________________ 76-79 149
XX. Generator and charging system_________________ 80-82 152
XXI. Battery and lighting system___________________ 83-87 156
XXII. Instruments and Instrument panel______________ 88-93 164
XXIII. Miscellaneous electrical equipment__________ 94-103 166
XXIV. Radio interference suppression______________ 104-107 173
XXV. Fuel and air intake and exhaust Systems_____ 108-113 178
XX VI. Cooling system________________________________ 114-119 191
XXVII. Hydramatic transmissions____________________ 120-125 203
XXVIII. Propeller shafts and support bearings_______ 126-128 210
XXIX. Transfer unit_______________________________ 129-132 213
XXX. Controlled differential_____________________ 133-138 220
XXXI. Final drive_________________________________ 139-141 229
XXXII. Tracks and suspension______________________ 142-153 232
XXXIII. Hull________________________________________ 154-166 251
XXXIV. Fire extinguisher_______________________________ 167 260
III
PART FOUR. AUXILIARY EQUIPMENT
Section XXXV. General____________________________________ 168 262
XXXVI. Armament______________________________ 169-171 262
XXXVII. Armament operating instructions______ 172-179 264
XXXVIII. Sighting and fire control equipment___ 180-183 274
XXXIX. Ammunition___________________________ 184-187 279
XL. Radio and interphone equipment_________ 188-192 290
APPENDIX I. SHIPMENT AND LIMITED STORAGE________________ 298
II. REFERENCES_____________________________________ 303
INDEX__________________________________________________________ 308
IV
This manual supersedes so much of TB ORD 20, 21, January 191,1,; TB ORD 126, 19 July 191,1,; TB 9-729-1, 5 September 191,1,; and TB 9-729-5, 21, April 191,5, as pertains to the materiel covered in this manual
PART ONE INTRODUCTION
Section I. GENERAL
1. Scope
a. These instructions are published for the information and guidance of all concerned. They contain information on operation and maintenance of the equipment as well as descriptions of the major units and their functions in relation to other components of this vehicle. They apply only to the 155-mm howitzer motor carriage M41 and are arranged in four parts: Part One, Introduction; Part Two, Operating Instructions; Part Three, Maintenance Instructions; Part Four, Auxiliary Equipment and Appendix.
&. The appendix at the end of the manual contains instructions for shipment and limited storage, and a list of references including standard nomenclature lists, Technical Manuals, and other publications applicable to the vehicle.
2. Records
a. General. Forms, records, and reports are designed to serve necessary and useful purposes. Responsibility for the proper execution of these forms rests upon commanding officers of all units operating and maintaining vehicles. It is emphasized, however, that forms, records, and reports are merely aids. They are not a substitute for thorough practical work, physical inspection, and active supervision.
Z>. Authorized Forms. The forms, records, and reports generally applicable to units operating and maintaining these vehicles are listed below with brief explanations of each. Only approved War Department forms will be used in operating and maintaining the vehicles. Pending availability of forms listed, old forms may be used. For a current and complete listing of all forms, see current FM 21-6.
(1) War Department Lubrication Order. War Department Lubrication Order No. LO 9-744 prescribes lubrication maintenance for this vehicle. A lubrication order is issued with each vehicle and will be carried with it at all times. Instructions contained therein
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are mandatory to all users of the equipment and supersede all conflicting lubrication instructions of prior date.
(2) Standard, Form, 26 {Driver's Report—Accident, Motor Transportation). One copy of this form will be kept with vehicle at all times. In case of an accident resulting in injury or property damage, it will be filled out by the driver on the spot or as promptly as practicable thereafter.
(3) War Department Form 30 {Report of Claims Officer). This form will be used by the claims officer in reporting his investigation of vehicle accidents.
(4) War Department Form J8 {Driver's Trip Ticket and Preventive Main tenance Service Record). This form, properly executed, will be furnished driver or operator when his vehicle is dispatched on non-tactical missions. The driver and the official user of the vehicle will complete in detail appropriate parts of this form. This form need not be issued for vehicles in convoy or on tactical missions. The reverse side of this form contains the driver’s daily and weekly preventive maintenance service schedule, the accomplishment of which is mandatory.
(5) War Department AGO Form 9-69 {Spot Check Inspection Report for AU Full-Track and Tank-Like Wheeled Vehicles). This form is provided as a record for use by commanders and their staff representatives conducting command inspections on this type of equipment.
(6) War Department AGO Form 9-71 {Locator and Inventory Control Card). Except when specified otherwise by the War Department, this form will be used as a bin tag, locator card, or inventory control card by all units authorized automotive spare parts.
(7) War Department AGO Form 9-73 {Data for Registration). All vehicles will be registered in the War Department Motor Vehicle Central Records Office; Office, Chief of Ordnance, Washington 25, D. C. Attn:ORDFQ. Registration will be made by accomplishing this form in accordance with AR 850-10.
(8) War Department AGO Form 9-74 {Motor Vehicle Operator's Permit). This form will be issued by commanders to all operators of vehicles who are qualified to operate the particular vehicles noted on the permit.
(9) War Department AGO Form 9-75 {Daily Dispatching Record of Motor Vehicles). This form will be used to keep a daily record of all vehicles dispatched.
(10) War Department AGO Form 9-76 {Request for Work Order). This form will be used for requesting repairs, alterations, or other type of work within or between organizations and departments.
(11) War Department AGO Form 9-77 {Job Order Register). This form will be used to keep a chronological record of work orders.
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(12) War Department AGO Form 13-1 {Automotive Disability Report of Vehicles Disabled More Than Three Days}. This form will be accomplished and submitted as directed in current War Department instructions.
(13) Wdr Department AGO Form IfiO {Preventive Maintenance Roster}. This form will be used for scheduling and maintaining a record of motor vehicle maintenance operations (weekly, monthly, quarterly, and semiannually).
(14) War Department AGO Form IflZ (Work Sheet for Full-track and Tank-Like Wheeled Vehicles}. This form will be used for maintenance services and for all technical inspections of these vehicles.
(15) War Department AGO Form Jfl8 {Modification Work Order and Major Unit Assembly Replacement Record and Organization Equipment File}. This form will be kept in possession of second echelon personnel and will accompany vehicles upon transfer and evacuation to higher echelon. It will be a record of all modifications made and exchanges of major unit assemblies. Minor repairs, parts, and accessory replacements will not be recorded. In the field, where no filing facilities are available, this form will be kept in a filing jacket.
(16) War Department AGO Form IRU {Monthly Motor Vehicle Accident Summary Report}. This form will be used to furnish a monthly summary of accidents involving vehicles.
(17) War Department AGO Form 811 {Work Request and Job Order}. This form will be used by organizational maintenance units when requesting repair by a higher echelon repair unit.
Section II. DESCRIPTION AND DATA
3. Description
a. General. The 155-mm howitzer motor carriage, M41, is an armored, full-track laying, self-propelled mount for a 155-mm howitzer. It carries 5 of the 12 men who comprise the crew. Of the 5 men carried, 2 travel in the driving compartment and 3 in seats on the gun mount. The vehicle is designed with a driving compartment at the front, an engine compartment in the center, and a fighting compartment at the rear, above which the howitzer mount is assembled. Dual controls are provided for the driver and for emergency operation of the vehicle by the assistant driver.
b. Power Train. The vehicle is driven by two Cadillac, 8-cylinder, 90°, V-type, liquid-cooled engines, through two hydramatic transmissions; a transfer unit with mechanically selected speed ranges, two forward and one reverse; a controlled differential for steering and braking, which is located in the front of the hull; two final drives; and the necessary connecting propeller shafts. Wide steel block tracks provide the means of propulsion. Torsion arm suspension is used for
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the dual track wheels, and includes a compensating wheel at the rear on each side to keep track tension more nearly uniform on rough terrain.
c. Hull. The hull of this vehicle is a completely welded structure, except for portions of the front, top, and floor, which are removable for service operations. The hull is divided into three compartments: The driving compartment at the front, the engine compartment in the center, and the fighting compartment at the rear, above which is mounted the 155-mm howitzer. The driving and engine compartments are separated by a bulkhead that extends from side-to-side, and from the roof down to the bulkhead extensions, which in turn extend forward far enough to cover the transfer unit. The engine and stowage compartments are separated by a bulkhead that extends from side-to-side and from roof-to-floor. A spade and gunner’s platform assembly is hinged to brackets mounted on the hull at the rear of the vehicle. When the spade and platform assembly is in the raised position it serves as a tailgate. The spade and platform assembly in the lowered position provides a platform for the gunner and the spade acts as an anchor to keep the vehicle in position when the gun is fired. The spade assembly is raised and lowered by a hand operated winch. The front of the hull slopes downward at the top and upward at the bottom to form a V. The sides of the hull slope inward at the bottom. Lifting eyes are provided and should always be used when the vehicle is to be lifted.
d. Howitzer. The howitzer, mount, and shielding are mounted at the rear of the vehicle. The mount provides 5° depression, 45° elevation, 20^° right traverse and 17° left traverse.
4. Tabulated Data
a. General.
Purpose_______________________________________Mobile artillery.
Type__________________________________________Full-track laying.
Crew--------------------------------------------------- 12 men.
Weight (with fuel, ammunition, and crew)______________ 42,500 lb.
Length___________________________________________________ 230 in.
Width---------------------------------------------------- 112 in.
Height, over-all___________________________________________96 in.
Ground clearance__________________________________________17% in.
Ground pressure at 1-inch penetration__________________8.816 psi.
b. Maximum Operating Characteristics.
Sustained speed________________________________________30 mph.
Grade, ascending or descending___________________________60 pct.
Width of ditch______________________________________________9 ft.
Vertical obstacle__________________________________________40 in.
Fording depth----------------------------------------------42 in.
4
FENDER STOWAGE BOX
155-MM HOWITZER SHIELD STOWAGE BOX —v / ,
HULL VENTILATOR — \
ASSISTANT DRIVER'S DOOR
FRONT COVER PLATE . J
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zjjA^Z>
PERISCOPE AND GUARD /
DRIVER'S DOOR-/ "^~ COMPENSATING WHEEl—l
DRIVE SPROCKET—/ ** [
TRACK WHEEL— TRACK support ROLLER
Figure 1. 155-mm Howitzer motor carriage, M41, three-quarter left front view.
155-MM
SPADE
HOWITZER. ~ _ „,, ---• ... .......x-
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LOCK_\ v_
PLATFORM AND SPADE WINCH
SHIELD STOWAGE BOX
WATER BUCKET
PIONEER TOOLS
SPADE TRAVEL
WINCH SHAFT
RA PD 331924
Figure 2. 155-mm Howitzer motor carriage, Mlfl, three-quarter right rear view.
5
ASSISTANT RIGHT ENGINE DOOR— ANTENNA BASE
DRIVER S DOOR GAS0UNE TANK F|lLER \ SHIELD STOWAGE / HEADLIGHT BATTERY COVER I \ BOX / /-SIREN SPADE AND PLATFORM
v- rltADLIOnl I H 9 WINCH
\ ll I 11 GUNNER’S -FORM
f -J “ 6lF
4 , ft) . \ r A R I ....
■ ,J ' ijliiiiii . miiiiijig.RAMMER STAFF
..............'--— —---------. -. / A A /Ar- 'SS (‘ h « - -----|
j i R \ Wo^yte ■ k. v \ x LEFT ENGINE DOOR / BOX \ \ \— SHIELD STOWAGE BOX
ATTERY COVER _/ \_ RADIATOR COMPARTMENT \_ GASOLINE TANK FILLER
Fiaure. 3. 155-mm Howitzer motoi carriage, MAI, top view.
CO
6
155 MM. HOWITZER CARBURETOR AIR CLEANER __ rfHh—-----—A
TRANSMISSION \ RADIATOR - H________~^. Refer deficiencies beyond the scope of organizational maintenance to Ordnance maintenance personnel for correction.
10
c. Bring deficiencies of a serious nature to the attention of the supplying organization through proper channels.
8. Specific Procedures
a. Preliminary Service. Before the vehicle is moved to make actual run-in test, certain inspections and services will be performed as follows:
b. Inspections and Services (1) Fire extinguishers. See that the portable- and fixed-system cylinders are securely stowed. Inspect the operating valves. If the valves appear to have been opened or damaged, report to proper authorities for exchange or refill. Examine the lines, nozzles, and control cables of the fixed system to see that they are in good condition and that the nozzles are not clogged.
(2) Fuel, oil, and 'water. Fill fuel tanks. Check level of coolant in radiator and add as necessary to bring to correct level. Allow room for expansion in fuel tanks and radiators. During freezing weather, test strength of antifreeze and add as necessary to protect system against freezing. Check level of oil in each engine. Caution: If there is a tag attached to the crankcase filled caps concerning engine oil in crankcases, follow instructions on tags before driving vehicle.
Note. Vehicles shipped from depots may have white unleaded gasoline in the tanks. This should be drained and 80 octane used for filling.
(3) Fuel strainer. Inspect the fuel strainer at each carburetor inlet elbow for leaks or damage. Remove strained bowl and clean out any accumulation of foreign matter. Be sure that both fuel switches and shut-off valves operate properly. Drain accumulated dirt and water from bottom of fuel tanks. Drain only until fuel runs clean.
(4) Batteries. Remove battery covers and clean any accumulated dust or dirt from tops of batteries. Make hydrometer and voltage test of batteries and if necessary, add distilled or clean water to bring electrolyte to inch above plates.
(5) Air cleaners and breathers. Examine carburetor air cleaners and chankcase breather cleaners to see that they are in good condition and secure. Remove air-cleaner elements, wash in dry-cleaning solvent, and fill reservoirs with oil to the correct level as directed in lubrication order (par. 32), Reinstall securely, and make sure all connections are in good condition and ducts and air-horn connections are tight.
(6) Accessories and belts. See that accessories such as carburetor, generators, regulators, distributors, starters, water pumps, and fans on both engines are securely mounted and that drive belts are in good condition and adjusted with %- to %-inch, finger-pressure deflection (fig. 50).
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(7) Electrical wiring. Inspect all accessible wiring and conduits to see that these parts are in good condition, securely connected and properly supported.
(8) Tracks. Clean all foreign material from tracks and suspension units. Examine track blocks for damage and for loose or damaged nuts and screws. See that tracks are correctly assembled and mounted and that tension is adjusted so that there is %- to 1-inch sag between the second and third support rollers (fig. 128).
(9) Wheel and flange nuts. See that operating compensating wheel, track wheel, sprocket, and support roller assembly mounting and flange nuts are present and secure.
(10) Fenders and shields. See that fender brush guards and sandshields (if so equipped) are in good condition and secure and that shield hinges operate properly.
(11) Towing connections. Examine towing loops, pintles, and gun traveling lock for looseness and damage. Be sure that pintle hook and gun traveling lock operate properly and lock securely.
(12) Hull and tarpaulin. See that all hull attachments, hardware, lift loops, doors and their releases and locking mechanisms, are in good condition, secure, and operating properly. Examine all hull and gun mount attachments for looseness and damage. Be sure hull drain valves open and close freely. Inspect tarpaulin or camouflage net to see that these items are in good condition, and mount or stow them securely. Make sure there are no bright spots to cause glare, and that all markings are legible.
(13) Vision devices. Inspect periscope prisms' and windows (mounted or spares) to see that they are in good condition and clean. See that mounted units are secure in holders, and that holders are properly mounted. Test each periscope to be sure it will elevate, traverse, and depress through full range.
Caution: Clean periscope only with a soft cloth or brush.
(14) Lubrication. Perform a complete lubrication of the vehicle, covering all intervals according to instructions in the lubrication order except gear cases and units lubricated or serviced in items (1) to (13). Check all gear case oil levels and add as necessary to bring to correct levels; change only if condition of oil indicates the necessity, or if oil is not of proper grade for existing atmospheric temperature.
Rote. Perform items (15) to (18) during lubrication.
(15) Suspensions. Examine all suspension arms, brackets, shock absorber links, and guides to see if they are in good condition, correctly assembled, secure, and not leaking excessively at seals. Inspect sprocket teeth for damage or excessive wear. Be sure road wheel and support roller tires are in good condition and that rubber is not separating from rims. While applying lubrication, examine seals for excessive leaks.
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(16) Steering linkage. Inspect all shafts, arms, rods, connections, levers, and grips to see if they are in good condition, correctly and securely assembled and mounted, and that they operate without excessive looseness or binding. Check brake linkage adjustment by pulling back evenly to make sure free travel is equal and does not exceed six notches, and that brakes are fully applied within three additional notches (par. 134). Be sure parking brake mechanism locks the brake properly in the locking position.
(17) Propeller shafts. Remove all propeller shaft covers, and inspect shafts and universal joints to see if they are in good condition, correctly assembled, alined, secure, and not leaking excessively at seals.
(18) Choke. Before starting engines, see that choke operates freely (fig. 94). When starting engines in item (19), observe if action of automatic choke is satisfactory. Adjust choke setting, if necessary, according to instructions (par. 110).
(19) Engine warm-up. Start engines, noting if cranking motor action is satisfactory, and any tendency toward difficult starting, inadequate cranking speed, or unusual noise. Set hand throttle to idle engines at 625 revolutions per minute during warm-up.
(20) Instruments, (a) Warning signals. Do not drive vehicle while engine or transmission warning signals are lighted.
(&) Ammeter. Ammeter should show slight positive ( + ) charge at engine speeds above 1,400 revolutions per minute. High charge may be indicated until generator restores to battery current used in starting.
(»
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Figure 5. Master battery switch.
b. Ignition Switches. The ignition switches are located in the lower right corner of the instrument panel (fig. 6). The switch on the right-hand side controls the engine on the right-hand side of the hull, and vice versa. When ignition switches are turned on, the engine and transmission low oil pressure warning lights will be illum-
ENGINE TEMPERATURE GAGES—,
PANEL LIGHT \-PANEL LIGHT ACCESS PLUGS; t^NC STARTER
SWITCH SPEEDOMETER / j 7 .^BUTTONS
fwlipMBk ZO
/ V c V/ v < W:
/WARNING V-CIRCUIT BREAKER \ V AMMETER \ IGNITION^
SIGNALS RESET BUTTONS \-TACHOMETERS-^ SWITCHES
Figure 6. Instrument panel.
16
inated. An “emergency ignition” switch is located on the hull roof slightly to the right and rear of the driver (fig. 12).
Note. The wiring is so arranged (in series) that this “emergency ignition” switch must be kept in the ON position; otherwise, the ignition circuit will be open even though the instrument panel switches are “ON.”
c. Fuel Pump Controls. The fuel pump controls consist of two levers mounted on the front deck to the right of the driver above the controlled differential (fig. 7). The left-hand lever controls the fuel shut-off valve and the power feed to the fuel pump in the left-hand fuel tank, and the right-hand lever controls the same devices for the right-hand tank. When the levers are moved down, the fuel valves are open, and the current to the fuel pumps is “ON.” When the levers are moved up, the valves are closed and the pumps are turned off. The two levers can be turned on or off independently.
Note. At least one of the ignition switches must be turned on to complete the power feed circuit to the fuel pumps.
d. Starter Buttons. The two starter buttons are located in the lower right side of the instrument panel (fig. 6). Start both engines at the same time (except in extremely cold weather) by pressing both starter buttons.
e. Lighting Switches. (1) The main lighting switch, located at the upper right of the instrument panel (fig. 6), is in the OFF position when the handle is vertical. Turning the switch counterclockwise to its first position provides the blackout-marker lights (labeled “BO MK”). The second position, counterclockwise, provides the blackoutdriving light in addition (labeled “BO DR”), provided the blackoutdriving light is installed in place of the left headlight. Turning the switch clockwise from the OFF position provides first for the operation of the stop light only during daytime driving (labeled “STOP”). Turning it to the second position turns on the headlights (labeled “HD LTS”). In order to move the switch to these latter positions, it is necessary first to depress the lockout button at the top of the switch.
(2) Instrument panel lights are controlled by a lever-type switch handle at the upper left of the instrument panel (fig. 6). This switch regulates the intensity of illumination merely by turning the handle clockwise. There are two interior lights located in the hull roof; one above and forward of the assistant driver, and one in between the driver and assistant driver. Each light has two bulbs and two lenses, clear and red, which can be selected by means of the individual switch provided in each unit. Normally the red light is used; to turn on the white light, it is necessary first to release the stop.
/. Siren Switch. The siren switch is located on the lower hull front plate, and is operated by a button ahead of the driver’s left foot (fig. 7).
17
g. Accelerator. Individual foot accelerators are provided for the driver and the assistant driver. Each accelerator controls both engines. The accelerator on the assistant driver’s side should be disengaged when not in use. This disengagement is effected by releasing the spring-loaded plunger provided on the assistant driver’s side of the front throttle control relay (fig. 8). The hand throttle is on the driver’s side just above the instrument panel (fig. 7). It is self-locking in any position, and is released by means of a spring button in the center of the control knob.
h. Choke. An automatic choke mechanism is located on each carburetor to provide the correct fuel mixture for starting the engines. Fast idle with cold engines is obtained by using the hand throttle control.
i. Spark Control. The spark advance is provided by means of centrifugal weights in the distributor. It is fully automatic and is governed by engine speed. It requires no attention whatsoever from the driver.
HAND THROTTLE—, STEERING TRANSFER UNIT SHIFT FUEL TANK INSTRUMENT PANEL-A BRAKE LEVERS-, CONTROL LEVERy CONTROLS-? / \ s‘ V WIMiW—
k JAA'
T \
* ■ In X \
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SIREN SWITCH -J \ 1 - NEUTRAL PEDAL \ TRANSMISSION
DRIVER'S SEAT BAcA ACCELERATOR PEDAL^ SELECTOR LEVER
Figure 7. Driving controls.
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j. Steering and Braking Levers. (1) Dual steering and braking levers are mounted on cross shafts on the floor of the vehicle. One pair is provided for the driver, and another for the assistant driver. To steer the vehicle, pull the lever on the side toward which it is desired to turn. Either set of levers may be swung forward when not in use.
(2) Pulling back simultaneously on both steering levers slows down or stops the vehicle, depending on the effort applied. The stoplight lights whenever both levers are pulled back, provided the main lighting switch is in any position other than OFF. Parking brake controls are provided on the driver’s steering levers. These levers may be locked in the applied position by depressing the small knob in the center of each steering lever. Parking brakes are released by pulling back on the steering levers.
k. Shifting Controls. Two shifting controls are provided: a range-selector lever for the hydramatic transmissions, and a manual shifting lever for the transfer unit (fig. 9). The transmission-selector lever has three positions: NEUTRAL, DRIVE, and LOW. This control does not shift any gears, but simply positions the valves in the transmission-control mechanism. NEUTRAL prevents the units from transmitting the engine power; DRIVE permits shifting through all
ASSISTANT DRIVER'S ACCELERATOR PEDAL
ASSISTANT DRIVER'S
THROTTLE DISCONNECT
RAPD 33124
Figure 8. Disconnecting assistant driver’s accelerator.
19
four speeds; and LOW limits the transmission to first and second speeds in order to utilize the power of the engine through gear reduction for braking or low-speed operating on very rough terrain. The transfer unit shift lever has three positions besides NEUTRAL. Moving the lever to the right and rearward provides HIGH range; moving the lever to the right and forward provides LOW range; and moving the lever to the left and forward provides REVERSE (fig. 9).
I. Neutral Pedal. Although the hydramatic transmissions are automatic in operation, the transfer unit speed ranges are selected by manual shifting. In order to shift the transfer unit, it is necessary to have the hydramatic transmissions in NEUTRAL while the shift is being made. The transmissions can be shifted in NEUTRAL in one of two ways; either by moving the transmission-selector lever to NEUTRAL or by pressing the NEUTRAL pedal (fig. 7), which acts through the same linkage as the selector lever, but permits return to the selected lever position as soon as the pedal is released.
11 . Miscellaneous Operating Controls
a. Drivers’ Doors. The operation of each driver’s door is identical.
(1) To open, release both latches at front end of doors by turning latch handles approximately 90° (fig. 10). Pull down on driver’s
LOCKING PAWL KNOB TRANSFER UNIT SHIFT CONTROL LEVER
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/R. H. STEERING / Pip/|Nr dPA1zF , nrkr \_ TRANSMISSION
A BRAKE LEVER L PARKING BRAKE LOCK SELECTOR LEVER
Figure 9. Shift-lever quadrant.
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DOOR HINGE OPERATING LEVER _DOOR IN OPENED POSITION
\ xSs&- f fl
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^~\ /'^'*t
' ^^Bdoor hold open pin on hull
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DOOR LATCH HANDLES ADJUSTING LOCK SCREW
DOOR OPEN-EXTERIOR VIEW
DOOR HINGE
ASSEMBLY RETAINING SCREWS DOOR LATCH LEVERS
DOOR HINGE SAFETY CATCH HINGE ASSEMBLY DRIVERS DOOR OPERATING LEVER (CLOSED POSITION)
DOOR CLOSED-INTEROR VIEW
Figure 10. Drivers’ door controls.
21
door hinge-operating lever, release safety latch, and push up on the opposite side to raise door; then rotate lever to swing door to open position, again pull down on lever and push up on opposite side to lock in this position. The overcenter action of the hinge-operating lever keeps the door locked on the support. A safety latch has been provided to prevent the door-lock mechanism from accidentally releasing.
(2) To close drivers’ doors, pull down on door hinge operating lever, release safety latch, and push up on opposite side, which releases door from support. After swinging door to closed position, pull down on lever and push up on opposite side to lock in closed position. Turn the two latches at the front of the doors 90°.
b. Seat Adjustments. The seats for the driver and assistant driver have two adjustment ranges. First: 4-inch travel forward or backward in 1-inch variations is obtained by depressing the release lever on the left side of the seat (fig. 11) and sliding the seat forward or backward as desired. Second: There is a vertical range of 10 inches in 2-inch variations either up (to permit driving with doors open), or down (for driving when doors are closed). The lever for this adjustment is on the right side of each seat (fig. 11). To raise the seat, raise the control lever and take weight off seat. It will move upward and forward into position by spring action. To lower the seat, raise the control lever and body weight will force the seat down.
■ seat
T 5T ELEVATING ik /JP LEVER
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DRIVER'S
seat
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release lever ;
RAPD 331298
Figure 11. Drivers' seat adjustments.
22
c. Ventilator Controls. A two-way ventilator is located on the hull roof between the driver and assistant driver, and is operated by a four-position switch (fig. 12). To draw air into the driving compartment from the outside, the switch is turned to the left (to AIR-IN position) and to the FAST or SLOW position as desired. To take foul air out of the driving compartment, the switch is turned to the right (to AIR-OUT position) and to the FAST or SLOW position as desired. A circuit breaker reset button is located on the forward side of the unit and acts as a fuse in the circuit. A shut-off valve is provided in each air outlet elbow which will completely block the movement of air in or out of the vehicle at any time.
d. Ventilating Doors in Bulkhead. Additional ventilation for the driving compartment can be obtained by opening the ventilating doors in the bulkhead (fig. 13).
.12. Instruments
a. Ammeter. An ammeter for the entire electrical system is located in the lower center of the instrument panel (fig. 6), and is so connected to indicate the amount of charge or discharge in the main battery circuit.
DOME LIGHT AND
EMERGENCY
VENTILATOR
WINDSHIELD WIPER CIRCUIT IGNITION MOUNTING BREAKER RESET BUTTON . /—SWITCH SCREWS
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/—SWITCH BOX DOME u SWITCH \LSWITCH '—VENTILATOR
MOUNTING LIGHT \
SCREWS VENTILATOR CONDUIT RA PD 331242
Figure 12. Ventilator controls and emergency ignition switch.
23
BULKHEAD DOOR LATCHES
BULKHEAD DOOR
VENTILATOR SLIDING DOOR
DOOR LATCH
RADIATOR CORE
BULKHEAD
Figure 13. Bulkhead doors.
b. Engine Temperature Gages. Two gages for indicating engine temperatures are located in the upper left and right center of the instrument panel (fig. 6). These gages are connected electrically to the thermo units on the engines.
c. Oil Pressure Warning Signals. Warning signals for oil pressure (and engine water temperature) are located one on each side of the instrument panel (fig. 6). There is no oil pressure gage. A red signal lights if engine oil pressure drops below 12 pounds, or if engine water temperature increases above 240° F. There is also a warning signal for low transmission oil pressure. Do not drive vehicle if any of these signals light while the engines are running or the vehicle is in operation.
d. Speedometer. The speedometer, located in the upper center of the instrument panel, indicates the speed of the vehicle as well as the mileage traveled.
e. Tachometers. There are two tachometers, one for each engine, located to the left and right center of the instrument panel. These instruments are geared to the distributor drive shafts through flexible cables. They indicate the speed of each engine and the total revolutions each engine has been operated. Speed is indicated in hundreds, i. e., 10 indicates 1,000 revolutions per minute, and 25 indicates 2,500 revolutions per minute. Total revolutions are indicated in thousands.
24
Section VI. OPERATION UNDER ORDINARY CONDITIONS
13. Use of Instruments and Controls in Vehicular Operation
a. New Vehicle Run-in Test. Before a new or reconditioned vehicle is placed in service, be sure that the new vehicle run-in test described in paragraph 9 has been performed.
b. Before-operation Service. Perform the services in items (1) to (6) in paragraph 36 before attempting to start the engines. Start and warm up engines (par. 14) and complete the before-operation services.
Caution: Only gasoline with an octane rating of 80 or above can be used safely in this vehicle. Normally, the engines will not detonate (knock) ; if they do, it indicates either that the gasoline is of incorrect grade or that the ignition timing is incorrect. Check grade of fuel or readjust ignition timing (par. 73).
14. Starting Engines
a. Starting. Under normal conditions, the engines should be started as follows: Set brakes. Place transmission selector lever in NEUTRAL, and place transfer unit shift lever in the range in which the vehicle is to be driven. Turn fuel pump on for right or left tank. Turn on ignition switches for both engines, which will cause engine and transmission oil pressure signals to go on. (If the signals do not light, make sure emergency ignition switch is turned on.) Press starter buttons for both engines until engines fire.
Caution: It is important to turn electric gasoline pumps on before attempting to start engines, and equally important to turn them off when the engines are stopped. Do not allow pumps to operate on a dry tank.
b. Warm-up. After engines have started, pull hand throttle out to set idling speed at about 625 revolutions per minute, to prevent stalling during warm-up. Check to see that oil pressure warning signals go out. If these signals remain lighted, shut off engines and investigate cause. Check ammeter to see that generators are charging. Listen for unusual noises in power train or engines. The engines do not require any warm-up period in mild weather, except the time required to check the gages mentioned above. At temperatures below freezing, the warm-up periods given in paragraph 24 should be observed.
c. Flooding. If engines do not start readily in mild or warm weather, check for flooded condition. This can usually be corrected by depressing accelerator fully and holding it down while cranking engines. As soon as the engines start, close throttle to prevent “racing.” Flooding usually occurs more severely in one engine so that one engine starts and the other does not. In this case, shut off engine that is operating, press accelerator all the way down, and crank
25
flooded engine until it starts. The other engine can then be restarted with a minimum of “racing.” Flooding may be caused by dirt on needle valve, or by stuck choke shaft. The stuck choke shaft can be freed as shown in figure 94.
d. Starting One Engine with the Other. If only one engine starts readily, it can be used to start the other engine by placing the transfer unit shift lever and the transmission selector in NEUTRAL, running the other engine at about 2,000 revolutions per minute, and then moving transmission selector lever to DRIVE.
Caution: Inspect “dead” engine to be sure it turns over freely before attempting to start it by use of the other engine.
e. Cold Weather Starting. See paragraph 24 for detailed instruction on cold weather starting and warm-up.
1 5. Driving Vehicles
a. Driving Ranges. Normally, the vehicle is driven with the transmission selector lever in DRIVE and the transfer unit shift lever either in HIGH or in LOW range. Transfer unit HIGH range provides cruising gear ratios, and is to be used for traveling on roads or on relatively smooth, level terrain. Transfer unit LOW range provides power gear ratios, and is to be used for hill-climbing or for rough, sandy or muddy conditions.
b. Forward Driving.
Caution: Before driving vehicle make sure that gun is lowered and secure in travel lock, and that spade and gunner’s platform are raised and locked in closed position (par. 19Z> and c). To start vehicle, shift transfer unit into HIGH or LOW, as conditions warrant, move transmission lever to DRIVE, release parking brake controls and depress accelerator. Vehicle will start moving forward at a speed in proportion to the amount the accelerator is depressed. The vehicle will start out in first gear and the transmission will automatically shift into second, third, and fourth gears as the vehicle speed increases and engine load decreases. As vehicle loses speed, either because accelerator pedal is released or due to upgrade, the transmission will shift down automatically to a lower gear.
c. Steering. To steer vehicle, pull back on the right-hand steering lever to make right turn, or on the left-hand lever for a left turn. The lever that is being used should be applied firmly and then released fully, and this action repeated if necessary. The lever should not be held in a slightly applied position for long periods of time.
Caution: It is very important that the steering levers be held far enough forward to insure complete release of the bands at all times, except when steering or stopping; otherwise, brake lining wear will be excessive and oil will become overheated.
26
d. Reverse. To operate vehicle in reverse, first bring it to a complete stop if in motion; then depress the neutral pedal to put the transmissions in NEUTRAL, and move the transfer unit shift lever up to NEUTRAL, over to the left and forward into REVERSE. Release the neutral pedal. Four speeds automatically selected in the hydramatic transmissions are available in reverse.
Note. Depressing the neutral pedal puts both transmissions in neutral by means of the same linkage as the selector lever, but leaves the driver’s right hand free to shift the transfer unit. Releasing the pedal puts the transmission back in the range for which the selector lever is set. Neutral pedal should be used only when throttles are closed.
e. Rough Terrain. In negotiating rough or sandy terrain or heavy mud, not only should the transfer unit be shifted to LOW range, but the transmission selector lever should also be moved to LOW range to hold the transmission in second gear, and thus obtain the benefit of a steady pull. When the transmissions are in LOW range, they will up-shift only from first to second speeds, and will not go into third and fourth, thus permitting a steadier pull through very bad terrain, or providing more braking effect from engine compression when descending hills. Do not allow the engine speed to exceed 3,500 revolutions per minute for sustained periods.
Note. In negotiating long grades if transmission continually down-shifts and up-shifts back and forth, transfer unit must be shifted to high range to allow transmission to operate in its higher ranges.
f. Descending Hills. In descending moderately steep hills, the transfer unit should be shifted into LOW range before starting to descend. When descending long, very steep hills, the transmission selector lever should also be placed in LOW range before starting to descend, and brakes should be used to keep engine speeds below 3,500 revolutions per minute.
Caution: Transfer units shifts from HIGH to LOW must be made at speeds below 10 miles per hour. The NEUTRAL pedal must always be depressed when making the shifts.
16. Stopping Vehicle
To stop the vehicle, release the accelerator and pull back on both levers at the same time. There is no clutch to disengage. Both levers should be pulled back and engaged with heavy pressure, and then released fully. If the stop is to be made from relatively high speed, it is advisable to use heavy pressure intermittently rather than a continuous but lighter pressure.
Caution: Do not press down on neutral pedal when stopping, unless the transfer unit is to be shifted. Do not use neutral pedal as a clutch when starting.
27
17. Stopping Engines
To stop the engines, close the throttle until engines are idling at approximately 450 revolutions per minute. Run at this speed for 3 or 4 minutes and then turn off both ignition switches and shut off the fuel pump switch. If engines are extremely hot, run at 2,000 revolutions per minute for a few minutes to cool down before reducing speed to normal idle. Finally, open master battery switch.
Caution: Always turn off ignition switches before opening master battery switches. Never operate engines with master switch off.
18. Towing Vehicle
a. Towing to Start Vehicle. The engines can be started in an emergency by towing the vehicle, provided the following procedure is observed after checking to make sure the engines turn freely:
(1) Release brakes.
(2) Place transmission selector lever in NEUTRAL and transfer unit shift lever in LOW.
(3) When speed reaches approximately 4 miles per hour, turn on both ignition switches and one fuel pump switch, and move transmission selector lever to DRIVE.
(4) Continue towing until engines fire.
b. Towing a Disabled Vehicle. When towing a vehicle, several precautions must be taken:
(1) Tow the vehicle with the transfer unit in NEUTRAL, if possible. If transfer unit is damaged or disabled, disconnect the propeller shaft at the controlled differential pinion shaft yoke.
(2) If controlled differential is disabled, disconnect the two short propeller shafts at the final drive yokes.
(3) If final drive units are disabled, break tracks and two vehicle on track suspension wheels.
Caution: Tow bar must be used under these circumstances.
c. Towing Procedures. In towing a vehicle, changes in direction must be made by a series of slight turns so that the vehicle being towed is, as nearly as possible, directly behind the one doing the towing. This prevents the cable from contacting the track which might damage both the cable and track blocks. If no operator is available to steer the disabled vehicle, or if it is being towed with the tracks removed, the cable should be attached by the “short hitch” in which it is threaded through both eyes on the vehicle to be towed, and then crossed and passed through both shackles of the towed vehicle.
Caution: Tow bar must be used when towing vehicle with tracks removed.
28
Section VII. HOWITZER MOUNT CONTROLS AND OPERATION
19. Controls
a. General. The howitzer mount is located at rear of vehicle and is assembled on a continuous bearing. The mount may be traversed 17° to left or 21° to the right by means of a hand crank. The mount has two travel locks consisting of a traverse and a howitzer lock. Both travel locks (fig. 16) should be used wThen the vehicle is being driven over the terrain. The howitzer can be elevated 45° or depressed 5° from the horizontal position by means of a hand crank or an electrical mechanism. The rear of the vehicle is fitted with a spade and gunner’s platform which serves as a tailgate when in the RAISED position and as an anchor and platform when in the LOWERED position (figs. 14 and 15).
b. Winch Crank (fig. 14). The winch is operated from either end of the crankshaft by one or both of the cranks provided. When operat-
SPADE WINCH CRANK WINCH BRAKE LEVER
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TOOLS PLATFORM TRAVEL LOCK TRAVEL LOCK
Figure 14- Spade and gunner’s platform.
752022 0—47------3
29
ing the winch from the gunner’s compartment, the crank is turned counterclockwise to raise the platform and spade assembly, and clockwise to lower the assembly. When operating the winch from the side of the vehicle the crank is turned clockwise to raise the spade and platform assembly, and counterclockwise to lower the assembly.
c. Winch Brake Lever (fig. 14). The winch brake lever is located on the right side of the winch frame. The lever is moved toward the rear of the vehicle to apply the brake.
d. Winch Locking Pawl. The locking pawl is located on the front right side of the winch frame. The pawl is hand-released when tension is on the cable, by turning the crank in the gunner’s compartment counterclockwise. The locking pawl when engaged with the drum gear provides a safety lock while raising the platform and spade assembly.
e. Spade Travel Lock (fig. 14). The two spade travel locks are toggle latches, bracket-mounted on the rear of the vehicle. The latches engage studs on the spade when the spade assembly is in the raised position. The travel locks are swung upward to release and downward to lock the spade assembly.
/. Platform Lock (fig. 14). The two platform locks are pivotmounted on the arms of the spade. The locks are used to hold the platform in the closed position when the spade is raised.
g. Howitzer Travel Lock (fig. 16). The gun travel lock is mounted on the hull roof above the driver’s compartment. The lock is used to hold the weapon tube in traveling position. The lock is secured by swinging up to a vertical position, clamping upper half of lock around tube and tightening clamp nut. The lock is released by loosening clamp nut at top of clamp, tilting nut away from gun tube, and lifting upper half of lock away from weapon tube.
h. Traverse Lock (fig. 16). Two traverse locks consisting of lock clamps and lock nuts and are mounted on the rear of the weapon base. The locks are used to secure the howitzer and take the play out of the traversing mechanism. The locks are released by inserting end of utility bar in hole in clamp nut, loosening nut until lock clamp can be freed from weapon mount base. The locks are secured by placing the lock clamps in position at rear of weapon base and tightening clamp nuts.
i. Traversing Handwheel (fig. 17). The traversing handwheel is located at the rear left side of the howitzer. It is used to traverse the howutzer after disengaging travel lock, traversing locks, and elevating howitzer slightly to clear travel lock.
j. Hand-Operating Elevation Wheel (fig. 17). The hand-operating elevation wheel is located at the rear left of the howitzer. It is used to raise or lower the howitzer manually. Before using the handoperating elevation wheel, the control lever in the elevation mechanism
30
control box must be moved to the MANUAL position and the travel lock disengaged.
k. Elevation Mechanism Control Box (fig. 17). The elevation mechanism control box is located at the rear left of the howitzer. The box contains the control handle for manual or electrical elevation of the howitzer. Moving the control handle to the MANUAL position permits use of hand-operating elevation wheel. Moving the control lever to the left from MANUAL position to either UP or DOWN position, elevates or depresses the gun electrically. The master battery switch must be closed for electrical operation and the gun travel lock must be disengaged before either manual or electrical elevation.
I. Limit Control Switch (fig. 17). The limit control switch is located at the rear left of the howitzer. The switch is synchronized to the howitzer and prevents overrun when electrically elevating or depressing the howitzer.
20. Operation
a. Spade and Gunner’s Platform. Before firing the howitzer it is necessary to lower the spade and gunner’s platform. The spade acts as an anchor by preventing the vehicle from moving back on the weapon recoil and the platform serves as a loading table on which the gunner stands. To lower the spade and platform, place winch crank on winch crankshaft, release winch locking pawl and tighten cable enough to release spade travel locks (fig. 14). After spade travel locks (left and right) have been released, firmly grasp winch brake handle and apply brake by pulling handle to the rear. Holding brake in applied position, remove winch cranks (both cranks) and gradually release winch brake.
Caution: Operator must stand to right side of spade and platform in case spade should accidentally drop faster than winch brake will control.
Lower spade about 6 inches and push platform toward closed position. Platform travel locks (both sides) will automatically swing to released position. Gradually release pressure on winch hand brake lever and allow spade and platform to lower to ground. Back vehicle so that spade buries itself well into ground and so that gunner’s platform is slightly slanting toward rear (fig. 15). The vehicle is now anchored and howitzer may be prepared for action. To raise spade, drive the vehicle forward until spade is level with ground. Place both winch hand cranks on winch shaft and turn cranks to wind cable on winch drum. After spade is clear of ground, brush off excessive dirt, mud, etc. Raise spade and platform by turning winch cranks until spade is about 6 inches from closed position. Push platform toward closed position and throw both platform travel locks over to locked position. Continue to crank winch until spade is in the closed position
31
Figure 15. Spade buried into ground.
and until both spade travel locks will engage with stud on spade (fig. 14). Pull down on travel lock handle and lock spade. See that winch locking pawl is engaged in winch gear and remove both winch cranks.
b. Travel Locks. Before firing howitzer, both traverse and howitzer travel locks must be released. To release howitzer travel lock, loosen clamp nut at top of clamp, tilt nut away from weapon tube and lift clamp band away from barrel (fig. 16). To release traverse locks, insert end of utility bar in hole in clamp nut and loosen nut (fig. 16). Lower traverse lock clamp free of weapon mount base. After use, turn howitzer to straight-ahead position and depress howitzer to lower cradle of howitzer travel lock. Position upper clamp band over weapon tube and tighten clamp nut. Place traverse lock clamps (left and right) in position at rear of weapon base and tighten clamp nuts securely.
c. Manual Elevating. Disengage howitzer travel lock at front of howitzer barrel. Open elevation mechanism control box on left side of howitzer (fig. 17) and move control lever to MANUAL position. To raise or lower howitzer, turn hand wheel at rear of elevating gear box (fig. 17).
d. Traversing. Disengage traversing and howitzer travel locks. Elevate howitzer slightly to clear elevation travel lock. To traverse
32
GUNNER’S _Z '-SPADE
PLATFORM
33
TRAVERSING LOCK
CLAMP NUT-i /—CLAMP CARRIAGE (REAR) CLAMP NUTS
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) Prior to attempting a start, see that everything is in readiness so that the engine will start on the first trial. Try to avoid having the engines fire a few times and then stop. Water is one of the products of gasoline combustion, and in a cold engine this water may form a frost and make it impossible to start without heating the engine to above 32° F.
(c) Start one engine at a time, with the accelerator and hand throttle fully closed. This will set the automatic choke correctly. No further choking is possible or necessary. Start one engine with another (par. 14) if battery capacity is low.
Caution: Do not pump or depress the throttle pedal swiftly to the floor before starting the engine. This will force raw gasoline into the cylinders, causing flooding, decrease oil film in the cylinders and hinder starting.
(zZ) After the engines have started, set the hand throttle to allow them to run at 800 to 900 revolutions per minute for 4 to 5 minutes, to allow the oil to warm up before opening the throttle further. This should be done with the transmission selector lever in neutral. Then shift the selector lever to DRIVE and allow the engine to idle for several minutes more to warm up the oil in the transmission. Do not drive the vehicle over 5 miles per hour for at least 10 minutes after starting, to permit the oil in the transfer unit and controlled differential to warm up.
(2) Temperature below 30° F. («) Cover engines with tarpaulin, tent, or portable shed. Place oil stoves, firepots, or four to five ordinary kerosene lanterns under the covering about 3 hours prior to the time the start is to be made.
40
(Z>) Keep the vehicle in sheltered areas, especially areas sheltered from wind. Cold winds increase starting difficulties.
(c) If the vehicle is equipped with a winterization kit, keep the heater operating and the covers closed whenever the engines are not operating.
Z>. Stopping Engines. Increase engine speed just before turning off ignition; then turn off ignition switches, releasing accelerator at the same time. As the engine coasts to a stop, it will blow out all the residual products of combustion and leave only air and gasoline vapors in the engine.
c. Inspection. Inspect the vehicle frequently. Shock resistance of metals, or resistance against breaking, is greatly reduced at extremely low temperatures. Operation of vehicles on hard, frozen ground causes strain and jolting which will result in screws breaking or nuts jarring loose.
25. Operation Under Dusty Conditions
a. General. When opeiating under dusty or sandy conditions, special precautions must be taken to prevent excessive wear and damage to the moving parts of the power unit and suspension system.
b. Air Cleaners and Breathers. Under extremely dusty conditions, the air-cleaner oil reservoirs must be cleaned every 2 to 4 hours, or more frequently as required. Air-cleaner elemenst must be cleaned when inspection reveals that any appreciable quantity of dirt has accumulated to restrict the free flow of air or their capacity to trap the dust has been reached. Continued operation of the engine with dirty or saturated air cleaners will cause damage to the engine which will continue and increase long after the air cleaners have been cleaned. The final drive breathers must be cleaned more frequently as required when operating under dusty conditions to prevent premature wear and damage to these units. The engine oil filter will be cleaned more frequently as required to maintain its efficiency. Carefully examine all lubricating oil bayonet gages for evidence of gritty substance that would indicate the oil has become contaminated and must be changed.
c. Cooling System. Inspect radiators and oil coolers frequently to make sure air passages are not restricted by accumulation of dirt. Clean the radiator cores by flushing with water under pressure or blow out with compressed air.
d. Care of Track Suspension System Under Dusty Conditions. Lubricate track-suspension system more frequently to cleanse the bearings of any sand or dirt that may have worked into the hubs or housings. Inspect track-suspension system units including track links for evidence of premature wear. Remove worn units promptly and install new ones to prevent ultimate failure.
41
26. Submersion
a. General. If a vehicle has been submerged in water, particularly salt water, the problem of arresting rust and corrosion calls for immediate action, if the tactical situation permits.
b. Stopping Rust and Corrosion After Submersion. Remove water from every part of the vehicle and dry all exposed parts with cloths and compressed air. If the suspension system has been submerged for even a few minutes, lubricate all suspension points to cleanse the bearings of water and grit. Coat all parts accessible, inside and out, with preservative lubricating oil. If preservative compounds are not available immediately, use ordinary engine oil temporarily until preservative compounds can be obtained. In an emergency, leave vehicle submerged to keep air from wet metal parts until preservative compounds can be secured. In the case of assemblies which have to be disassembled and dried, perform these operations as soon as the tactical situation permits.
c. Permanent Protection. Regardless of the temporary steps taken as outlined in subparagraph b above, the vehicle must be delivered at the earliest possible moment to higher echelons for disassembly, cleaning, repair, and permanent protection. The higher echelons must pay particular attention to possible damage caused by the sudden cooling of parts of the engine or transmission which were at operating temperatures at the time of submersion. If submerged in salt water for any length of time, aluminum or magnesium parts will probably be unfit for further use and must be replaced.
Section X. DEMOLITION TO PREVENT ENEMY USE
27. General
a. Destruction of the vehicle, when subject to capture or abandonment in the combat zone, will be undertaken by the using arm only when, in the judgment of the military commander concerned, such action is necessary.
b. The instructions which follow are for information only. Certain of the methods of destruction outlined require TNT and incendiary grenades which may not be normal items of issue. The issue of these materials, and the conditions under which destruction will be effected, are command decisions in each case, according to the tactical situation.
c. If destruction is resorted to, the vehicle must be so badly damaged that it cannot be restored to a usable condition in the combat zone either by repair or cannibalization. Adequate destruction requires that all parts essential to the operation of the vehicle be destroyed or damaged beyond repair. Equally important, the same essential parts must be destroyed on all like vehicles so that the enemy cannot construct one complete operating unit from several partially damaged ones.
42
28. Detailed Instructions
a. Destruction of Sighting and Fire-Control Equipment. All fire-control equipment, including optical sights and binoculars, is difficult to replace. It should be the last equipment to be destroyed, if there is any chance of personnel being able to evacuate. If evacuation of personnel is made, all possible items of fire-control equipment must be destroyed. Thoroughly burn firing tables, trajectory charts, slide rules, and similar items. Thoroughly smash all optical equipment.
b. Destruction of 155-mm Howitzer. (1) Methods. Four methods of destroying the howitzer are outlined below in their order of effectiveness. These instructions apply to the howitzer only. To effect demolition of the entire howitzer motor carriage, destruction as outlined in this subparagraph must be accomplished in conjunction with destruction of the vehicle itself (subpar, c below) and the sighting and fire-control equipment (subpar, a. above).
(2 ) Method No. 1. (a) Open drain plug on recoil mechanism, allowing recoil fluid to drain. It is not necessary to wait for the recoil fluid to drain completely before firing the cannon in step (<7) below.
Caution: Firing the cannon with drained recoil mechanism without proceeding with steps (5) and (e) below is not a satisfactory method of destruction.
(5 ) Place an armed (safety pin removed) antitank grenade M9A1, HE, or armed (safety pin removed) antitank rocket M6 in the tube with the nose end toward the rear. The grenade or rocket must be centered in the tube, using a wooden adapter. An alternate for the wooden adapter is the use of waste.
() Ram an HE shell (without base fuze) into the forcing cone and place TNT blocks behind it, as specified above. Close the breechblock and detonate the TNT charge. A sufficient length of safety fuse
43
should be used to permit personnel to reach safety zone or cover. The fuse may be routed through the primer hole in the spindle.
(c) Attention is invited to the fact that, for the larger calibers, the number of blocks to be used is an estimate not proved by tests.
(4) Method No. 3. (a) Place unfuzed incendiary grenades M14 on their sides, one on top of another, in the chamber. Close the breech. Equip another incendiary grenade with a 15-second safety fuse, ignite, and toss it in the muzzle. Quickly elevate the cannon to its maximum elevation. Elapsed time: 3 to 5 minutes. Six to eight grenades per cannon are required.
(Z>) The metal from the grenades will fuse with the interior of the breechblock, making it impossible to open the breech.
(5) Method No. 4- («) Eire adjacent cannons at each other at point-blank range, using HE or AP shells. Two or more direct hits from a weapon of the same caliber, on a vital spot such as the breech mechanism, recoil mechanism, or tube, should adequately destroy the artillery piece. Fire from cover. Danger space is from 200 to 250 yards.
(6) Destroy the last weapon and carriage by the best means available.
(c) Danger from cannibalization is inherent in this method.
(6) Ammunition. Instructions for demolition of ammunition are contained in TM 9-1901.
c. Destruction of Vehicle. Three methods of destroying the vehicle are outlined below in their order of effectiveness. These instructions apply to the vehicle only. To effect demolition of the entire howitzer motor carriage, destruction as outlined in this subparagraph must be accomplished in conjunction with destruction of the cannons, and sighting and fire-control equipment (a and b above).
(1) Method No. 1—by explosives, (a) Remove and empty portable fire extinguishers. Puncture the fuel tanks.
(6) Prepare a 3-pound and a 2-pound TNT charge, with tetryl nonelectric caps and about 6 feet of safety fuse in each charge. Open the engine compartment and place the 3-pound charge between the engines. Place the 2-pound charge against left side of the transfer unit, as near differential as possible. Place a i/2-pound charge of TNT against left fuel tank. Use only a cap (no fuse) in this charge. Point the cap end toward the 3-pound charge.
Caution: If charges are prepared beforehand and carried in the vehicle, keep the caps and fuses separated from the TNT charges until they are to be used.
(t?) If sufficient time and materials are available, prepare and place a 2-pound TNT charge at the center of each track assembly.
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Identifying No. o Cd C5 o c 1O d i 41-A-18-245, B7079311 41-B-1586-300, A266327, KM- J-1636-SA-5. 17-C-568, B257839 41-F-2997-86, D78191 41-G-12, A344920, KM-S-1460-A. 41-G-446, B298875, KM-S-1467- M6. 41-H-1397, A380406, TEC-4-223. 41-L-1400, A7079701 41-L-1425, B226787 41-P-596-300, B7080501 41-P—2907-196. A7079316 41-P-2957-33, C73615 41-R-2373-120, B7080557 41-R-2383-950, B296108, BMD- T-70-103. 41-R-2390-450, B296095, BMD- T-70-121. 41-R-2396-375, B7080461
Item ADAPTER, bearing race remover ADAPTER, puller, slide hammer, torsion bar and compensating link pin replacer. BOLT, eye, transmission lifting CABLE, extension rubber covered with female plugs at both ends, double conductor, stranded No. 1 AWG 20 feet long. FIXTURE, track connecting and connector pulling. GAGE, adjusting, rear, servo (used in transmissions 1-M-H-19875 and up). GAGE, transmission, oil pressure HANDLE, for removers and replacers (length over-all 8% inches). LIFTER, track wheel, right and left, in set.. LIFTER, valve, remover and replacer PIN, drift, black pin PULLER, end, shock absorber PULLER, slide hammer type, bogie gud- geon. REMOVER, roller, outer bearing race track support. REPLACER, bearing and seal, track and compensating wheel. REPLACER, grease retainer REPLACER, retainer, grease (track support roller).
47
References
Item Identifying No. ----------------- Use
Fig. Par.
REPLACER, seal, track support roller- 41—R—2397—875, A380369, BMD- 144 151 Suspension component replace-
T-70-102. ment.
SCREW, remover, bearing, threaded, 1% 41-S-1047-200, A7079203_______________ Use with 41-R-2373-120.
inch 12NF-2, length overall 8%
inches.
SLING, engine, lifting---------- 41-S-3831-300, C7079282--- 67 67, 68 Engine replacement.
SLING, final drive, lifting----- 41-S-3832-35, C7079301---- 126 141, 142 Final drive replacement.
48
Section XIII. LUBRICATION
32. Lubrication Order
a. War Department Lubrication Order LO 9-744 prescribes organizational lubrication maintenance for this vehicle. This lubrication order is issued with each item of materiel and is to be carried with it at all times. In the event the materiel is received without a copy, the using arm shall immediately requisition a replacement in conformance with instructions and lists in FM 21-6. Lubrication to be performed by Ordnance maintenance personnel is covered in paragraph 33.
b. Instructions on the lubrication order are binding on all echelons of maintenance, and there shall be no deviations.
c. Service intervals specified on the lubrication order are for normal operation of 500 miles a month. Reduce to compensate for abnormal operation and extreme conditions, such as excessively high or low temperatures, prolonged periods of high-speed operation, continued
ENGINE THROTTLE CARBURETOR AIR CRANKCASE VENTILATOR OIL FILLER CROSS SHAFT INTAKE ELBOW AIR CLEANER
i I i
i / 1 '■ '"’x A
\ < ’wfvZ fyP-
©zff'- TO r Z«LS
TRANSMISSION CRANKCASE VENTILATOR HOWITZER TRAVERSING
OIL FILLER AIR CLEANER GEAR BOX RA „„
Figure 21. Engine compartment, showing fillers.
49
operation in sand or dust, immersion in water, or exposure to moisture, any one of which may tend to impair the functioning of the materiel. Intervals may be extended during inactive periods.
d. Lubricants are prescribed in the “Key” in accordance with three temperature ranges, about +32° F., +32° to 0° F., 0° to —40° F., and below —40° F. When to change grades of lubricants is determined by maintaining close check on operation of the materiel during the approach to change-over periods, especially during initial action. Sluggish starting is an indication of lubricants thickening, and is the signal to change to grades prescribed for the next lower temperature range. Ordinarily, it will be necessary to change grades of lubricants only when air temperatures are consistently in the next higher or lower range.
A. Distributor Grease Cup
B. Distributor Cam Wick
C. Water Pump Fitting
D. Fan Shaft Universal Joints
Figure 22. Lubrication points on engine.
50
A. Final Drive Filler
B. Controlled Differential Filler
C. Transfer Unit Filler
D. Transfer Unit Shift Lever
E. Steering Brake Lever Shafts
Figure 23. Lubrication points in driving compartment.
51
s p DIFFERENTIAL DRAIN COVER ENGINE (2)
/ r TRANSFER UNIT DRAIN COVER
/ HULL FLOOR DRAIN VALVES (9)
IlPfefc-.-__— —< — ———<’■'
o VFW>
■ ' I ®—L
I l . J- ' - ——1 F“1
v • A i
[ I [o x O ' ' .
f© © © Lr.,^ \_
--0©=^^^
TRANSMISSION_\ ^^TORSION BAR ANCHOR COVERS (10)
FINAL DRIVE DRAIN COVER (2) CENTER HULL FLOOR COVER (2)
DRAIN COVERS GASOLINE TANK DRAIN COVER (2) RA PD 331937
Figure 24 Drain openings in hull.
33. Detailed Lubrication Instructions
a. Lubrication Equipment. Each piece of materiel is supplied with lubrication equipment adequate to maintain the materiel. This equipment will be cleaned both before and after use. Lubrication guns will be operated carefully, and in such a manner as to insure a proper distribution of the lubricant.
FLYWHEEL COVER
FLYWHEEL COVER
OIL PAN
OIL COOLER COVER
Figure 25.
WATER DRAIN PLUG
RA PD 331353
Transmission drains.
DRIVEN TO£US
53
OIL DRAIN \ PLUG *
A. TRACK SUPPORT ROLLER
C. TRACK WHEEL
E. GUNNER’S PLATFORM HINGE PIN
B. TORSION ARM BEARING
F. PLATFORM AND SPADE WINCH
Figure 26. Lubrication points on track suspension and gunner’s platform.
54
D. COMPENSATING WHEEL LINKAGE
b. Points of Application. (1) Lubrication fittings, grease cups, oilers, and oilholes are readily located by reference to the lubrication order. Wipe these devices and the surrounding surfaces clean before lubricant is applied.
(2) Where relief valves are provided, apply new lubricant until the old lubricant is forced from the vent.
c. Cleaning. Dry-cleaning solvent or Diesel fuel oil will be used to clean or wash all parts. Use of gasoline for this purpose is prohibited. After washing, parts will be thoroughly dried before applying lubricant. Rifle-bore cleaner may be used for armament parts.
b. Lubrication after Disassembly by Higher Echelon. (1) Universal joints. Every 6 months, remove and disassemble universal joints on final drive, propeller shaft, and fan drives. Clean bearings in dry-cleaning solvent, dry thoroughly, and repack with general-purpose grease (No. 1) for above +32° F., or general-purpose grease (No. 0) for below +32° F.
(2) Starters. Every 6 months, disassemble and repack bearings with high-temperature grease (special).
(3) Cradle trunnion bearings and elevating shaft bearings. Every 6 months, disassemble, clean, and lubricate with lubricating grease (special).
(4) Variable recoil gears. VuNwrg 6 months, remove gear housing cover, clean, and lubricate with general-purpose grease.
UNIVERSAL JOINTS
TRAVERSING GEAR SHAFT BUSHING
Figure 27. Lubrication points at rear of howitzer (left side).
55
BREECHBLOCK BREECHBLOCK RECUPERATOR AND CRADLE
HINGE PI Nd V CRANKSHAFT JOURNAL F COUNTER-RECOIL A LINER
\ /wVTiii
P ’>' \ ■ \ VrA PD 331964
BREECHBLOCK \ SAFETY \ CARRIAGE BELLEVILLE
ROTATING CAM\ LATCH \ SUPPORT LINER SPRING
FIRING MECHANISM BREECH OPERATING HANDLE LATCH
Figure 28. Lubrication points at rear of howitzer (right side).
(5) Traversing handwheel gear case. Every 6 months, disassemble and wash gears and case with dry-cleaning solvent. Coat gears with OD grease and reassemble.
(6) Traversing worm gear case. Every 6 months, disassemble and wash all parts in dry-cleaning solvent. Reassemble and fill case to prescribed level with engine oil.
(7) E quilibrator end bearings. Every 6 months, or at time of disassembly for repair or overhaul, clean and repack bearings with OD grease.
(8) Carriage support liner. Every 6 months, disassemble and wash all parts in dry-cleaning solvent. Repack liner with OD grease and reassemble.
(9) Elevating bevel gear case. Every 6 months, or when disassembled for repair or overhaul, clean and repack upper v;orm gear bearing and coat bevel gears with OD grease.
(10) Elevating shaft bearings. Every 6 months, disassemble, clean, and repack bearings with OD grease.
56
J (
^^^RECOIL SIDE -J J
CRADLE L!NERJf— VfTX /“EXPOSED RECOILS1JDEM
>T
Zy~5' ' VARIABLE RECOIL «
••• iinbL V ' " H * 1
.^»X^M|end bearin
R A PD331918A-
Figure 29. Lubrication points at front of howitzer (right side).
।
/I /
Jl
Il : E Q U (L: B PA TO HE
1 ■ — J l^r-Hff *** lbNP BEARINGMjyffi ■•
JMiMMIlMaH^APP„3319j8_Bj
Figure 30. Lubrication points at front of howitzer (left side).
57
Bj^^^^FILL and LEVEL .
» * jnl fc*- • V ’•’*«?
W IfcS \ ^P8
IIpW \
/ fe JCnt'
'K.; '■■ is^-- ■ ■
F*^ |T* |j~ J>1| w
1 ■ -J^—
DRAIN —rd 331919A
Figure 81. Lubrication points on elevating mechanism.
(^EQUILIBRATOR SPRINGS, FM 1' / ./ f
poD---r ;''c
Z RECOIl CYLINDER
REPLENISHER j ''
RECOIL
REPLENISHER LEVEL \ Jc_r RA PD 331919B^^^^Bb|
Figure 32. Lubrication points on recoil mechanism.
58
\ -A DRIVE SHAFT UNIVERSAL JOINT -y
TRAVERSING PINION BEARING\ \ \ ggC b j 1 I-—-
\\k J M/a
^TRAVERSING WORM GEAR CASE FILL IsL
TRAVERSING^AK^^PI^m^^^lh^,...^
j^O / v 1 ■
«>WAM 1
331920A^
Figure 33. Lubrication points on traversing mechanism.
DRIVE SHAFT UNIVERSAL JOINT —\ I ।
e i KU
ELEVATING ARC and PINION '. MM e B b'i
. RA PD 33192OBT
■-< kw«»! i •
Figure 3j. Lubrication points of elevating arc and pinion-pintle bearing.
e. Reports and Records. (1) Report unsatisfactory performance of materiel to the Ordnance Office responsible for maintenance, in accordance with TM 38-250.
(2) A record of lubrication for the carriage may be maintained in the Preventive Maintenance Roster (WD AGO Form 460). A record is kept in the artillery gun book.
59
60
Figure 36. Lubrication points on howitzer travel lock.
TRAVERSING JX '''C .
H3B GEAR SHAFT Y
% UNIVERSAL JOINT ' Wl
*5SSKz"\^' J
iS X /
CARRIAGE. -JI 1
SUPPORT LINER ELEVATINGW //
ilx /577mGEAR case® /?.
drain< fill ond leJ£ ^carriage support LINER
GUN CARRIAGE (LEFT SIDE) GUN CARRIAGE (RIGHT SIDE)
fi- SKJI 1
vSCRADLE LINER fiy
GUN CARRIAGE (FRONT) CRADLE LINER
(LOWER REAR VIEW)
Figure 35. Lubrication points on howitzer and carriage.
^RA PD 331922
Section XIV. PREVENTIVE MAINTENANCE SERVICES
34. General Information
a. Responsibility and Interval. Preventive maintenance services as prescribed by AR 850-15 are a function of using organization maintenance personnel, and their performance is the responsibility of the commanders of such organizations. These services consist generally of Before-operation, During-operation, At-halt, After-operation, and Weekly Services performed by the crew, and the scheduled services to be performed at designated intervals by battery maintenance personnel.
b. Definition of Terms. The general inspection of each item applies also to any supporting member or connection, and is generally a check to see whether or not the item is in good condition, correctly assembled, secure, or excessively worn.
(1) The inspection for “good condition” is usually an external visual inspection to determine whether the unit is damaged beyond safe or serviceable limits. The term “good condition” is explained further by the following: not bent or twisted, not chafed or burned, not broken or cracked, not bare or frayed, not dented or collapsed, not torn or cut, not deteriorated.
(2) The inspection of a unit to see that it is “correctly assembled” is usually an external visual inspection to see whether it is in its normal assembled position in the vehicle.
(3) The inspection of a unit to determine if it is “secure” is usually an external visual examination; a wrench, hand-feel, or a pry-bar check for looseness. Such an inspection must include any brackets, lock washers, lock nuts, locking wires, or cotter pins used in assembly.
(4) “Excessively worn” will be understood to mean worn beyond serviceable limits, or to a point likely to result in failure if the unit is not replaced before the next scheduled inspection.
35. Crew Maintenance
a. Purpose. To insure mechanical efficiency, it is necessary that the vehicle be systematically inspected at intervals each day it is operated and weekly so defects may be discovered and corrected before they result in serious damage or failure. Certain scheduled maintenance services will be performed at these designated intervals. Any defects or unsatisfactory operating characteristics beyond the scope of first echelon to correct must be reported at the earliest opportunity to the designated individual in authority. The services set forth in paragraphs 36, 37, 38, and 39, are those performed by the crew Beforeoperation, During-operation, At-halt, and After-operation and Weekly.
b. Use of War Department Form 48. Driver preventive maintenance services are listed on the back of War Department Form 48
752022 0—47——5
61
(Driver’s Trip Ticket and Preventive Maintenance Service Record) to cover vehicles of all types and models. Items peculiar to this vehicle but not listed on Form 48, are covered in manual procedures under the items with which they are related. Certain items listed on the form that do not pertain to this vehicle are eliminated from the procedures as written into the manual. Every organization must thoroughly train each driver in performing the maintenance procedures set forth in this manual, whether, or not they are listed specifically on Form 48. The items listed on Form 48 that apply to this vehicle are expanded in this manual to provide specific procedures for accomplishment of the inspections and services. The services are arranged to facilitate inspection and conserve the time of the driver, and are not necessarily in the same numerical order as shown on Form 48. The item numbers, however, are identical with those shown on that form.
36. Before-Operation Service
a. Purpose. This inspection schedule is designed primarily as a check to see that the vehicle has not been damaged, tampered with, or sabotaged since the After-operation Service was performed. Various combat conditions may have rendered the vehicle unsafe for operation and it is the duty of the driver to determine whether or not the vehicle is in condition to carry out any mission to which it may be assigned. This operation will not be entirely ommitted, even in extreme tactical situations.
b. Procedures. Before-operation Service consists of inspecting items listed below according to the procedure described, and correcting or reporting any deficiencies. Upon completion of the service, results should be reported promptly to the designated individual in authority.
(1) Item 1, T amp ering and damage. Look over vehicle, equipment, and armament for damage which may have occurred from falling debris, shellfire, sabotage, or collision since parking vehicle. Open engine compartment and look for signs of tampering or sabotage, such as loosened or damaged accessories, loose fuel or oil lines, or disconnected throttle linkage.
(2) Item 2, Fire extinguishers. Examine cylinder of fixed system for tight mountings and closed valves. See that wire seal is intact. Look into engine compartment to examine extinguisher lines and nozzles for good condition and correct aiming. Be sure nozzles are not clogged. Inspect portable extinguishers for good condition and security. Make sure that wire seals are intact.
(3) Item 3, Fuel, oil, and water. Check amount of fuel in each fuel tank and add where required. Check oil level in each engine. Add as much oil as necessary bring level to FULL mark. Check level of
62
coolant in each radiator and add water if necessary. In freezing weather, be sure to add antifreeze compound of proper strength when considerable water must be added.
Caution: Do not fill fuel tanks or radiators to overflowing. Leave room for expansion.
(4) Item, 4, Accessories and drives. Examine security of mountings of all accessible accessories and of generator and fan drive belts on each engine. See that fan and generator belts have %- to %-inch, fingerpressure deflection.
(5) Item 6, Leaks, general. Look under vehicle for any indications of fuel, oil, or water leaks. Inspect engine compartment for evidence of leaks, particularly at engine oil pan, and at fuel and oil lines. Trace all leaks to their sources and correct or report them to proper authority. Close engine compartment.
(6) Item!\ Engine warm-up. Start engines (par. 14). Observe if choke action is satisfactory. Note action of starter mechanism, particularly whether starter has adequate cranking speed. If low-oil-pressure warning light does not go out, engine should be stopped and trouble corrected or reported to designated authority. Inspect hand throttle for free operation; return it to idling position and let engine idle while proceeding with the following Before-operation Service.
(7) Item 9, Instruments, (a) Warning signals. The warning signals for engines and transmissions should go on when ignition switches are turned on, and should go out as soon as engines are started.
(Z>) T achometers. Observe both tachometers to see that they indicate approximate engine revolutions per minute, and that they register accumulating revolutions.
(c) Engine temperature gages. Observe engine temperature gages to determine whether or not they are functioning. Engine temperature should increase gradually to operating range of 160° to 210° F. Maximum safe operating temperature is 240° F.
(, Tracks. Examine tracks and wheel tires to see that they are secure, not damaged, and that track tension is satisfactory (par. 144). Remove stones and trash from tracks and suspension system.
(6) Item 16, Leaks—General. Look around and under vehicle and in engine compartment for indications of fuel, oil, or coolant leaks.
(7) Item Jfi, Air cleaners. If operating under extremely dusty or sandy conditions, inspect air cleaners at each halt, to see that they are in condition to deliver clean air properly. Service as required.
(8) Item T9, Fenders. Examine fenders and sand shields to see that they are secure and in good condition.
(9) Item 50, Towing connections. Examine towing shackles to see that they are securely fastened. Examine towing cable for frayed or broken condition. Make sure that cable is mounted securely when not in use.
(10) I tern 51, Hull and camouflage net. Inspect hull of vehicle for damage. Inspect camouflage net to see that it is properly secured and not damaged.
(11) Item 52, Glass. Clean glass in vision devices and lights, and inspect for damage.
66
39. After-Operation and Weekly Services
a. Purpose. After-operation Service is particularly important because at this time the driver inspects his vehicle to detect any deficiencies that may have developed, and corrects those he is permitted to handle. He should report promptly to the designated individual in authority the results of his inspections. If this schedule is performed thoroughly, the vehicle should be ready to roll again on a moment’s notice. The Before-operation Service, with a few exceptions, is then necessary only to ascertain whether or not the vehicle is in the same condition in which it was left, upon completion of the After-operation Service. The After-operation Service should never be entirely omitted, even in extreme tactical situations, but may be reduced to the bare fundamental services outlined for the At-halt Service if necessary.
b. Procedures. When performing the After-operation Service, the driver must remember and consider any irregularities noticed during the day, and in the Before-operation, During-operation, and At-halt Services. The After-operation Service consists of inspecting and servicing the following items. Those items of the After-operation Service that are marked by an asterisk (*) require additional weekly services, the procedures for which are indicated in subparagraph (Z>) of each applicable item.
(1) Item 54, Fuel, oil and water. Fill both fuel tanks. Check all level in engines and, if necessary, add oil to FULL mark on gage. Inspect level of coolant in both radiators and add as required, using antifreeze compound in freezing weather. If oil or water use is excessive, investigate cause.
(2) Item 55, Engine operation. Before stopping engine, accelerate and decelerate noting any unusual noise or irregular performance. Investigate any deficiencies noted during operation.
(3) Item 56, Instruments. Inspect all instruments to see that they are securely mounted, properly connected, and not damaged. Also see that they indicate or record the proper function of the units to which they apply.
Caution: Be sure to vent pressure radiator caps before removing to avoid serious injury from steam and hot water.
(4) Item 57', Siren. If tactical conditions permit, test siren operation and tone.
(5) Item 58, Glass. Clean all vision devices and glass and inspect for damage.
(6) Item 59, Lights. Clean all light lenses. Examine for broken parts and security of mounting. If tactical situation permits, open and close all switches and see that all lights respond properly.
(7) Item 60, Fire extinguishers. Inspect fixed fire extinguisher for tight mounting, damage, and leakage of valves or lines. Inspect
67
nozzles for proper aim, damage, and security of mountings and connections. Be sure wire seals are present and intact. Inspect portable extinguishers for good condition and security. See that wire is present and intact. Be sure nozzles are not clogged.
(8) Item 61, Decontaminator. Inspect decontaminator for full content, damage, and security of mounting. Remove filler plug to check contents.
(9) Item 62,* Battery. (a) Inspect battery for damage or leakage and security of mountings and connections. Top of battery, cables, terminals, and vent caps must be clean.
(Z>) Weekly. Add distilled water as necessary to bring electrolyte level one-half inch above top of plates. If distilled water is not available, any clean water is preferable to allowing cells to run dry.
Note. In low temperatures, do not add water until vehicle is about to be operated. Clean and tighten terminals if loose or dirty, and give them a light coating of grease.
(Id) Item 68, Accessories and belts. Open engine compartment door and inspect all accessible accessories for looseness and damage. Be sure fan and generator belts are in good condition and belt tension is %- to ’%-inch, finger-pressure deflection between pulleys.
(11) Item 6J±, * Electrical wiring, {a} Examine all accessible wiring conduits to see that they are properly connected and supported to hull.
(S) Weekly. Tighten all radio noise suppressor bond straps and accessible capacitor mountings and connections, and be sure suppressor units are secure.
(12) Item 65, Air cleaners, breathers, and vents. Inspect carburetor air cleaners and crankcase ventilator air cleaners for good condition and security of mountings. Inspect condition of oil and filter element. Clean and service if excessive dirt is present according to lubrication order (par. 33).
(13) Item 67, Engine controls. Inspect accelerator and hand throttle controls for security, damage, excessive wear, and free operation.
(14) Item 68, Tracks. Examine tracks for damage, excessive looseness, broken or missing connectors. Inspect track tension (par. 143). Adjust if necessary.
(15) Item 69, * Suspension. (a) Inspect suspension arms and compensating linkage for looseness or damage. Remove any foreign objects embedded in the tracks or between the wheels, sprockets, and suspension arms. Examine rubber tires for cuts, breaks, or separation from wheels. Be sure shock absorbers are secure and not leaking.
(Z>) Weekly. Tighten suspension assembly bolts, cap screws, and nuts and see that all securing wires or cotter pins are present and in good condition. Inspect guides, support rollers, compensating wheels, and sprockets for excessive wear or damage.
68
(16) Item 70, Steering brakes. Inspect brake levers for secure mounting, and linkage for excessive wear or damage and for free operation and secure holding of locking pawls. Investigate or report any deficiencies noticed during operation.
(17) Item 73, Leaks. Examine area beneath vehicle and floor of driving and engine compartments for oil, fuel, or coolant leakage.
(18) Item 7If., Gear oil levels. Check level of oil in transmissions, transfer unit and final drive housings and fill to proper level. Report any abnormal usage.
Caution: In checking transmission level, be sure to use correct procedure (par. 33).
(19) I tern 76, Fenders. Examine fenders and dust shields to see that they are in good condition and secure.
(20) I tem7 7 ,T owing connections. Examine the four towing shackles and pintle hooks to see that they are present, in good condition, and securely attached.
(21) Item78,Hull. Examine entire hull for damage from shellfire or collision. Inspect doors over driving compartment for good condition and proper operation of hinges and latches.
(22) Item 80, Vision devices. Inspect the periscope prisms and windows to see that they are in good condition, clean, secure in the holders, and that the holders are securely mounted. Inspect the spare periscope and their storage boxes to see that they are in good condition, clean, and secure.
Caution: Periscopes should be cleaned with a soft cloth or brush only.
(23) Item 81, Howitzer and mount. Winch, spade, and platform. Be sure that howitzer is secure in mount, clean, lightly oiled, and in condition for immediate use. Test manual howitzer elevating mechanisms and firing controls for proper operation. Check level of oil in elevating gear case. Be sure all exposed wiring is secure and undamaged. Examine packing glands, oil lines, piston and cylinder assembly, and drain plugs for leaks. Determine if manual traversing and electric and manual elevating mechanisms are in good condition and operate satisfactorily. Inspect winch and test for operation. Determine if cable is in good condition. Inspect spade and platform. Check hinges and fastenings. Determine if spade and platform are in good condition and operate satisfactorily.
(24) Item 82, * Tighten, (a) Tighten all items which require tightening as indicated by inspection.
(Z>) Weekly. Tighten the following: Gun mounting attachments, tools and equipment mounted on vehicle, ammunition cases, or any other units which require tightening on a weekly or mileage basis as indicated by inspection or experience.
69
(25) Item 83, ^Lubrication (weekly only). Lubricate all points which vehicle lubrication order indicates are necessary on a weekly or mileage basis, or any points which need additional lubrication as indicated by condition and experience.
(26) Item 8J>, ^Cleaning. (a) Remove all empty shell cases and refuse from gun mount. Clean all oil from driving compartment and floor of vehicle. Remove excessive mud and dirt from tracks and suspension system. See that grilles are not obstructed. Open bulkhead doors and clean radiator core air passages, if necessary.
(b) Weekly. Wash exterior of vehicle and remove all dirt and mud. If washing is impracticable, wipe as clean as possible and watch for bright spots that would cause glare. Wipe out all excess dirt, fuel, oil, or coolant drippings from engine compartment.
(27) Item 85, * Tools and equipment, (a) See that tools and equipment assigned to vehicle are present, in good condition, and properly stowed, or mounted.
(b) Weekly. Clean all tools and equipment. See that tools and equipment are in serviceable condition and that tools with cutting edges are sharp and properly protected. Properly mount or stow all items.
40. Battery Maintenance (Second Echelon)
a. Frequency. The frequency of the preventive maintenance services outlined herein is considered a minimum requirement for normal operation of vehicle. Under unusual operating conditions such as extreme temperatures, dust or sand, or extremely wet terrain, it may be necessary to perform certain maintenance services more frequently.
b. First Echelon Participation. The drivers should accompany their vehicles and assist the mechanics while periodic second echelon preventive maintenance services are performed. Ordinarily the driver should present the vehicle for a scheduled preventive maintenance service in a reasonably clean condition; that is, it should be dry and not caked with mud or grease to such an extent that inspection and servicing will be seriously hampered. However, the vehicles should not be washed or wiped thoroughly clean, since certain types of defects, such as cracks, leaks, and loose or shifted parts or assemblies are more evident if the surfaces are slightly soiled or dusty.
c. If instructions other than those contained in the general procedures in step (d) or the specific procedures in step (i) which follow are required for the correct performance of a preventive maintenance service or for correction of a deficiency, other sections of this manual pertaining to the item involved, or a designated individual in authority, should be consulted.
70
d. General Procedures. These general procedures are basic instructions which are to be followed when performing the services on the items listed in the specific procedures.
Note. The battery maintenance personnel must be thoroughly trained in these procedures so that they will apply them automatically.
(1) When new or rebuilt subassemblies are installed to correct deficiencies, care should be taken to see that they are clean, correctly installed, properly lubricated, and adjusted.
(2) When installing new lubricant retainer seals, a coating of the lubricant should be wiped over the sealing surface of the lip of the seal. When the new seal is a leather seal, it should be soaked in warm engine oil (OE 10) if practicable for at least 30 minutes. Then, the leather lip should be worked carefully by hand before installing the seal. The lip must not be scratched or marred. Caution must be exercised to insure installation of lip of seal in proper direction.
e. Definition of Terms. Refer to paragraph 34Z>.
f. Special Services. These are indicated by repeating the item numbers in the columns which show the interval at which the services are to be performed, and show that the parts or assemblies are to receive certain mandatory services. For example, an item number in one or both columns opposite a “Tighten” procedure means that the actual tightening of the object must be performed. The special services include the following:
(1) Adjust. Make all necessary adjustments in accordance with the pertinent section of this manual, special bulletins, or other current directives.
(2) Clean. Clean units of the vehicle with dry-cleaning solvent to remove excess lubricant, dirt, and other foreign matter. After the parts are cleaned, rinse them in clean solvent and dry them thoroughly. Take care to keep the parts clean until reassembled and be certain to keep dry-cleaning solvent away from rubber or other material which it will damage. Clean the protective grease-coating from new parts since this material is usually not a good lubricant.
(3) Special lubrication. This applies either to lubrication operations that do not appear on the vehicle-lubrication order or to items that do not appear on such orders, but which should be performed in connection with the maintenance operations if parts have to be disassembled for inspection or service.
(4) Serve. This usually consists of performing special operations, such as replenishing battery water, draining, and refilling units with oil and changing or cleaning the oil filter, air cleaner, or cartridges.
(5) Tighten. All tightening operations should be performed with sufficient wrench torque (force on the wrench handle) to tighten the
71
unit according to good mechanical practice. Use a torque-indicating wrench where specified. Do not overtighten, as this may strip threads or cause distortion. Tightening will alw’ays be understood to include the correct installation of lock washers, lock nuts, lock wire, or cotter pins provided to secure the tightening.
g. Special Conditions. When conditions make it difficult to perform the complete preventive maintenance procedure at one time, they can sometimes be handled in sections, planning to complete all operations within the week if possible. All available time at halts and in bivouc areas must be utilized, if necessary, to assure that maintenance operations are completed. When limited by the tactical situation, items with Special Services in the columns should be given first consideration.
h. Work Sheet. The numbers of the preventive maintenance procedures that follow are identical with those outlined on WD AGO Form No. 462, which is the “Preventive Maintenance Service Work Sheet for Full-track and Tank-like Wheeled Vehicles.” Certain items on the work sheet that do not apply to this vehicle are not included in the procedures in the manual. In general, the numerical sequence of items on the work sheet is followed in the manual procedures, but in some instances there is deviation for conservation of the mechanic’s time and effort.
i. Specific Procedures. The procedures for performing each item in the semimonthly and monthly maintenance procedures whichever shall occur first, are described in the following road-test chart. Each page of the chart has two columns at its left edge corresponding to the monthly and the semimonthly maintenance respectively. See WD Circular No. 36. Very often it will be found that a particular procedure does not apply to both scheduled maintenances. In order to determine which procedure to follow, look down the column corresponding to the maintenance due and wherever an item number appears, perform the operation indicated opposite the number.
Note. Those procedures preceded by an asterisk (*) require additional services at each third monthly service.
MAINTENANCE
ROAD TEST
Monthly Semimonthly
Note. Those procedures preceded by an asterisk (*) require additional road test, perform items 2, 3, 5, 9, 12, 13, and 15 which require little or no movement of the vehicle. When a road test is possible, it should be for preferably 3 and not over 5 miles.
Before-Operation Service
1 1 Perform the Before-operation Service outlined in
paragraph 36.
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MAINTENANCE
Monthly Semimonthly
Instruments and Gages
2 2 Observe readings of all instruments frequently dur-
ing operation to see whether they are indicating properly.
Oil-Pressure Warning Signal. In case of lighting of oil-pressure warning signal, vehicle should be stopped immediately and trouble corrected or reported to proper authority.
Engine Temperature Gages. Engine temperatures should rise gradually to normal range, 160° to 210° F., and gage should always indicate below 240° F. If gage indicates more than this, or if warning signal lights, stop vehicle until correction can be made.
Ammeter. The ammeter will register zero or slight discharge (—) with the engines idling, or register zero or slight positive charge ( + ) with engines running at operating speeds. Any unusual drop or rise in reading for an extended period may indicate a dangerously low battery or a faulty generator regulator.
Tachometers. Tachometers should indicate engine speed and accumulating revolutions without excessive noise or fluctuation.
Speedometer and Odometer. Speedometer should indicate vehicle speed. Odometer should register accumulating mileage without excessive noise or fluctuation.
Warning Lights. Transmission oil pressure warning lights should be off when engines are running faster than 450 revolutions per minute. Lights may flicker at slow idle speed.
Windshield, Windshield Wipers, and Siren
3 3 Inspect windshield assembly and wipers (when in
use) to see that they are in good condition, secure, and whether or not wiper blades move through their full stroke and contact surface evenly. Inspect siren for good condition and secure mounting and, if tactical situation permits, test for operation and tone.
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MAINTENANCE
Monthly Semimonthly
Brakes (Steering)
5 5 With vehicle stopped, pull back on steering brake
levers; if brakes are properly adjusted, levers should start to take hold at 6 to 8 notches of travel on ratchet. Accelerate vehicle to a moderate speed, release accelerator, apply both steering brakes, and observe whether or not they stop the vehicle effectively. Apply steering brakes independently, and see that they steer vehicle properly. Apply parking brake with vehicle on reasonable incline. It should hold vehicle effectively, and locking device should hold levers in applied position.
Transmission (Lever Action, Vibration, and Noise)
7 7 Operate vehicle through each speed range of trans-
mission. Observe whether or not selector lever operates properly and whether or not there are any unusual vibrations or noises in any speed range that might indicate damage, excessive wear, loose mountings, or improper operation.
Engine (Idle, Acceleration, Power, Noise, Smoke, and Oil Consumption)
9 9 Idle. With the vehicle stopped, observe if engines
run smoothly at normal idling speed, 450 revolutions per minute. Throughout road test, observe if there is any tendency of engines to stall when accelerator is released and hand throttle closed.
Acceleration, Power, Vibration, and Noise. Test engines for normal acceleration and pulling power in each speed. While testing in driving range, accelerate from low speed with wide-open throttle up to top speed and listen for unusual engine noise, knock, whine, or vibration that might indicate loose, damaged, excessively worn, or inadequately lubricated engine parts or accessories, or loose mountings or drive belts.
Smoke. During operation, observe if there is excessive smoke from exhaust.
Oil Consumption. Upon completion of road test, a check should be made to determine whether or not either or both engines have been consuming an excessive amount of oil.
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ROAD TEST—Continued
MAINTENANCE
Monthly Semimonthly
10 10 Unusual Noises (Propeller Shafts and Universal
Joints, Differential and Final Drives, Sprockets, Wheels, Support Rollers, and Tracks). During road test, listen for any unusual noise from these units, indicating damaged, defective or loose parts, or inadequate lubrication.
11 11 Temperatures (Transmission, Transfer Unit, Dif-
ferential, and Final Drives, Hubs, Sprockets, Wheels, and Support Rollers). After operating, remove bottom inspection plate and examine transmissions for excessive heat. Check by hand-feel for any abnormal temperature in transfer unit, differential and final drives, hubs of sprockets, wheels, and support rollers.
13
15
17
Note. If location on grade is selected for this check, time will be saved in performing item 12.
12 Gun Elevating and Traversing Mechanism. Place vehicle in a position where it will be tilted (sidewise) about 10°. Traverse gun mount through its full range, by hand controls, checking for indication of binding. With howitzer pointed forward, elevate it through its entire range with hand controls; check for binding, excessive lash, or erratic action.
13 Leaks. Look in engine compartment, and also beneath vehicle, for indications of fuel, oil, or coolant leaks.
15 Track Tension; Final Road Test. Inspect for satisfactory track tension after final road test (par. 143), and adjust if necessary.
MAINTENANCE OPERATIONS
Engine Crankcase (Leaks and Level)
17 Observe both crankcases for indications of oil leaks, and inspect bayonet gages for oil level. Add oil as necessary. If oil change is due or condition of oil warrants a change, drain and refill crankcases to proper level with specified oil. See lubrication order, paragraph 33.
Note. If oil is changed, do not start engines until new oil filter elements have been installed as in item 54.
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MAINTENANCE
Monthly Semimonthly
54
54
18
19
20
20
21
54 Engine Oil Filters. Inspect oil filters to see that they are in good condition, secure, and not leaking. .Drain off accumulated sediment from filter bowl.
Clean and Serve. Remove oil filter elements, clean cases, and install new filter elements, using new gaskets and tightening covers securely. See lubrication order, paragraph 32.
18 Side Armor (Fenders, Dust Shields, Guards, Paint
and Markings, Shackles, and Siren) . Inspect these items to see that they are in good condition, that armor, fenders, dust shields (if so equipped), guards, shackles, and siren are secure and that towing shackles are not excessively worn. Observe condition of paint for rust or polished surfaces that may cause reflections, and (unless covered for tactical reasons) see that all vehicle markings are legible.
19 Bottom (Armor, Inspection Plates, and Drain Plugs). See that these items are in good condition and secure, and that bottom drain plugs are tight. Tighten all bottom inspection plates securely.
20 Differential and Final Drives. Inspect housings for good condition and leakage; check lubricant level. See that all assembly and mounting bolts are secure. If change of lubricant is due, or condition of oil warrants a change, drain and refill with specified oil at this time. See lubrication order, paragraph 32.
Tighten. Tighten all external assembly and mounting bolts securely.
21 Tracks (Shoes, Shoe Pins, and Bushings). Inspect tracks to see that these items are in good condition, correctly assembled, secure, and not excessively worn. Tighten track screws to 80 to 90 foot-pounds.
*Note:
Whenever the tracks are disconnected and removed from the sprockets, support rollers, and wheels, or at each third monthly maintenance service, the related items 22 and 25 marked on the Preventive Maintenance Service Work Sheet WD, AGO Form 462 should be inspected as described below in the asterisk-marked (*) procedures. On the regular semimonthly and monthly maintenance services, the tracks should not be removed unless repairs are needed.
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MAINTENANCE
Monthly Semimonthly
Caution: Whenever tracks are removed for repair or replacement, do not reinstall tracks until the services followed by the asterisk (*) in items 22 and 25 have been completed.
22 22 Compensating (Wheels, Arms, Adjustment, Lock
Nuts). Inspect these items to see that they are in good condition, correctly assembled, secure, and that grease is not leaking excessively from wheel bearing seals. Be sure adjusting nuts and adjusting locks are secure. Tighten all assembly and mounting bolts and nuts securely.
♦Note:
22 In addition to the above, at each third monthly
maintenance service or whenever the tracks are removed, check the compensating wheel hub bearings for looseness or end play. Spin the wheels and listen for any unusual noise that might indicate a damaged, excessively worn, or inadequately lubricated bearing.
23 23 Bogie (Arms, Shock Absorbers, Links, Brackets).
Examine above components to see if they are in good condition, correctly assembled, securely mounted, and not excessively worn. Inspect shock absorbers for leaks.
23 Tighten. Draw up all suspension unit assembly
or mounting nuts or screws securely.
24 24 Wheels (Tires, Support Rollers). Inspect wheels
and rollers for good condition, correct assembly, and secure mounting. Pay particular attention to see that tire rubber has not separated from rim and that tires are not cut, torn, or excessively worn. Inspect for excessive lubricant leaks from bearings.
24 Tighten. Jack up track wheels and test bearings
for looseness, roughness, and end play. Spin wheels and listen for any unusual noise. Tighten assembly and mounting bolts securely.
24 Note. Whenever the tracks are removed, the above operation
should be performed before the tracks are reinstalled.
25 25 Sprockets (Hubs, Teeth, and Nuts). Inspect
sprockets for good condition, correct assembly, and security of mounting bolts. Inspect sprocket teeth for excessive wear, and shaft flange gaskets or oil seals for excessive leaking of lubricant. If sprocket teeth
752022 0—47-----6
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MAINTENANCE
Monthly Semimonthly
25
26
27
28
30
30
32
are excessively worn, sprockets should be replaced or reversed. Tighten assembly and mounting bolts securely.
Note. In addition to the above, at each third monthly operation, or whenever the track is disconnected and removed from the sprocket, check the sprocket teeth for excessive wear, see that sprockets are well secured to hubs and that the hub-to-final drive bolts are secure. Check the sprocket hub bearings for looseness and end play. After performing the above, reinstall the tracks and connect them securely.
26 Track Tension. Adjust track to standard tension (par. 143).
27 Top Armor, Hull, Deck, Paint and Markings, Grilles, Doors, Latches, and Antenna Mast. Inspect these items to see that they are in good condition and secure. See that door hinges and latches operate properly, are not excessively worn, and are adequately lubricated. Be sure grilles are not obstructed. Examine paint for rust spots or polished surfaces that may cause reflections and, unless covered for tactical reasons, see that vehicle markings are legible.
28 Caps and Gaskets (Fuel and Radiator). Inspect to see that fuel tank and radiator caps and gaskets are in good condition, secure, and not leaking.
Engine Removal (When Required).
Serve. Remove engines on monthly maintenance service only if inspections made in items 9, 10, 13 and a check of oil consumption indicate a definite need.
30 Clean. Clean exterior of engine and dry thoroughly, taking care to keep dry-cleaning solvent away from electrical wiring, terminal boxes, and equipment.
Note. In this and following services (items 32 to 60), the procedures should be followed in the best possible manner if engines are not removed from vehicle.
Spark Plugs (Gaps and Deposits). Remove and clean spark plugs. Inspect insulators for cracks or breaks and electrodes for excessive burning. Replace unserviceable plugs with new or reconditioned plugs. Adjust electrodes of all plugs to be installed to 0.030 inch by bending grounded electrodes. Be sure to install new gaskets and do not overtighten plugs.
^ote. Perform item 33 before reinstalling plugs. Inspect the spark plug resistor-suppressors for scorching and cracks and be sure all connections are secure.
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ROAD TEST—Continued
MAINTENANCE
Monthly Semimonthly
33 Compression Test (Record). When spark plugs
are removed for performance of item 32, test compression of each cylinder and record gage readings on WD AGO Form No. 462. If there is more than 10 pounds variation between cylinders, report to designated authority.
34 34 Generators and Starters. Inspect generators and
starters for good condition, security of mounting, and secure wiring connections. Remove commutator inspection covers and examine commutator for good condition. See that brushes are free in brush holders, clean and not excessively worn, that brush connections are secure, and that wires are not broken or chafing. Clean commutator end of units by blowing out with compressed air. Tighten mounting bolts securely. Inspect generator armature brush capacitors to see that they are in good condition and securely connected.
36 36 Distributors. Inspect distributor bodies and ex-
ternal attachments and radio noise resistor-suppressors for good condition and secure mountings. Clean caps, rotors, and seals, and inspect for good condition and correct assembly. Look for cracks or burns. Inspect breaker points for good condition, good aline-ment, and a 0.015-inch gap. If the breaker plate assemblies are unserviceably dirty, remove the distributor, clean in dry-cleaning solvent, dry with compressed air, lubricate the parts as specified below for the monthly maintenance service, and reinstall the distributors in correct position for timing. When cleaning distributors, remove wicks and lubrication cups, clean, and dry while removed and reinstall them only after the distributor assemblies are cleaned and blown dry with compressed air. If the breaker points are pitted, burned, or worn to an unserviceable condition, install a new set. If points are badly pitted, test condenser connections for tightness, and if tight replace condenser also. If points are slightly pitted or burned, dress with point file or 2/0 flint paper and blow off filings with compressed air.
Shaft. Check shafts by hand-feel for looseness to determine whether or not the bushings are worn.
Centrifugal Advance. Test range of movement of centrifugal advance mechanism by rotating shaft
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MAINTENANCE
Monthly Semimonthly
and rotor by finger force. Observe whether or not shaft returns to original position without binding.
36 Special Lubrication. Lubricate cam surfaces,
movable breaker-arm pin and camshaft sparingly with general-purpose grease, and the wick with a few drops of engine oil (OE 10).
Note. Keep lubricant off the distributor points; do not apply more lubricant than is specified; and wipe the cam clean before lubricating its surface.
See lubrication order, paragraph 32.
36 Adjust. Adjust breaker-point gap to 0.015 inch at
wide-open position.
38 38 Ignition Wiring and Conduits. Inspect accessible
ignition wiring and conduits for cleanliness, good condition, correct assembly, secure mounting, and see that they are not chafing against other engine parts.
39 39 Coils. Inspect ignition coils and radio noise sup-
pressor capacitors and be sure they are clean and that all mountings and connections are secure.
42 42 Breather Caps and Ventilators. Inspect engine
crankcase ventilator oil bath air cleaner for good condition and correct assembly. Clean oil bath air cleaner, reoil and reinstall securely. See lubrication order, paragraph 32.
43 43 Air Cleaners (Carburetors). Disassemble, clean,
reoil, and reinstall carburetor air cleaners following carefully the correct procedure outlined in lubrication order, paragraph 32.
44 44 Carburetors (Automatic Chokes, Throttles,
Linkage). Inspect these items to see if they are in good condition, correctly assembled, and securely installed ; that carburetors do not leak; that control linkage, automatic choke, and throttle shafts are not excessively worn. Inspect automatic chokes for closed position when engine is cool. See that throttle valves open fully when accelerator is fully depressed. Remove the fuel cleaner strainer from each carburetor fuel inlet, clean in dry cleaning solvent, and reinstall. Tighten knurled nut finger-tight; do not use pliers.
45 45 Manifolds (Intake and Exhaust). Inspect ac-
cessible portions of manifolds for good condition, secure mountings, and for possible leaks.
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MAINTENANCE
Monthly Semimonthly
45 Tighten. Tighten manifold assembly mounting
nuts and cap screws to 25-30 foot-pounds torque.
46 46 Cylinder (Heads and Gaskets). Inspect cylinder
heads for good condition and secure mounting. Note any indications of oil, coolant, or compression leakage around cap screws or gaskets.
Caution: Cylinder-head cap screws should not be tightened unless there is a definite indication of looseness or leaks. If tightening is necessary, a torqueindicating wrench must be used and screws tightened in proper sequence (fig. 51) to 70-75 footpounds.
49 49 Water Pumps, Fans, and Shrouds. Observe
whether or not these items are in good condition and securely mounted. Be sure fan blades do not interfere with shrouds or cores. See that the drive belts and pulleys are well alined; belts not excessively worn, frayed, oil soaked, improperly adjusted, or bottoming in drive pulleys. Adjust to %- to %-inch fingerpressure deflection.
51 51 Engine Compartment (Bulkhead and Control
Linkage). See that engine compartment including bulkhead is in good condition, clean, and secure; and that control linkage in the engine compartment is in good condition, and securely connected and mounted.
51 Clean. Clean engine compartment as thoroughly
as possible. Whenever engines are removed, clean out all fuel and oil drippings, dirt, and refuse; wipe out the engine compartment with cloths soaked in dry cleaning solvent, and dry thoroughly.
53 53 Fuel (Tanks and Lines). Inspect accessible por-
tion of these items for correct assembly, good condition, and secure mounting. Note whether or not there are indications of fuel leaks from tanks or lines. Drain water and sediment from each tank by removing drain plugs and allowing fuel to drain briefly until it runs clean. Tighten plugs and fuel tank drain-hole cover securely to prevent fuel and dust leaks.
Caution: Catch drainings in container and use every precaution not to spill fuel. If fuel does spill, wipe up until dry before turning on the main battery switch.
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MAINTENANCE
Monthly Semimonthly
53 Tighten. Tighten accessible fuel line support clips
securely.
56 56 Oil Coolers (Transmission and Differential).
Examine differential oil cooler and lines, and transmission coolant lines for good condition, secure attachment and for leaks. Inspect differential oil cooler to see that core is not clogged with dirt and trash; clean out foreign material.
57 57 Exhaust Pipes and Mufflers. Inspect these
items for good condition, secure assembly, and mounting of exhaust pipes and mufflers and for indications of exhaust leaks.
57 Tighten. Tighten all accessible mounting bolts
and connections securely.
58 58 Engine Mountings. Inspect all engine mountings
and radio bond straps to see that they are in good condition and secure.
58 Tighten. Tighten all mountings and brackets se-
curely. When engines are removed, tighten the mount-to-engine and bracket-to-hull bolts securely.
60 60 Fire Extinguisher System (Tank, Valve, Lines,
Nozzles, and Mountings). Inspect cylinder and valve of fire extinguisher system for good condition, secure mounting, and full charge. Full charge may be observed by presence of intact wire seal, but can be positively determined only by weighing. Examine control cables to see that they are in good condition and free to operate at a moment’s notice. See that all lines and nozzles are in good condition, securely mounted and connected, with nozzles properly aimed and not clogged. If dirty or corroded nozzles are found, disconnect main feed line and blow out cautiously with compressed air.
Note. Empty, or partially empty, cylinders should be reported for recharge or replacement immediately.
Caution: Do not drop, strike, or roughly handle extinguisher cylinder, nor expose to excessive heat.
Special Lubrication. Apply a few drops of oil to pulleys and guides through which control cables operate.
60 Tighten. Tighten all assembly and mounting bolts
and screws.
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MAINTENANCE
Monthly Semimonthly
61 Engines (Install Mountings, Lines and Fit-
tings, Wiring, Control Linkage and Oil Supply). Reinstall removed engines according to instructions in paragraph 68. Take care to tighten mountings securely and to connect properly all fuel, oil, and coolant lines, wiring, and control linkage which were disconnected when engine was removed. Adjust control linkage. Be sure to refill engine crankcase with specified oil.
62 62 Radiators (Core, Mountings, Hose, Antifreeze,
and Records). Inspect these items for good condition, correct assembly, and for leaks. See that radiator mountings and hose and tubing connections are secure. Clean insects and refuse from external air passages of cores. Remove radiator if necessary. Test strength of antifreeze if in use. Examine coolant to determine whether or not it is contaminated with rust, oil, or other foreign matter to the extent that the cooling system should be cleaned. If inspection indicates cleaning is necessary, proceed according to paragraph 115, and current directives regarding proper procedures, cleaner, neutralizer and inhibitor. Refill radiator with proper coolant. Do not fill to top but allow room for expansion. On radiators w’hich are removed, perform this inspection partly while removed from the vehicle, and partly after replacement, as necessary to make the complete inspection properly.
Serve. Reinstall all removed radiators. Take care to tighten mountings, and hose or tubing connections securely. Fill the cooling system afterward, adding antifreeze or inhibitor as required and recheck the cooling system for leaks.
63 63 Battery (Cables, Hold-Downs, Battery Compart-
ment, Record of Gravity, and Voltage). Inspect battery case for cracks and leaks. Clean top of battery. Inspect cables, terminals, bolts, posts, straps and hold-downs for good condition. Test specific gravity and voltage and record on WD AGO Form 462. Specific gravity reading below 1.225 indicates battery should be recharged or replaced. Electrolyte level should be above top of plates and may extend one-half inch above plates.
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MAINTENANCE
Monthly Semimonthly
63 Serve. Perform high rate discharge test according
to instructions for “condition” test which accompany test instrument. Cell variation should not be more than 30 percent.
Note. Specific gravity must be above 1.225 to make this test.
63 63 Clean. Clean entire exterior of battery and interior
of battery box. Repaint box if corroded. Add distilled water to one-half inch above cell plates. Clean battery terminal, terminal bolts and nuts, and battery posts. Inspect bolts for serviceability and grease lightly. Tighten terminals and hold-downs carefully to avoid damage to battery.
Note. Close main battery switch and open fuel shut-off valve at this time.
64 64 Accelerators (Linkage and Dual-Throttle Syn-
chronization ). See that accelerators and all of their connecting linkage are in good condition, and securely connected. Press the accelerators down fully to see whether or not the carburetor throttles open fully. Check synchronization of throttle linkage at each carburetor to see that throttle valves open and close together. After starting engines, test to see that throttles are so adjusted that, at idle speed (450 revolutions per minute), the variation between the two engines will be no more than 50 revolutions per minute and at 1,000 revolutions per minute there will be no more variation than 100 revolutions. Inspect throttle control linkage to see that it is properly adjusted.
64 Adjust. Adjust throttle control linkage (par. 110).
65 65 Starting Motors and Instruments. Start en-
gines, observing all starting precautions outlined in item 1. Note whether the general action of the starters is satisfactory, particularly whether or not the drives engage, operate properly without excessive noise, and have adequate cranking speed. Observe whether each engine starts readily. As soon as the engines start, observe whether or not all instruments operate properly, and particularly if the oil pressure signal and ammeter indications are satisfactory.
67 67 Ignition Timing. With engine running, determine
whether or not ignition timing of each engine is cor-
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Monthly Semimonthly
ROAD TEST—Continued
68
68
69
70
rect, according to instructions (par. 73). Also observe whether or not automatic controls advance the spark as engine is accelerated gradually. When necessary, adjust ignition timing to specifications (par. 73), taking care to see that distributor is well secured when adjustment is complete.
Caution: Be sure that distributor timing is properly adjusted for efficient engine performance with grade of fuel being used.
68 Regulator Unit (Connections, Voltage, Current, and Cut-Out). See that regulator units and the radio noise suppression capacitors and bond straps are in good condition, and that mountings and connections are secure.
Connect low-voltage circuit tester to regulator and observe whether or not voltage regulator, current regulator, and cut-out control the generator output properly. Follow instructions in vehicle manual, or those which accompany test instrument.
Caution: Make test only after regulator has reached normal operating temperature.
69 Engine Idle. Adjust engine mixture and throttle stop to obtain smooth operation at 450 revolutions per minute. See paragraph 110.
70 Throttle Synchronization. Depress accelerator slowly and observe whether or not tachometers of both engines indicate within 50 revolutions at 450 revolutions per minute and within 100 revolutions at 1,000 revolutions per minute. At the conclusion of this maintenance service, allow engines to cool properly by operating at 450 revolutions per minute from 3 to 4 minutes before stopping them.
71 Gun Mount (Paint, Seats, Stowage Boxes, Ammunition Boxes, Clips, and Racks). Inspect to see that these items are in good condition, and securely assembled and mounted; that mount is clean, and that paint is in satisfactory condition; that adjusting mechanism of seats operate properly, and are adequately lubricated. Pay particular attention to see that shell hangers and dividers are all present and properly installed in ammunition boxes.
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MAINTENANCE
Monthly Semimonthly
73 73 Periscopes. Examine periscope prisms and win-
dows to see that they are in good condition, clean, secure in holders, and that holders are securely mounted; that lever and locking devices operate freely and are not excessively worn; that their traversing and elevating devices are free and not excessively worn. Examine spare periscopes and their stowage boxes to see that they are in good condition, clean, and secure.
Caution: Prisms should be cleaned only with a soft cloth or brush.
75 75 Brakes (Steering Levers, Linkage, and Shafts).
Inspect steering brake levers, linkage, and shafts to see that they are in good condition, securely mounted, properly connected, and not excessively worn. Apply steering brake levers and observe whether they begin to take hold at 6 to 8 notches of travel on ratchet.
75 Tighten. Tighten all assembly and mounting nuts
and screws securely.
77 77 Differential. Examine accessible part of the dif-
ferential case in driver’s compartment to see that it is in good condition, that all mounting and assembly bolts and cap screws are secure, and that there are no oil'leaks.
78 78 Transmissions. Inspect transmissions to see that
they are in good condition, securely mounted, and not leaking. If condition or level of lubricant indicates necessity for oil change, drain and refill to correct level with specified oil. See lubrication order, paragraph 32.
78 Adjust. Adjust transmission front band (para-
graph 122).
79 79 Transfer Unit (Seals and Leaks). Inspect the
transfer unit to see that it is in good condition, securely assembled, and mounted. Note whether oil is leaking from the case of seals. If condition or level of lubricant indicates the necessity for oil change, drain and refill to correct level with specified oil. See lubrication order, paragraph 32.
79 Tighten. Tighten all external assembly and
mounting bolts and cap screws securely.
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Monthly Semimonthly
80
81
81
85
86
80 Transmission and Transfer Unit Controls and Linkage. See that control levers and linkage for these units are in good condition, correctly assembled, and securely connected and mounted. See that joints are adequately lubricated and not excessively worn.
81 Propeller Shafts (Universal Joints, Alinement, and Yokes). Inspect propeller shafts for good condition, correct and secure assembly. See that universal joints are not excessively worn and inspect for adequate lubrication. Look for excessive leaks at seals of universal joints and at sliding joint.
Tighten. Tighten all universal joint assembly and yoke cap screws securely.
85 Lights and Switches (Head, Tail, Blackout, and Internal) . If tactical situation permits, test switches and lamps (lights) to see that they operate properly. Inspect all lights for good condition, secure mounting, for broken lenses, and discolored reflectors.
86 Wiring (Junction and Terminal Blocks and Boxes). Inspect to see that all exposed electrical wiring and conduits, terminal blocks, and boxes are in good condition, well supported, and securely connected. Be sure radio noise capacitors and/or wiring support clip bondings are in good condition, clean, and securely mounted or connected.
88 Radio Bonding ( Suppressors, Filters, Condensers, and Shielding). See that all units not covered in the foregoing specific procedures are in good condition and securely mounted and connected. Be sure all additional noise suppression bond straps and internal and external toothed lock washers listed in paragraph 106 are inspected for looseness or damage, and see that contact surfaces are clean. If objectionable radio noise from vehicle has been reported, make tests in accordance with paragraph 48. If cleaning and tightening of mountings and connections and replacement of defective radio noise suppression units does not eliminate the trouble, the radio operator will report the condition to the designated individual in authority.
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ROAD TEST—Continued
ARMAMENT
Howitzers: 155-mm. Howitzer (Mounts, Traversing, and Elevating Mechanism, Firing Controls)
MAINTENANCE
Monthly Semimonthly
126 126 Inspect to see that these items are in good condition,
clean, well lubricated, correctly and securely assembled, and not excessively worn. Check to see that firing controls are in good condition and secure. Operate firing controls to see that they function properly. Operate hand-elevating controls through entire range, to see that they function properly. Traverse mount by hand to see if there is any binding, and that mount can be turned through its entire range (17° left-210 right). Inspect electric elevating mechanism including motor, limit switch, wiring and operating control switch to see that they operate properly, are in good condition, correctly assembled, secure, and not excessively worn. Add oil to elevating gear case if required. Make an operating check of power-elevating mechanism moving motor switch to either UP or DOWN or MANUAL position (fig. 17) to see if gun responds properly and any over-run is properly controlled. Tighten all assembly and mounting bolts and screws securely.
TOOLS AND EQUIPMENT
130
131
132
Tools (Vehicle Kit and Pioneer)
130 Check vehicle and pioneer tools to see that all items are present, in good condition, and properly stowed or mounted. Any tools mounted on outside of vehicle, having bright or polished surfaces, should be painted or otherwise treated to prevent glare or reflections. Tools with cutting edges should be sharp and edges should be protected.
131 Equipment. Check special equipment items against vehicle stowage lists to see if they are all present, in serviceable condition, and properly stowed or mounted.
132 Spake Track Blocks. Inspect to see if they are all present, in good condition, and properly stowed or mounted.
88
ROAD TEST—Continued
MAINTENANCE
Monthly Semimonthly
133 133 Spare Oil Supply (Recoil, Hydraulic, Engine).
Check to see that supply of listed spare oil is present and properly stowed. This supply should be maintained at all times.
134 134 Decontaminator. Examine decontaminator to see
that it is in good condition, secure, and fully charged. Make latter check by removing filler plug.
135
136
137
138
139
Note. The solution must be renewed every 3 months as it deteriorates.
135 Fire Extinguisher (Portable). Inspect extinguisher to see if it is fully charged, in good condition, securely mounted, and if seal on valve head is intact. Weigh cylinder to determine if it is fully charged.
136 Publications and Form No. 26. Check to see whether vehicle manuals, Lubrication Order, Accident-Report Form No. 26 and Form No. 478, MWO and Major Unit Assembly Replacement Record are present, legible, and properly stowed.
137 Vehicle Lubrication. Perform a complete lubrication service on the vehicle according to instructions in lubrication order, paragraph 33, omitting only those items which have received attention in the foregoing specific procedures. Replace damaged or missing fittings, lines, or plugs.
138 Modifications (Modification Work Orders Completed) . Inspect vehicle to determine that all Modifications Work Orders have been properly completed and entered on Form No. 478. Enter all modifications or major unit assembly replacements made at time of this service.
139 Final Road Test. Make a final road test, rechecking items 2 to 15, inclusive. Recheck transmission and differential to see that lubricant is at correct level and that there are no leaks. Confine this road test to the minimum distance necessary to make satisfactory observations. While testing vehicle, operate it in a normal manner.
Note. Correct or report any deficiencies found during final road test to designated authority.
89
Section XV. TROUBLE SHOOTING
41. General
a. This section contains trouble-shooting information and tests which can be made to help determine the causes of some of the troubles that may develop in vehicles used under average climatic conditions (above 32° F.). Each symptom of trouble given under the individual unit or system is followed by a list of possible causes of the trouble. The tests necessary to determine which one of the possible causes is responsible for the trouble are explained after each possible cause.
b. When trouble shooting, first turn to the subparagraph pertaining to the condition at hand, and then perform the various tests in the order listed. This is important because the tests which are easiest to perform and conditions most likely to occur are listed in their respective order.
42. Engine
a. Starter Does Not Crank Engine. (1) Open switch in starting circuit. In order to complete the starting circuit, the emergency ignition switch and the regular ignition switch, as well as the master battery switch, must be ON. Make sure that all of these switches are turned on.
(2) Battery ground circuit open. Turn on lights. If lights do not light, battery ground circuit is open or master switch is inoperative. Check ground circuit and switch with test lamp or voltmeter (fig. 39).
(3) Loose connection in starting circuit. If lights go on properly, press starter button; then if lights go out, there is a poor connection at the terminals, at the batteries, at the ground strap, at the master switch, or at the starter (fig. 37). These can be checked by a voltmeter between each successive terminal and ground. Clean and tighten loose connections, replace broken ground straps, or replace defective master switch.
Note. All wires in the vehicle are marked at all connecting ends with the circuit number, and these circuit numbers appear in all of the wiring diagrams in this section.
(4) Battery run down. If lights dim considerably when starter button is pressed, but still burn, batteries are low. Test batteries with a hydrometer and a high-rate discharge tester, if available. Replace any battery units that do not test satisfactorily.
(5) No ground in starter relay circuit. When the starter button is first pressed, the starter relay circuit is grounded through the transmission oil pressure warning signal switch (fig. 37). If lights do not dim at all, and transmission warning light on the instrument panel does not light, the signal switch is probably defective. A test can
90
.............J i ।---- -------- apparatus box f............U-------------------------------------------------—r_^_1
W ) TO R- H- REGULATOR r^rjl. Vw1 RELAY SHOWN
INSTRUMENT PANEL L. H. REGULATOR—4 BREAKER | | |~T Bl ’°° FR°M POSITION
NOU ORANGE / I I " ^A^ | TO R. H. TO GUN
NBOLACKOTRAn?)E—/ fl I NO. 16 RED Q J, J S™TER
F,~ Sg| \ ■ -—A BLACK TR- <93l X.H /
C1\D O O | IB \ :~b □ \ N°- 14/LACK |94-2941 rTciI
ohhnn ^■(G,4) ’ hi TO battery^vvt
LEFT IGNITION |W H / W 5z"fG-j|SWITCH — REAR
SWITCH-/ X--------- L. H. REGULATOR /_LIU- \ , TERMINAL I
CIRCUIT BREAKER I 11W\\ // PUSH BUTTON BLOCK-► (V-Zl——_B
RIGHT IGNITION K/Z z—/\\ Xx || 1 \\ I ,_____IsoiFNOID \\ NO. 10 RED (74)— - \
SWITCH-/ I H X\ NO. 14 ORANGE T \ = _F ,-A(74) 11 16 RED BLACK TR. (93) \\
Q®)J D(72-93)^g^E (74-274) 10 RED j74) \\
M kJ , m NO. 14 ORANGE BLACK TR. (14) *- H- STARTER \\
/ / W __^-L H. TRANS. OIL SIGNAL SWITCH Z7q\ I /~7~x\\
II H /7~\\ n llu © / i nil I
z—IGU)-1 ZH ( W
y\()r--------yNO. 10 RED (74-274) VS VGA VL. \ V///
>7 / --NO. 16 GREEN BLACK TR. (72-93) \\ (K?v
j=) l ® \ **** TA 3 X
\ ®L X | tSjU 1\ I CONDENSER—"S PT| I BLACK TA (212)° & ®[C OT/nTT[ \l
'>71 < H fl \ Uc ?
-Fu|____________1 MB? JI 4 \
EMERGENCY ignition \T A primary V-C
SWITCH BOX XO /gf A X w I (MINUS 7=T
I M / kRl terminal) /II
/ \ SlBW W / FEED W'REJ^ RIGHT distributor/^
kNEL g H / DISTRIBUTORS
I i 8® 1 IL ZNO- 14 NAT. RED &
Olw T J) BLACK Tr. (212)
TR. (211) A LEFT DISTRIBUTOR CAP^ft—-y^
T L »l
INT OF VEHICLE C('2)ffib SECONDARY ^T)
W HIGH TENSIONi'y/TA U^) ©k
C7 feed from resistor \ J
14 NAT. RED TR. (12) O g (PLUS TERMINAL)-HS\ | CONDENSER-^-fm
(^^C{'2) A left ignition coil—a \ I
W 1 ^^7-NO. 14 NAT. RED TR (12B \^R /
LIGHTING CIRCUIT BREAKER 1/ ® / A \ V / r‘
M ^fea /MX primary iV—(
II JgL \ "L, g I (MINUS /T
V 'W—- - 1 njy TERMINAL) /| |
]K FEED WIRE-* /
® LEFT DISTRIBUTOR^
Figure 38. Ignition circuit.
752022 0—47-----7
pounds or more. If the compression pressure at cranking speed falls below 95 pounds, notify higher authority.
(6) Pistons, rings, or cylinders worn. Check compression pressure. If pressures vary considerably, or if all cylinders are low, notify higher authority.
e. Engine Overheats. (1) Low level of coolant. Check level of coolant and fill to correct level with water or antifreeze. Also check system thoroughly to determine cause of coolant loss (par. 49).
(2) Belts loose or broken. The belts drive the generator, water pump, and fan. Inspect belts and, if necessary, adjust to obtain %-to %-inch slack measured as shown in figure 47.
Note. Belts are matched in sets. If one belt is broken, all three belts must be replaced at the same time.
(3) Radiator air inlet plugged. Open ventilating sliding doors on bulkhead (fig. 13). Check radiator core air passages to see if plugged with dirt, leaves, or twigs. Clean out. See that inlet and outlet grilles on top of vehicle are not covered with tarpaulin or other equipment. Remove screen from inlet grille and clean.
(4) Mechanical failure in cooling system. Check thoroughly as outlined in paragraph 49.
(5) Ignition timing late. Check and reset ignition timing (par. 73).
(6) Engine oil level low. Check oil supply and add to the correct level.
(7) Radiator thermostat sticking. Replace thermostat (par. 117).
/. Engine Operates Noisily, (1) Light knock or ping on acceleration. Check grade of gasoline used; it should be 80 octane. Check or reset ignition timing (par. 73). Remove cylinder heads and clean carbon (par. 60).
(2) Clicking noises synchronized with camshaft speed. Check oil level; an overfilled crankcase will cause oil to foam and valve lifters to become noisy. Drain oil to correct level. Check conditions of crankcase oil and change oil if dirty or gritty.
(3) High-pitched squeals. Inspect fan, generator, distributor, and water pump for underlubricated or frozen bearings. Lubricate or replace unit, as required.
(4) Heavy knocks synchronized with crankshaft speed. Crankshaft or connecting rod bearings burned out. Notify ordnance personnel.
g. Engine Oil Pressure Low (Warning Light Stays On). (1) Low oil level. Check oil supply and add oil to the full mark on gage.
(2) High oil level. If oil level is high (above the full mark), it may be an indication that the fuel pump switch has been left on while the engine has not been running and raw gasoline has passed through the carburetor and manifolds and into the crankcase, causing oil dilution
94
and low oil pressure. Drain crankcase and install fresh oil (par. 33). Overfilling of crankcase should be avoided at all times.
(3) Oil worn out or incorrect grade. Check log book entries for mileage of last oil change and grade of oil used. Refill with correct grade of engine oil.
(4) Broken line to valve lifters.' Inspect oil feed line from side of cylinder block to valve lifter connection at center of vee, and replace if cracked or broken. Replenish oil.
(5) Oil pressure warning signal switch defective. If no cause of low oil pressure can be found, the trouble may be in the oil pressure warning signal switch at the rear of the engine. Replace switch (par. 97).
(6) Worn oil pump gears. Remove oil filter inlet pipe at front of cylinder block and install pressure gage. If pressure is below 12 pounds with engine idling, notify ordnance personnel.
43. Ignition System
a. No Spark in One Cylinder. (1) Spark plug wiring faulty. Make visual inspection of wiring to determine if disconnected, broken, or shorted. Reconnect, repair, or replace as required. Check current to plug by cranking engine with wire disconnected and terminal at I end of ceramic insulater held one-fourth inch from cylinder head. If no spark jumps, wiring is shorted or broken and must be replaced.
(2) Spark plug faulty. If strong spark jumps with above test, fault is in plug. Remove plug and inspect for cracked insulator, broken electrodes, fouling, or incorrect gap. Clean, readjust, or replace as required.
b. No Spark to Any Cylinder. (1) Distributor cap faulty. In-Ispect distributor cap for loose mounting, moisture, dirt, or cracked or burned condition, and dry off, clean, or replace as necessary.
(2) Wiring defective. Inspect high-tension wire and low-tension i wire from distributor to coil, and back through feed circuit (fig. 38).
(3) Contact points inoperative. Remove distributor cap and inspect contact points for gap, burned condition, and spring tension. Service or replace in accordance with instructions (par. 70).
(4) Defective coil or condenser. Check coil and condenser with instruments or by substitution, and replace one or both units as required.
44. Battery Circuit
a. No Current in Battery Circuit. (1) Master switch open. Close master battery switch.
(2) Loose cable connections. Inspect all cable connections at battery, apparatus box, and terminal blocks (fig. 39) and clean and tighten if necessary.
95
APPARATUS BOX-i .-STARTER RELAYS
7 B Q0C-JQC20<^nW^NO 1 BLACK(811 ------------------FRONT OF VFH,CLE
3 Q IIW R. h. BATTERY (12 VOLT)
circuit! OCZXU
BREAKERp^J’0^'-:.';; H/l ----------------- 1
(“ JI ™/o1l n i—B , TO RIGHT REAR
| I ______________NO, 4 RED (81)____£/________LX J NO. 1 BLACK (81) DOMELIGHT
feggP1 / ■£> yi
I L-AMMETER SHUNT _ I
APPARATUS BOX co NO. 8 RED I
TERMINAL BLOCK — ♦
o ■ ^11
r—BATTERY CHARGING | TO R. H. STARTER H Z/.._ „
\ OUTLET \ H /NO' 2
\ ouilei _ \ __ga^r BlACK
\ MASTER BATTERY z XQM
\ SWITCH g(| J /
\ I fr . ______J-J TO GUN
\ n 1 ’rr i j_RQ) control
\ LZ | / X BOX
X\ QOCZZDOCUD^^ L.H. starter
T~~?j7 ^XX ^L. H. BATTERY (12 VOLT) |
11 X\ Xx ———-^1
XX xX_____________NO. 1 BLACK (6)____ 7/
NO. 1 BLACK (49) Jy
Figure 39 Battery circuit.
96
(3) Battery ground circuit open. Turn on lights. Connect a heavy jumper wire between negative terminal of left battery and ground (fig. 39). If lights burn, ground circuit is open or master switch is defective. Check ground circuit and switches with test lamp. Clean and tighten terminals on ground end of cables.
(4) Battery to shunt circuit open. If lights do not burn, run a heavy jumper wire from positive terminal of left- or right-hand battery to lower terminal of shunt in apparatus box (fig. 39). If lights burn, circuit is open on both left- and right-hand batteries. Check with test lamp or jumper from terminal to terminal and correct condition on both left- and right-hand circuits.
(5) Battery connecting cable loose or broken. If lights still do not burn, test cables that connect batteries, using a jumper. Replace cable if broken or defective.
(6) Battery discharged—one or more cells dead. Check each cell of each battery with hydrometer and voltmeter. If battery is low, recharge with outside source or engine generators, or replace, as tactical situation permits. If one or more cells are dead, replace units containing defective cells.
b. Batteries Do Not Stay Charged. (1) Excessive use of electrical equipment. Keep one or both engines running at 1,500 revolutions per minute while using electrical equipment in accordance with the load.
(2) Generator charging rate inadequate. Check and service charging circuit (par. 46).
(3) Batteries not capable of holding a charge. Test each battery with hydrometer and high discharge test. Replace substandard battery units. Check for batteries connected with reversed polarity.
45. Lighting System
a. No Lights. (1) Circuit breaker open. Reset lighting system circuit breaker by pressing button on instrument panel (fig. 6).
Caution: If circuit breaker will not stay closed, do not hold in closed position. Check lighting circuit for short or ground.
(2) No current in feed circuit. Use test lamp or voltmeter to check power feed to lighting switch BATTERY terminal. If there is no current to this point, check back through the feed circuit (figs 40, 41 or 42) until the “short” or “open” is located, and repair or replace wiring or conduit as required.
(3) Defective lighting switch. If power feed-to-switch is satisfactory, use a jumper wire to connect BATTERY terminal with other terminals. If lights burn, replace lighting switch.
b. All Lights Dim. (1) Battery voltage low. Check battery condition with hydrometer and voltmeter. Recharge or replace batteries as required.
97
98
|T f INSTRUMENT PANEL—x U-< -- MAIN LIGHTING SWITCH
4K\ T [®016^P"AI1 '----FRONT OF VEH.CLE
w<'« IpootH
WCoroond w,« NO14 "ED 2"NAL18 (l6)
n 12 RED BL. TR. (15) APPARATUS BOX-v
I N°’ U RED 2// NAT' TR I2’) /~C°J ™ % apparatus box-. barter relays R|GHT TA|LL|GHT J
W/>V\\ /7O\I Sw & ss<75) I 7/
( NO 14 BL (25) NO. 14 NAT. 2/Z RED TR. (23) / ~L°J
I A—SIREN |PvJ\V_ NO12 RED BL-TR-(15) £’( P/r%E U
- i7x\hrNO-14 maroon (25) 7 (ftPIra "—FRONT OF VEHICLE
i /'/y© y) * ~NO-14 RED 2// slack TR-122) . r’W/^ IIW Lo)S
r LIGHTING SWITCH | '' k// R. H. REGULATOR_J
LIGHTSWITCH CIRCUIT BREAKER W -Jx L— INSTRUMENT PANEL CIRCUITBREAKER 1 \]\\\ Igl
liohi owiicHy (30 amps.)—||^wlrr—S. \ (I (6) IlW | JK-^NO. 10 RED-BLACK TR. (10)
f=r° \ LEFT STOP \| U ) \ V^jr-NO. 14 BL. (75) Z
v 'KER'r^//^ UJ NO. 14 NAT., GREEN TR. C ZOl^ - 1 S
•’ । tZ=c 2®w/ / I
uTERMINAL^^_ R. H. GENERATOR hl
NO. 6 BLACK (2)-•// • Gl® I 14 ll\\
NO. 6 BLACK—► // W i 1 £ // \\
(4) I NO. 14, GREEN TR.-U J/ L olffiTTmTl, K //
1 111 // // 0”l' I/
CIRCUIT BREAKER [8 ■ M । /WC
BATTERY TERMINALy^^^AMH MU | ----NO. 6 BLACK (202)-
ARMATURE TERMINAlI^T^X % //// W^-NO. 16 GREEN (9) ( // ARMATURE TERMINAL (2)?
L. H. REGULATOR ]—Ji FIELD TERMINAL (1) , /
rioi II n/r-IT nO. 16 RED (8) . = । „ Flh------Fl //
■^1liTK T ' -xi receptacle) I --- I 1/ \| //
// I V FIELD ____- -AMMETER SHUNT fen /
T NO- 16 GREEN (9) V< -fflLH X- TERMINAL = rr/
>Qal 3(8(Vny J (C RECEPTACLE) , --;■■ ■■ , I W
5^// h„ N0-4 RED '4> I VS
“.oil n 1 it 1 —i——um
°D " 1 I NO. 16 RED (8)-J \
2 Hi os // // I / I
O g1 IL NO. 16 RED (8)_____L------V18I7-JJ—A-------' L H- GENERATOR^
2 V A\
NO. 16 GREEN (9) Zc NO. 14 NAT,, 2// GREEN TR. (11
NO. 6 BLACK (2)
Figure 1^3. Charging circuit.
102
(3) Defective ammeter. Connect precision ammeter in circuit. Replace vehicle ammeter if defective.
(4) High resistance in charging circuit. Check entire charging circuit (fig. 43) for loose or corroded connections using voltmeter, and correct any conditions causing high resistance. High resistance makes regulator operate as if battery were fully charged.
(5) Inoperative regulator. Check regulator action by substituting a regulator known to be satisfactory. If charging circuit is satisfactory, replace defective regulator.
(6) Inoperative generator. If replacement of regulator does not remedy condition, replace generator.
47. Electrical Instruments and Equipment
a. Temperature Gage Does Not Register. (1) Open feed circuit. Connect jumper wire from gage unit in instrument panel back to ignition switch (fig. 45). If gage operates, replace feed wire.
(2) Defective gage unit. If gage does not operate when jumper wire is connected, gage unit is defective. Replace gage unit.
b. Temperature Gage Reads High at All Times. (1) Defective engine unit. Disconnect lead at engine unit. If gage drops to low side, engine unit is defective. Replace engine unit.
(2) Circuit to engine unit grounded. If gage remains high with wire disconnected, use test lamp to determine place where line between engine unit and gage unit (fig. 45) is grounded.
(3) Defective gage unit. If no ground is found in circuit, replace gage unit on instrument panel.
c. Temperature Gage Reads Low at All Times. (1) Circuit to engine unit open. Connect test light to engine unit terminal and to ground. If light does not burn, check back through circuit for loose or broken connection.
(2) Defective engine unit. If lamp lights, disconnect lead at engine unit and watch gage unit. If gage unit has high reading, engine unit is defective. Replace engine unit.
(3) Defective gage unit. If gage unit does not show high reading under the above circumstances, it is defective. Replace gage unit.
d. Warning Signals Do Not Light When Ignition Is Turned On.
(1) Burned-out lamp. If only one signal fails to light, the fault is probably in the lamp on the instrument panel. Check by replacing with new lamp (par. 93).
(2) Defective engine or transmission unit. If only one signal fails to light, and the lamp is not at fault, disconnect wire to affected switch on engine or transmission and ground it. If lamp lights, replace switch.
(3) Open circuit. If lamp fails to light, use test lamp to check
103
VN°-16 GREEN'RED TRACERy ||
HI^C (234-235) ii \ ,—ft
R. H, IGNITION f H. TRANS. OIL PRESSURE SIGNAL EH {(
SWITCH-rMU ©O/lrJ I pa (234-34)
'y r\C~/ zMrV N°' 14 BLUE (273) HP (235-35) M U34 34)
L. H. IGNITION MM R. H. ENGINE OIL PRESSURE AND HEAT ^^>8(234-235) W
SWITCH I FRONT OF VEHICLE g g
z^M4^YRHENG'NETEMPERATUREGAGE W r.h.tWature g MvM
//" x\ —n-NO. 16 GREEN RED TR. (234-235) H SIGNAL SWITCH .>
I ( frb i I 3® R- H. OIL SIGNAL
11 12) ]\ -NO. 14 BLUE (227) J fz8 (234-235) SWITCH
NO, 16 BROWN (34-35) A g||
tI I*" y
QJ W NO. 16 GREEN, RED TRACER (234-235)
z^r-NO. 14 NAT. RED TR. (27) I B ,34’35)^\
L. H. ENGINE TEMPERATURE GAGE M ^8 I. H. OIL SIGNAL SWITCH
( -*7) M L. H. TEMPERATURE Fa
NO 16 BROWN -rv-^^Z '''-'J I-H. ENGINE OIL PRESSURE AND HEAT & SIGNAL SWITCH W ((
l34’351 ^o^Pffs,GNAL ft O I
W prjL^rNO-14 NAT 'RED TRACER (73> ^y>B (34-35) 'G ^7 O®[ . L H' TRANSMISSION OIL PRESSURE fUl (35-235) fl (34-234)
V SIGNAL CT
/ (34'35) co y S
INSTRUMENT PANEL-' W NO. |6 BROWN (34-35) M / H .
' ■ ■ ionise [/ w
/^-NO. 16 GREEN, RED TRACER—* M
NO. 16 GREEN, RED TRACER (234-235)
Figure 44- Engine ail pressure and heat signal circuit.
104
" NO. 16 G_REEN, BLACK TRACER (272) _ NO. 16 GREEN, BLACK TRACER (272) -I g
® NO. 14 YELLOW (233) 3 j'gXA
1 || NO. 14 YELLOW (233) ,-gAI W
) fl /F I~
NO. 16 GREEN, BLACK TR. (272) O (233-33) M (272-72)
R. H. TRANSMISSION SIGNAL ---FRONT OF VEHICLE J®. JX/jl
A’233>-^/XD(272) W
noi4yellow(233) > 0 8
NO. 14 BLUE (273) Q fl
R. H. TEMPERATURE GAGE R' H' J^P|E|I^JUKE O
ESS OAUt UNIT Knag '---_
NO. 14 BLUE (227) ® R- TRANSMISSION
NO. 16 RED BLACK TRACER (72) [()) A (233)J~>D (272) OIL SIGNAL SWITCH
R. H. IGNITION SWITCH W7
L. H. IGNITION SWITCH NO. ]4 YELLOW (33-233) || _
-—•-- ■ NO. 14 NAT. RED TRACER (27) B IgsS ^NO. 16 GREEN, BLACK TRACER (272^
O D'72’ NO 14 YELLOW (233)
ll\\. J) . L. H. TEMPERATURE GAGE M g|| inu. 14 tclluw
H L H-VEMPERATURE /z^vx—1..
AiArrr NO. 14 WHITE (33) fl GAGE UNIT W // \\ -=
10^01___________ U HAT. R<0 W3) fl liht I W
Jl/ A (331’C'>D (72)
01^4 Y°Wtt---L H' TRANS- SIGNAL J! ---------
I „ m Z^V// *-NO. 16 GREEN, BLACK TRACER (72-272)
xy. /ZZ-X-^>^-NO. 16 RED. BLACK TRACER (721 Egf /
f f33)A|||[ c (72) S s
~_NO. 16 RED, BLACK TRACER (72) ^NO. 14JELLOW (33-233) -
NO. 14 YELLOW (33-233) W
Figure 1,5. Engine temperature gage and transmission signal circuit.
105
back through affected circuit (fig. 44 or 45), and correct condition causing open circuit.
e. Warning Signals Light. (1) Low oil pressure or high temperature. Ordinarily, lighted signals means high engine temperature, or low oil pressure in engine or transmission. If, however, a check of gages and oil levels indicates nothing abnormal, check the electrical warning circuit as follows:
(2) Defective engine or transmission switch. Disconnect lead at switch. If light goes out, replace switch.
(3) Ground in circuit. Check back through affected circuit (fig. 44 or 45), using test lamp or voltmeter to locate and correct grounded condition.
f. Siren Fails to Operate. (1) Circuitbreaker open. Push reset button on instrument panel.
(2) Siren switch defective. Test switch with jumper wire. If siren operates, replace switch.
(3) Open circuit to siren. Check back through siren circuit (fig. 42) with test lamp or voltmeter. Locate and correct “open” or “short” ondition.
(4) Defective siren. If circuit checks satisfactorily, siren is defective. Replace siren (par. 98).
g. Siren Operates Weakly. (1) Battery voltage low. Check with voltmeter. Recharge or replace affected battery units.
(2) High resistance in siren circuit. Check back through siren circuit (fig. 42) with voltmeter. Locate and correct high resistance condition.
(3) Defective siren. If circuit checks satisfactorily, siren is defective. Replace the siren.
h. Fuel Pumps (One or Both) Fail To Operate. (1) Circuit breaker open. Push circuit breaker reset button on fuel switch bracket.
Eote. Open circuit breaker would make both pumps inoperative.
(2) Defective switch. Test fuel-pump switch, using jumper wire. If pump operates with jumper in place, replace switch.
(3) Open circuit to pump. Check entire pump-feed circuit (fig. 46) from ignition switches to connection at pump support. Locate and correct cause of open circuit.
(4) Defective lead in fuel tank. If circuit checks to terminal on pump support, remove support assembly from fuel tank (par. Ill) and check lead to pump. Replace if defective. One ignition switch must be on when testing pump circuit.
(5) Defective pump. If lead to pump checks satisfactorily, pump is defective. Replace the pump (par. Ill).
i. Ventilator Fails To Operate. (1) Circuit breaker open. Push circuit breaker reset button on left front of ventilator assembly.
106
(2 ) Open feed circuit. Check feed circuit with test lamp at connector. If there is no current, check back through circuit (fig. 47) until open circuit is located and corrected.
(3 ) Defective ventilator. If feed circuit checks, ventilator has internal short, broken switch, or other defect. Replace complete ventilator assembly (par. 103).
48. Radio Interference Suppression
a. Preliminary Instructions. When checking radio interference, test the vehicle in a location free from high-tension lines, other vehicles, machinery, and electrical equipment which could be a source of interference. Stop engine and turn off all vehicle electrical equipment. Turn on radio and check noise level. Listen carefully to type of noise present under these conditions. This registering of noise sounds is done so that when vehicle equipment is checked, the presence of a new noise or interference can be immediately detected. Checking noise level is also done so that noises already present will not be attributed to lack of vehicle suppression. If noise level with all vehicle equipment shut off is too high, due to atmospheric conditions or other outside causes, delay further checking if tactical situation permits until such time as moderate noise levels prevail. Disconnect the radio terminal box capacitor (terminal end) (fig. 87). If radio interference does not increase, replace capacitor. If interference increases, as it should, leave terminal box capacitor disconnected for the remainder of the tests, or until any defective equipment has been located, replaced, and tested. Examine all shielded conduits and cables to make sure couplings are tight and conduits and cables are clamped or bonded to hull at least every 2 feet.
b. Noise Caused by Ignition System of Vehicle Engines. Radio noise caused by the engines of the vehicle can be determined by running first one engine and then the other engine. It is very unlikely that noise wrill be present in both engines at the same time. However, if such is the case, the remedies given below will apply for both engines.
(1) Loose or damaged conduits or wiring. Examine conduit of ignition system and see that all coupling nuts and terminal connections are tight and that conduit is not broken or crushed (fig. 89). Replace any damaged conduit or wires.
(2) Loose bonding clips or engine grounding strap. Tighten all bonding (holding) clips and tighten engine ground strap (fig. 88).
Note. If remedies given in this subparagraph do not correct the trouble, and the trouble is believed due to ignition faults, refer to higher authority.
a. Noise Caused by Generator. (1) Faulty generator regulator. If radio operator reports the radio interference as a clicking sound, the trouble is probably due to a faulty generator regulator. Tighten bolts holding regulator unit to mounting strap, tighten bonding strap be-
107
NO. 14 ORANGE (78)-^ z— NO. 14 RED, GREEN TR. (76)
=-T?“~ ”-EMERGENCY ll igj f
NO. 14 \ A (76) zjav, IGNITION Hf / T5T
GRAY (77^ B(77) W SWITCH BOX I / I TERM,NAL
IRCUIT BREAKER C rf®) n *----NO. 14 ORANGE (78)-/--J
WITCH ISI (76)
Z HE(77) Oco
8U===x, Igg F (78) TT
d (76)/ XL. '© 01 XVH (78)
e(77)m Ln A Il
F / FT W—IT-NO. 14 RED, GREEN TRACER (76)
/ /L~Lk 1 iHL k1„ -fuel PUMP
IGNITION SWITCHES_/ ( (5) ] rMMk II NO. 14 ORANGE (78) SUPPORT ASSEMBLY
(EITHER SWITCH V\Ey
CLOSES FEED CIRCUIT) MZC/ VU 0)rTERMINAL BLOCKS j
Jl
(( © )) L A
-<-FRONT OF VEHICLE \k 7/ J
V^©ocob
NO. 14 GRAY (77)-,_► \pM°°-
"on HrNO-14 GRAY (77n 1 /
IERM,NAl
INSTRUMENT PANEL I (77) Z
Figure A6. Fuel pump feed circuit.
108
I-----J ^-NO. 16 RED (38) — NO. 14 BLACK, RED TR. (59)
Ay? Ax^NO. 14 NAT. (59)/ y-NO. 14 NAT. (59-71)
AS“SS 1\ / f VENTILATOR A A INSTRUMENT PANEL
TWA' X A (59) I________________1 C (59-71) 4/A O U
NO. 14 BLACK, RED TR. (59)K JF~ / O
EMERGENCY IGNITION 1) 0 H [7 777//# A^IIhL -It M „n.„,T,,e
SWITCH BOX I A X211) U [J [J IJ[// /A \ NO 1 STARTER
x _k I Z2J A \--------F \\ NO-12 RED- / /—relays
NO. 16 RED (38) —• AJl^JKfL^A-TTT^ //"^F-------n—BLACK TR. (211) / /
A C (59-71) W /7 /WtH /~r i- ■'— --F74U^
CIRCUITBREAKER *• —■= hsi. Z/W || U © Illi { Lt) //
^-^^^^==^^(59-71) NO. 14 NAT. (59-71) ||
NO. 14 BL. RED TR. (71)—|\ \ NO. 12 RED, BLACK TR. (211)
DRIVER'S Y PLUG FOR WINDSHIELD WIPER W Ol iSa
DOME LIGHT \ 1 S
NO. 14 NAT. (71)—J \\^y/// 1/
JI \
CIRCUIT BREAKERS-^J \ NO. 10 RED^
(---- / W \ BLACK TR.
/ '-TO BATTERY V-SHUNT
II G=/--- 11/ R H REGULATOR
X- -jy CIRCUIT BREAKER
NO. 10 RED, BLACK TR. (10)
Figure 47. Dome light, ventilator, and windshield wiper circuit.
752022 0—47-----8
109
tween regulator mounting strap and apparatus box (fig. 90). If noise continues, replace regulator (par. 82).
Note. If remedies given in this subparagraph do not correct the trouble, refer to higher authority.
(2) Generator system noise. If radio'interference is caused by the generator system, tighten all bonding clips, coupling nuts, and ground straps (fig. 88). Examine conduit and if it is crushed or cut, or in any way damaged, replace the conduit and/or wires (par. 106). Tighten conduit fittings in junction and apparatus boxes. If noise continues, replace first one, and if necessary both, of the condensers which are found on the brush-holding plate of the generator. Replace them in the same position as the original ones were installed. If noise still continues, refer to higher authority.
d. Noisy Gun Mount Elevating Electrical System. If radio noise is believed due to faults within the howitzer-mount elevating electrical system, it can be determined by elevating weapon with vehicle engines stopped. If radio interference is caused when weapon is elevated, the fault lies within the following:
(1)2^aulty conduits, wiring, or bonding. Tighten all coupling nuts and bonding clips. Replace all defective conduit and/or wiring. If either strap or cable is damaged, refer to higher authority. Tighten all conduit fittings in junction and control boxes and tighten switches and junction blocks in switch boxes. If noise continues and trouble is not remedied, refer to step (2) below.
(2) Faulty motor. If cause of radio interference is not traceable to (1) above, it is probably due to a faulty motor. In either case, refer to higher authority.
e. Noise Caused by Miscellaneous Systems. Noise may be caused by loose or damaged conduits or wires of the lighting systems, various instruments including their respective sending units such as fuel tank gages, engine temperature gage and signals, oil-pressure gage and signals, and speedometer and tachometer. Various instruments on the instrument panel and in control boxes may become loose. Battery terminals and ground cable of the batteries may work loose or become corroded or otherwise damaged. The lights of the vehicle and their switches, as well as the capacitors in windshield wipers, are also sources of radio noise.
f. Location and Remedy of Miscellaneous Radio Noise. The same general rule for maintenance of various systems, instruments, and devices must be followed as given previously concerning correction of radio interference. A process of elimination can be applied to location of trouble within any system.
g. Radio Interference Not Traceable to Any Electrical System. If radio interference persists in spite of remedies set forth in b to and including f above, the trouble is probably due to defective radio
no
apparatus or to faults within the structure of the vehicle. Refer to higher authority.
49. Cooling System
a. Loss of Coolant. Inspect all hose connections for leaks and tighten where leaks are evident. If tightening does not stop leakage, replace hoses. Inspect thermostat housing and radiator outlet elbow for leakage at gasket and replace gasket if required. Look for leakage at radiator cap gasket when engines are at maximum operating temperature and replace complete cap if leakage occurs under pressure. Look for leaks at transmission-to-engine water pipes. Tighten connections or replace pipes and fittings as required. Inspect water pump for leaky packings, and notify higher authority if this condition is found. Look carefully for leaks at radiator core and tanks, and repair or replace radiator as required. Check for leakage at cylinder heads and blocks. Tighten head screws to 65 to 70 foot-pounds or replace gasket as required to correct leakage. If head or block is cracked, replace entire engine.
b. Engine Overheats. See paragraph 42e.
c. No Water Circulation. Inspect the cooling system water level and refill to bring coolant up to proper level. After refilling, check complete system to determine cause for loss of coolant. Inspect the drive belts and adjust to obtain %- to %-inch slack measured midway between water pump and generator pulley (fig. 50). Replace badly worn or damaged belts. Caution: Belts must be replaced in matched sets of three except in an emergency. If the latter is the case, the belts should be removed and replaced with a set of matched belts as soon as the conditions permit. If, after checking the above conditions, there is still no circulation, remove the thermostate housing and check the thermostat. If thermostat is correct, clean cooling system thoroughly (par. 115) to restore circulation. If coolant does not circulate after system has been cleaned, remove water pump and inspect for sheared impeller. If impeller is sheared, notify higher authority.
50. Fuel System
a. Lack of Fuel at Carburetor. Check position of fuel pump switches and turn to “ON” position. Make certain that fuel tank is not empty and replenish fuel supply if necessary. Check condition of carburetor strainer screen at carburetor and also check auxiliary fuel filter at carburetor inlet fitting. Clean if necessary. Inspect fuel lines for clogged or leaky condition and clean or replace as necessary. Remove fuel pump support and clean strainer screen, and screen on pump and reinstall (par. 111). Check fuel pump to find out if pump motor operates by listening for pump motor with fuel switch turned on and vehicle engine not running. If inoperative,
111
replace pump or notify higher authority. Inspect fuel valve, and check valve at tank and free up or replace if inoperative. Check fuel valve cable to make certain cable is not broken, disconnected, or loose and out of adjustment. Reconnect, readjust, or replace as necessary.
b. Carburetor Not Operating Properly. Check choke thermostat housing adjustment and reset to indicator mark, if necessary (fig. 93). Check to be sure choke is free from all sticking or binding. If choke cannot be freed by moving lever on end of shaft (fig. 94), notify higher authority. Check carburetor adjustments (par. 110) to make sure fault is not in the adjustments. If above measures do not correct the difficulties, replace carburetor or notify higher authority.
51. Transmission
a. Lubricant Leaks. Check transmission for oil leaks at the drain plug, oil pan, and side cover. Tighten drain plug or cover attaching screws to stop leak. If leak will not stop, replace gaskets or drain plug. If fluid coupling is found to be leaking, do not attempt to repair. Notify higher authority.
b. Transmission Fails to Transmit Power. Check transmission oil level and fill to level mark on gage (par. 33). If oil level was low, check transmission thoroughly for oil leaks. If transmission still does not function, adjust manual control linkage (par. 121). As a final step, check the front band adjustment (par. 122) and readjust as required.
Note. Rear band has automatic adjustment and does not require attention.
c. Transmission Shift Speeds Abnormal. If all shifts occur at excessively high engine speeds, check vacuum line between transmission and intake manifold for leaks at fittings or cracks in line. Repair or replace as necessary. If engine speeds up in first and third while being driven forward, the front band is out of adjustment. Readjust front band (par. 122). If engine speeds up in first and second, rear band is out of adjustment. Rear band adjustment is automatic; if band is slipping, notify higher authority. When all shifts above second occur at excessive engine speeds, the manual control linkage is improperly adjusted. Readjust manual control linkage (par. 121). 6
d. Vehicle Creeps. Check engines to make sure idling speed is down to 450 revolutions per minute and that throttle linkage does not bind. Eliminate bind in throttle linkage and replace missing or weak throttle return springs.
52. Propeller Shafts
a. Vibration at Universal Joints. Replace all propeller shaft joints having worn needle bearings. Check shafts for run-out and replace all affected shafts.
112
Z>. Heavy Thumps on Rough Terrain. Check transfer unit universal joint slip yokes to make sure yokes are free on shaft splines. Replace frozen slip joints,
c. Oil Leakage at Universal Joints. Check oil seals at universal joints and replace affected propeller shaft joints.
53. Transfer Unit
a. Transfer Unit Does Not Respond to Control Lever. Check shifter shaft extensions to determine if extensions are loose on shifter shafts. If loose, tighten and readjust control rods (par. 130). If extensions are not loose, check transfer unit control rods for adjustment and adjust if necessary (par. 130). If transfer unit will not shift properly after checking above operations, check the yokes on the shifter shafts. If yokes are loose on shifter shafts, replace transfer unit or notify higher authority.
b. Transfer Unit Overheats. Check transfer unit oil level and, if necessary, add oil to bring level up to full mark on gage. If oil is low, check unit to determine cause for loss of oil. If oil level is too high, drain or siphon until oil is at FULL mark on gage. Too high an oil level will cause excessive foaming which will cause overheating. If transfer unit continues to overheat, check the oil pump operation in the following manner: Open sliding door over transfer unit and remove one of the %-inch pipe plugs from top of case. Start engines, place transfer unit shift lever in NEUTRAL position, and transmission lever in DRIVE. If oil pump is operating properly, oil will flow out of the plug opening. If no oil flows from plug opening, notify higher authority.
c. Gears Clash When Shifting. If gears clash in cold weather, it may be that the transfer unit lubricants have not been warmed up sufficiently. Start engines and place transfer unit shift lever in NEUTRAL and transmission selector lever in DRIVE. Allow engines to run until the transfer unit warms up. Check for proper seasonal grade of lubricant. If gears clash due to improper use of the neutral pedal, review the driving instructions (par. 15). If gears continue to clash, check the transfer unit control linkage and adjust as necessary (par. 130). If gears clash after adjustments have been made, clash is likely to be due to the clutch synchronizers not operating properly. Notify higher authority.
54. Controlled Differential
a. Vehicle Hard to Steer or Stop. If vehicle is hard to steer or stop, check steering brake adjustment and adjust as necessary (par. 134Z>). If brake bands are highly glazed or worn, replace bands (par. 135).
b. Brakes Require Frequent Adjustment. If vehicle brakes require adjustments frequently, driver should observe driving instruc
113
tions (par. 15) to insure proper handling of vehicle. If brakes continue to require adjustments, check brake rims for roughened condition. If found to be rough or damaged, notify higher authority.
55. Tracks and Suspension
a. Suspension Wheel Tire Wear. If suspension wheel tires show excessive wear, check track blocks for bent guide or other damage which would have tendency to cut or wear tires. Repair or replace damaged blocks or tracks as necessary (par. 144).
Z>. Thrown Tracks. If track was thrown, check complete suspension to determine cause. Improper track tension, damaged compensating wheels, foreign matter between track and wheels, or a broken front torsion bar are the most likely causes for the track to be thrown. Adjust track tension (par. 143), replace damaged compensating wheels (par. 145), clean out foreign matter, or replace broken torsion bar (par. 149).
c. Inoperative Track Supporting Roller. Check roller to make certain no foreign matter is caught between track roller and track, or between track roller and support. If roller is free of foreign matter, check bearing adjustment. If bearing has seized, replace roller assembly (par. 151).
d. Inoperative Compensating Wheel. Check compensating wheel to make certain no foreign matter is caught between wheel and track, or compensating wheel support. If wheel is free of foreign matter, check wheel bearing adjustment. If bearing has seized, replace bearings (par. 145).
Section XVI. ENGINE DESCRIPTION AND MAINTENANCE IN VEHICLE
56. Engine Description and Data
a. Description. (1) This vehicle is powered with two 90°, V-type, 8-cylinder, 4-cycle, liquid-cooled engines (fig. 48), mounted side-by-side in the engine compartment in the center of the hull. The engine cylinder blocks and crankcase, made in one casting of grey iron, sup-poi t the crankshaft and camshaft, and enclose the reciprocating parts. Cylinder heads are of cast iron also. The cylinders are arranged in two banks of four each, located 90° apart. Opposite connecting rod assemblies operate side-by-side from the same crankshaft journal.
(2) The distributor, ignition coil and wiring, carburetor, intake and exhaust manifolds, and cylinder heads are accessible through the engine compartment hinged air outlet grille. The starter and the engine oil pan are accessible through an inspection opening with removable cover in the hull floor. The belts, water pump, generator
114
and oil filters are accessible after removing access plates at rear of engine compartment.
(3) The generator end of these engines is designated the front end, even though it faces the rear of the vehicle, and the flywheel end is designated the rear end. The right and left sides of each engine (and transmission) are determined by standing at the transmission and looking toward the generator end. Right- and left-hand engines in the vehicle, however, are designated according to their relation to a man sitting in the driver’s seat. The engine on the right of the hull is the right-hand engine. Engine supports, cushions, and attaching brackets and bolts are considered with reference to their position in the hull rather than their relation to the engines. Thus, the support under the transmission is designated as the engine front support, although it attaches to the rear of the engine, and the two supports at the generator end are the engine rear supports.
b. Data.
Bore and stroke-------------------------3y2 x 4^ in.
Compression ratio_______________________ 7.06 to 1.
Cylinder numbering______________________Refer to fig. 74.
Engine make_____________________________Cadillac.
Engine supports, number of______________4.
LIFTING EYE
ENERATOR
SOLENOID
CRANKING MOTOR
BY-PASS HOSE FOR COOLANT
CRANKCASE VENTILATING
AIR CLEANER
ST MANIFOLD CROSS-OVER
PUMP
ENGINE SUPPORT
REAR CUSHIONS
SERIAL NUMBER RA PD 331806
IGNITION COIL
Figure 48. Engine, three-quarter front view.
115
4 CARBURETOR
b. Data (Continued).
Firing order---------------------------- 1, 8,7, 3,6, 5,4,2
„ (fig-74).
Horsepower, net installed---------------110 @ 3,400 rpm.
Piston displacement (each)______________346 cu. in.
Valve arrangement_______________________ L-head.
Weight of engine and transmission assem- 1,166 lb.
bly.
57. Engine Tune-Up
The operations required for a complete engine tune-up are listed below.
a. Clean and adjust or replace spark plugs (par. 75).
b. Clean and adjust, or replace contact points (par. 70).
c. Check ignition timing (par. 73).
d. Clean carburetor auxiliary filters (par. 110).
e. Service carburetor air cleaners (par. 109).
/. Adjust carburetors (par. 110).
58. Operations Performed With Engines in Vehicle
The following operations can be performed without removing the engines from the vehicle (fig. 49) :
a. Adjust or replace belts (par. 59).
b. Adjust carburetor (par. 110).
c. Replace carburetor (par. 110).
d. Service carburetor auxiliary filter (par. 110).
e. Service cooling system (par. 115).
/. Replace cylinder head gaskets (par. 60).
g. Replace distributor (par. 70).
h. Adjust or replace distributor contact points (par. 70).
i. Replace generator (par. 81).
j. Replace hose connections (par. 116).
k. Replace ignition coil (par. 71).
I. Replace ignition condenser (par. 72).
tn. Adjust ignition timing (par. 73).
n. Replace ignition wiring (par. 74).
o. Replace manifold gaskets (par. 65).
p. Replace manifolds (par. 65).
q. Service or replace oil filter (par. 62).
r. Replace oil filter connections (par. 62).
s. Replace oil pan (par. 63).
t. Replace oil pump strainer (par. 64).
u. Replace signal sending units (par. 97).
v. Adjust or replace spark plugs (par. 75).
w. Replace starter (par. 77).
x. Replace water pump (par. 109).
116
AIR INLET RADIATOR R. H. GASOLINE .ENGINE COMPARTMENT
GRILLE A FILLER COVERS TANK FILLER COVER/ R. H. AIR OUTLET DOOI
RADIATOR AIR L. H. GASOLINE ENGINE / ENGINE COMPARTMENT
INLET ASSEMBLY TANK FILLER COMPARTMENT L. H. AIR OUTLET
COVER REAR ACCESS PLATE DOOR
Figure 49. Engine compartment covers.
59. Belt Adjustment and Replacement
a. Description. A triple-grooved pulley, mounted on the front of the crankshaft carries three V-belts which drive the water pump and generator (fig. 50). A bracket on the engine front cover provides for mounting the generator, and a movable cradle assembly permits belt adjustment.
b. Belt Tension. The tension of the three water pump and generator belts should be adjusted if belts can be deflected more than % inch as measured midway between pulleys (fig. 50).
c. Belt Adjustment. (1) Open master battery switch. Refer to paragraph 10.
(2) Open engine compartment door. Turn latch at side of doors to unlocked position and raise doors. A folding prop is hinged to front edge of door and may be used to hold door in open position.
(3) Remove generator and oil filter access plate. Remove four bolts attaching generator and oil filter access plate to cover at rear of engine compartment and remove plate (fig. 59).
117
RA PD 3319381
(4) Adjust belts. Loosen adjusting nut and pivot nut for generator cradle. Insert large screwdriver or utility bar between front cover and cradle, and raise generator and cradle until slack in belts midway betwen water pump pulley and generator pulley is %- to 34-inch. Tb’s can be measured using a straightedge and pressing firmly on belts midway between pulleys with a scale (fig. 50).
(5) Install generator and oil filter access plate. Position access plate on cover at rear of engine compartment and install four attaching screws (fig. 59).
--- GENERATOR
-------- SCALE
------- 5/8-3/4"
ADJUSTING NUT
“ WATER PUMP
PULLEY
RA PD 331805
Figure 50. Belt tension.
(6) Close engine compartment. Close engine compartment doors and turn latch handles to locked position.
d. Belt Replacement. (1) Open engine compartment. Open engine compartment air outlet doors. Remove access plate at rear of engine compartment. See c above.
(2) Remove belts. Loosen generator cradle lock nut and pivot nut and allow generator to drop to its lowest position. Disconnect generator wires DRAIN PLUG
Figure 53. Removing oil filter cartridge.
(2) Remove generator and oil filter access plate. Refer to para-
graph 59(? (3).
(3) Remove filter element. Remove hex screw from top of oil filter cover and remove cover and gasket. Discard the gasket. Remove oil filter element by lifting out of filter (fig. 53). If filter element is tight, be careful not to nick the gasket surface on the filter body in prying the element out.
Caution: Be sure no oil is allowed to splash on belts in this operation.
(4) Clean oil filter. Remove drain plug from bottom of filter and allow old oil to drain. Wash inside of filter with cleaning solvent, wipe dry, and reinstall drain plug. Clean any spilled oil from filter body and hull floor.
(5) Install new element. Install new element in filter body. Place new gasket in cover and install cover and tighten screw to 18 to 22 foot-pounds torque.
Note. Be sure cover is seated squarely on body before tightening screw.
(6) Inspect installation. Run engine for several minutes to allow filter to fill with oil. Inspect for oil leaks. Check engine oil level and add oil if necessary.
(7) Install generator and oil filter access plate. Refer to paragraph 59c (5).
(8) Close engine compartment. Close engine compartment doors and turn handles to locked position.
c. Removal. (1) Open engine compartment. Open engine compartment hinged doors.
(2) Remove generator and oil filter access plate. Refer to paragraph 59c (3).
(3) Disconnect oil pipes. Place rags or container under oil filter to prevent oil running over hull floor. Disconnect inlet pipe at top of filter by unscrewing flared tube nut from elbow. Disconnect outlet pipe at bottom of filter by unscrewing flared tube nut from elbow.
Caution: Be sure no oil is allowed to splash on belts in this operation.
(4) Remove filter. Remove two nuts and bolts from clamp straps and lift out filter assembly (fig. 54).
(5) Remove oil pipes from engines. Disconnect inlet pipe from fitting connected to main oil header at front of cylinder block. Disconnect outlet pipe from fitting on engine front cover.
(6) Remove oil filter mounting bracket. Remove three nuts and washers holding mounting bracket to front of cylinder block. Remove the bracket.
(7) Install mounting bracket. Position mounting bracket over studs on front of cylinder block and install three nuts and lock washers.
123
(8) Connect oil pipes to cylinder block. Connect outlet pipe to fitting on engine front cover and inlet pipe to fitting at main oil header on front of cylinder block.
Note. Tighten pipes finger-tight.
(9) Install oil filter assembly. Position oil filter assembly in mounting bracket and install two clamp bolts, nuts, and lock washers. Connect outlet pipe to elbow on bottom of filter and inlet pipe to elbow on side of filter. Tighten all connections.
(10) Inspect installation. Run engine for several minutes to allow filter to fill with oil. Inspect for oil leaks. Check engine oil level and add oil if necessary.
(11) Install generator and oil filter access plate. Refer to paragraph 59c(5). P
(12) Close engine compartment. Close engine compartment door and turn latch handles to locked position.
124
MOUNTING L DRAIN OUTLET LINE INLET LINE
CLAMPS PLUG
Figure 54. Oil filter pipes.
63. Oil Pan and Gaskets
a. Removal. (1) Remove hull floor plate. Remove 18 screws from hull floor plate under engine compartment.
Caution: Support rear end of plate while removing last screws to prevent plate from dropping and causing personal injury.
Front end of plate is held up by hooks on cover. Slide plate toward rear of vehicle and lower to ground.
(2) Drain engine oil. Remove engine oil pan drain plug and allow oil to drain. Reinstall drain plug with gasket and tighten to 35 to 40 foot-pounds torque.
(3) Remove oil pan. Remove 25 oil pan screws. Lower rear end of oil pan and slide pan out through hull floor opening.
(4) Remove gaskets. Wash oil pan thoroughly with dry cleaning solvent. Remove all portions of oil pan gaskets from pan and bottom of cylinder block, and discard.
b. Installation. (1) Install oil pan gaskets. Coat gasket surface of cylinder block lightly with joint and thread compound (cement, type-II) to hold gaskets in position. Place gaskets on oil pan or on cylinder block.
(2) Install oil pan. Slide front end of oil pan carefully through hull floor opening. Position front end of pan on cylinder block and raise rear end of pan into position. While holding oil pan up against block with one hand, install two or three screws to prevent pan dropping down. Install balance of screws and tighten to 7 to 10 footpounds, using a torque wrench.
Figure 55. Removing oil pump strainer
752022 0—47-----9
125
■' OIL PAN BAFFLE—^
OIL STRAINER FLOAT ASSEMBLY
OIL PUMP-"""'
(3) Install hull center plate. Coat edges of floor plate with joint and thread compound (cement, type II) and place gasket on plate. Raise front edge of plate until hooks on plate rest on hull floor. Raise rear end of plate and line up screw holes with two drift punches. Install floor plate retaining screws.
(4) Install engine oil. Refer to lubrication order (par. 32).
64. Oil Pump Strainers
a. Removal. (1) Remove oil pan. Refer to paragraph 63a.
(2) Remove oil pump strainer. Remove cotter pin holding oil pump strainer and float assembly in oil pump body (fig. 55). Slide float and strainer assembly out of oil pump.
(3) Inspect strainer. Inspect float assembly to see that oil has not entered the float chamber. Shake assembly to detect presence of oil in float. If oil is found in float, unit should be replaced. If no oil is found in float, wash strainer thoroughly in dry cleaning solvent and blow dirt from strainer mesh.
d. Installation. (1) install oil pump strainer. Slide oil pump and strainer float assembly into oil pump body. Install cotter pin.
Note. Raise and lower strainer assembly several times to make sure it is free and that it will drop down of its own weight.
(2) Install oil pan. Refer to paragraph 636.
65. Intake and Exhaust Manifolds
a. Removal. (1) Open master battery switch. Refer to paragraph 10.
(2) Open engine compartment. Turn latches on engine compartment door to unlocked position and open door.
(3) Remove carburetor. Refer to paragraph 110a.
(4) Disconnect muffler assembly. Refer to paragraph 113Z>.
(5) Remove exhaust connection. Remove four screws holding exhaust connection to left and right exhaust manifold; lift up connections and discard gaskets.
(6) Remove ignition wire conduits. Disconnect conduits at spark plugs. Remove four nuts holding ignition wire conduit support brackets to manifolds. Lay brackets and wires to one side.
(7) Remove crankcase air cleaner. Remove two nuts and washers holding engine crankcase air cleaner to intake manifold. Loosen lower hose clamp and remove air cleaner assembly.
(8) Remove upper rear relay cross shaft. Remove clevis pin from lever on center of relay cross shaft. Disconnect throttle rods at cross shaft levers. Remove two nuts from relay cross shaft support (fig. 56) and slide cross shaft out of other support.
Note. Do not lose springs or washers from ends of cross shaft.
126
(9) Remove exhaust manifolds. Remove remaining nuts and clamps holding exhaust manifolds to cylinder block (fig. 57). Remove manifolds.
(10) Remove intake manifold. Bend back lock plates and remove four screws holding fan shaft universal joint to yoke at rear of intake manifold. Bend back lock plates and remove four screws holding fan shaft universal joint to yoke at front of intake manifold. Remove four intake manifold screws (fig. 57) and lift out manifold (fig. 58). Discard gaskets.
b. Installation. (1) Install gaskets. Clean gasket surfaces on crankcase and manifolds. Place two new intake and exhaust manifold gaskets on cylinder block.
(2) Install intake manifold. Lower intake manifold into position on cylinder block. Install four screws holding intake manifold to cylinder block. Using a torque wrench, tighten screws to 25 to 30 foot-pounds. Connect fan shaft universal joint at rear of manifold and install four screws and lock plates. Bend lock plates over head of screws. Connect fan shaft universal joint at front of manifold and install four screws and lock plates. Bend lock plate over head of screws.
(3) Install exhaust manifolds. Place both exhaust manifolds on gaskets and install intake and exhaust manifold clamps and clamp nuts. Using torque wrench, tighten nuts to 25 to 30 foot-pounds.
Note. Be sure to install spark plug wire conduit support brackets over the center studs on both sides, and to place carburetor retracting spring clip over left front stud and transmission filler pipe clip over right rear stud.
(4) Install exhaust connection. Install two new exhaust manifold connection gaskets on exhaust manifolds and install connection and four mounting screws. Apply antiseize compound (white lead base) to threads of these screws. Using torque wrench, tighten screws to 25 to 30 foot-pounds. After running engine a short time, recheck all manifold screws for proper torque tightness.
(5) Install crankcase air cleaner. Slide air cleaner hose over air cleaner front pipe on valve compartment cover. Position air cleaner mounting bracket over mounting studs and install nuts and washers. Tighten lower hose clamp on air cleaner pipe.
(6) Install carburetor. Refer to paragraph 110-GENERATORS y
^Bk- 'WBpafc • .....— -----
(-GASOLINE line y DISTRIBUTOR VENTILATING LINES
CLAMPS-J RA PD 331817
FAN DRIVE SHAFT YOKE KNURLED PACKING NUT
Figure 6^. Bulkhead extension attaching screws.
134
BULKHEAD EXTENSIONS COVER ATTACHING /- BULKHEAD EXTENSION SCREWS (LEFT SIDE)—/ SLIDING DOOR 1 //* / ’—•>
UNIVERSAL JOINT FAN SUPPORT ARMS
Figure 63. Loosening fan shaft packing nut.
BULKHEAD EXTENSION — BULKHEAD EXTENSION COVER
FRONT PANEL
HAIRPIN LOCK -t FULCRUM LEVER x TRANSMISSION y
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^CONNECTING LINK CLEVIS PIN A ^RANSFER UNIT
Figure 65. Disconnecting transmission control rod.
■ d I . generator
i F flv SZa /^Lz^SIk'
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IHmI BTERMiNAL
/TX’ Ufy X COVER
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' VFIELD LEAD '
bI 'iBV W (NO. 201-1)
L 1 ARMATURE LEAD (NO. 202-2)
RAPD 331266
Figure 66. Generator wires.
135
(16) Remove hull floor cover. Remove screws from hull floor cover.
Caution: Support rear end of cover while removing last screws to prevent cover from dropping down and causing injury.
Front of cover is held up by hooks on cover. Slide cover toward rear of vehicle and lower to ground.
(17) Disconnect hose connections. Loosen both clamps on each water outlet hose on cylinder head and push hose down on elbow until clear of radiator thermostat housing. Working under vehicle, disconnect lower hose at radiator end of water pump inlet tube.
(18) Disconnect transmission manual control rod. Working through bulkhead sliding door opening (fig. 64) or from under vehicle, remove hairpin lock and clevis pin that hold fulcrum lever to connecting link on rear relay (fig. 65).
V.SUNG (41-S-3831-3OO) * WS
GENERATOR CRADLE (GENERATOR REMOVED)'
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Figure 61. Removing engine.
136
(19) Disconnect engine f ront support. Working through bulkhead sliding door opening or from under vehicle, remove two cap screws, one on each side, for the engine front support bracket on transmission.
(20) Disconnect generator and starter conduits. Remove conduit from generator terminal by unsnapping wire clip from cover. Lift off cover. Unscrew conduit connection at bottom of wire shield box. Remove nuts and washers holding wires to terminals (fig. 66). Lift wires off terminals and pull wires out of box. Disconnect starter feed cable at battery terminal block on rear hull plate by removing cover, removing nut from stud, and lifting off cable.
(21) Remove generator. Refer to paragraph 81) Oil-soaked points usually do not require dressing. Clean points thoroughly, and then see that the source of oil leakage is determined and corrected.
(c) Pitted contact points will not cause ignition failure unless the pitting is severe. Do not replace points because of minor pits or projections. Remove, clean, and smooth up with a carborundum stone.
( for spark-plug specification. Check the condition of the ceramic insulator at end of each spark-plug conduit. Insulator must not be cracked and spring terminal at end of insulator must not be damaged or missing. Connect the correct conduits to each spark plug and tighten finger-tight, plus one-half turn with small wrench. Do not force these connections.
Section XIX. STARTING SYSTEM
76. Description and Data
a. Description. (1) There are two independent but identical starting systems, one for each engine. Each system includes a starter mounted on the engine, a solenoid for pinion engagement mounted on the starter housing, a starter relay mounted in the apparatus box on the front of the bulkhead, a feed circuit through the ignition switch, a starter button on the instrument panel, a safety circuit comprising a ground through the transmission warning signal circuit, and the necessary connecting wiring (fig. 37).
(2) To crank an engine, the ignition switch, master switch, and emergency ignition switch must be turned on and the starter button depressed. Current then flows through the two coils of the starter relay, and grounds through the transmission warning signal unit. Energizing the relay coils closes two circuits, one of which leads direct to the solenoid on the starter, while the other provides an independent ground circuit to function in case cranking action opens the transmission warning signa] switch. With current flowing through the solenoid, the starter pinion is drawn into engagement with the flywheel ring gear and the circuit for the heavy starting current is closed.
(3) If the starter button should be pressed while the engine is running, no current will flow through the starter relay because the oil
149
pressure built up in the rotating transmission will keep the warning signal switch open and thereby leave the relay with no ground connection. Whenever the engine stops and transmission oil pressure drops, the switch closes making the ground connection. The circuit can then be completed by pressing the starter button.
b. Data.
Starter:
Make------------------------------------Delco-Remy.
Model No--------------------------------1108568.
Type------------------------------------Four-pole, compound.
Voltage_________________________________24.
77. Starter
a. Removal. (1) Open master battery switch. Open master battery switches by pulling out on knob and turn about one-quarter turn to lock in open position.
Note. Remove starter only after tests (par. 42) indicate that this unit is at fault.
(2) Remove left hull floor plate. Remove screws from left hull floor plate. Support rear end of plate wdiile removing last screws to
150
Figure 75. Removing starter.
SOCKET ON UPPER IGNITION COIL STARTER ~\ MOUNTING SCREW FEED WIRE (212-12)
THROTTLE LOWER RELAY SOLENOID LEAD ^BATTERY FEED (274-74)
R.H. STARTER RELAY
RELAY SUPPORT ATTACHING SCREWS
Figure 76. Starter relay mounting.
prevent plate from dropping down and causing injury. Front of plate is held up by hooks. Slide plate toward rear of vehicle and lower to ground.
Note. The starters of both engines are accessible through the left hull floor opening.
(3) Disconnect battery feed cable. Remove nut from battery feed cable and lift cable off terminal. Disconnect wire from starter solenoid by removing nut and lifting off terminals.
(4) Remove starter. First remove upper mounting screw (fig. 75) which passes through flywheel bell housing; then remove bottom screw while supporting weight of starter with other hand. Remove starter through hull floor opening.
b. Installation. (1) Install starter. Reaching up through left hull opening, place starter in position in opening on flywheel housing so that dowel on housing fits into cut-out on starter flange. While holding motor in position with one hand, install lower mounting screw through flywheel bell housing and tighten screw. Install and tighten other screw.
(2) Connect wire and cable. Connect solenoid switch wire and also battery feed cable to starter, and install retaining nuts and washers.
(3) Install left hull floor plate. Place gasket in position on rear hull plate. Raise front end of plate and place hooks on plate over edge
151
APPARATUS BOX [
(COVER REMOVED) L. H. STARTER RELAY RA PD 331819
AMMETER ' SHUNT
of hull floor. Raise rear end of plate, aline screw holes with drift punch and install attaching screws and washers.
78. Starter Solenoid
a. Removal. Remove solenoid only after tests (par. 42) indicate that this unit is at fault. Remove starter (par. 77). Remove cotter pin and lever pin holding solenoid plunger link to starter clutch actuating lever. Remove four mounting bolts holding solenoid to starter. Remove bolt holding ground strap to starter. Remove lead wires. Lift solenoid off starter assembly.
b. Installation. Place solenoid in position on starter and install four bolts. Place clutch operating lever in position and lock with new cotter pin. Install lead wires on solenoid.
79. Starting Relay
a. Removal. Remove relay only after tests (par. 42) indicate that this unit is at fault. Open master battery switches. Remove eight screws and take off apparatus box cover. Disconnect five wires from relay terminal. Remove two hex nuts, washers, and screws, and remove relay assembly from mounting bracket in apparatus box (fig- 76).
b. Installation. Position relay on bracket in apparatus box and install hex nuts, washers, and screws, with ground wire inserted under inner screw. Reconnect five wires to relay according to diagram (fig. 37). Install apparatus box cover and secure in place with eight screws.
Section XX. GENERATOR AND CHARGING SYSTEM
80. Description and Data
a. Charging Circuit. Since there are two generators, one on each engine, there are two identical charging circuits, each connected so as to charge both batteries. Each charging circuit consists of a generator, a four-unit generator regulator, and the cables and conduits required to connect these units to the batteries (fig. 39).
b. Generators. Two generators are used, one mounted on each engine. Each generator is a 24-volt, 50-ampere, 4-brush, 4-pole, shuntwound type, with sealed, self-lubricated ball bearings supporting the armature. The generator is clamped in a mounting cradle and bracket, and driven from the crankshaft by three matched belts. The cradle is adjustable to provide correct bolt tension.
c. Generator Regulators. The two generator regulators are mounted in the apparatus box on the front of the bulkhead (fig. 77).
152
Each regulator consists of four units: a voltage regulator, a current regulator, a circuit breaker relay, and an actuating relay. These last two relays function together to perforin the same duty as a cut-out relay; namely, to open the circuit when generator voltage falls below battery voltage, and to close the circuit when generator voltage is sufficient to charge the battery.
d. Data.
Generator:
Model No----------------------------------- DR-1117309.
Output, cold-------------------------------48 to 50 amp.
Rotation, drive-end view------------------ Counterclockwise.
Winding------------------------------------ 4-pole, shunt.
Generator regulator:
Model No-----------------------------------DR-1118501.
Type---------------------------------------4-unit, 24-volt.
81. Generators
a. Removal. (1) Test generator. Make certain, by following the test procedures given in paragraph 46, that generator requires replacement.
(2) Open engine compartment. Elevate howitzer to provide clearance between gun and top of hull. Remove four screws attaching access plate over generator and remove plate (fig. 59). Open master battery switch. Turn handles to unlocked position and open hinged engine compartment doors.
(3) Remove generator belts. Loosen generator cradle adjusting nut and allow generator and cradle to drop to lowest position. Loosen knurled packing nut on front fan-shaft yoke at generator pulley end. Slide three drive belts off generator pulley.
Caution: Never pry belts off pulley with a screwdriver or other sharp tool, as pulleys may be accidentally nicked and burred.
(4) Remove generator. Remove two nuts and spacers holding generator mounting strap clamps to cradle clevis (fig. 78) and swing clamps back. Remove conduit guard and disconnect generator cables. Lift generator out of cradle.
b. Installations. {V) Mount generator in cradle. Lift generator into mounting cradle on engine, at the same time sliding fan shaft in rear of generator pulley into universal joint yoke splines and seating locating lug on cradle in locating hole in generator housing (fig. 79). Swing generator strap clamps into position on generator and insert clevis in toggle. Install spacer and nuts on clevis and tighten. Reconnect generator cables (fig. 66) and install conduit guard.
(2) Install and adjust belts. Lift each belt in turn up into its position on pulley. Tighten knurled packing nut at front fan-shaft universal joint yoke. Raise generator and cradle until there is %- to
153
APPARATUS BOX (COVER REMOVED) NO. 4 RED (4) NO. 6 BLACK (4)
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REGULATOR MOUNTING STUDS L* H- REGULAT°R
RA PD 331842
Figure 77. Regulator mounting.
%-inch slack in the belts, measured midway between generator and water pump pulleys (fig. 50).
(3) Close engine compartment. Reinstall generator access plate. Close engine compartment doors and turn handles to locked position.
82. Generator Regulators
a. Removal. Make certain, by following test procedures given in paragraph 46, that generator regulator requires replacement. Open master battery switches. Remove apparatus box cover. Remove six nuts (fig. 77) that hold regulator mounting assembly to apparatus box. Pull generator regulator assemblies out of apparatus box. Remove four bolts holding regulator to mounting bracket. Disconnect three wires at regulator terminals and remove regulator.
b. Installation. Connect three wires to regulator terminals, as shown in figure 77. Close master battery switch, and connect a jumper wire momentarily between “Generator” terminal and “Battery” terminal of regulator. This allows a momentary surge of battery current to flow to the generator and polarize it correctly. Position regulator
154
FA^HAFT PACKING NUT-? Y mounting straps
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DRIVE BELTS—A_ ADJUSTING NUT "
(MATCHED SET) RA pD 3313g!
Figure 78. Generator mounting.
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HOLE---jAA j flB|
ADJUSTING *
NUT-------f#
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LUG—' RA PD 331370
Figure 79. Installing generator.
155
assembly on mounting bracket and install four mounting bolts. Place regulator assemblies in apparatus box and install six nuts holding regulator mounting bracket assembly in box. Install apparatus box cover (fig. 77).
Note. Never attempt to readjust generator, regulators; service by replacement only.
Section XXI. BATTERY AND LIGHTING SYSTEM
83. Description and Data
a. Battery. (1) A 24-volt electrical system is employed. The battery consists of two separate 12-volt, 6-cell units, mounted one on each side of the vehicle, in a compartment in the hull just above the front end of the fuel tank (fig. 80).
(2) The two batteries, one on each side, are connected in series to provide the 24-volt potential. The circuit of the battery system is shown in figure 39.
b. Master Battery Switch. The master battery switch, located in a box mounted on the left side of the engine bulkhead between the air cleaner and hull side wall (fig. 5), is provided to open the battery ground circuit and thus cut off all electrical circuits.
c. Battery Outlet. The battery charging outlet is located in the same box as the master switch (fig. 5). This outlet provides for plugging in a slave cable to another vehicle or to a battery charger when the batteries are too low to function properly. The circuit is shown in figure 39.
d. Lighting System. (1) Driving lights. The driving lights consist of two headlights, with blackout marker lights incorporated, a blackout driving light, and two dual-purpose taillights. The left taillight contains a blackout taillight and a double filament combination service tail and stop light. The right taillight contains a blackout taillight and a blackout stop light.
(2) Blackout driving light. The blackout driving light When not in use is carried in a bracket mounted on the left hull wall in back of the driver’s seat, and is put in use by substituting for the headlight in the left headlight mount. A resistor is inserted in the circuit to reduce the voltage to the light from 24 to 6 volts. This reduction in voltage is necessary, due to the special design of the blackout driving light, in order to obtain the proper illumination. The resistor assembly is mounted behind the instrument panel at the junction of the upper and lower deck of the hull. This circuit is shown in figure 41.
(3) Instrument panel lights. There are two lamps in the instrument panel that provide illumination for all the instruments. These lamps are controlled by a rheostat switch located in the upper left-hand
156
MASTER SWITCH CABLE
BATTERY
RADIATOR
AND GROUND ^-CONNECTING CABLE FILLER COVER-?
Mg: V Ms*.
****'■• IFU
BATTERY COVER A BATTERY-/ FUEL VALVE J ^HJEL FILLER
ANGLES
HOLD-DOWN CLAMP CONTROL CABLE COVER
Figure 80. Battery mounting.
corner of the panel. These lamps are available by removal of the access plugs.
(4) Dome lights. Two dome lights are provided, located in the driving compartment of the hull, one on the upper deck just above and forward of the assistant driver and the other on the bottom of the emergency ignition switch box. Each dome light has two lamps and two lenses (clear and red).
e. Circuit Breakers. Seven circuit breakers are incorporated in the electrical system in place of the conventional fuse arrangement. The circuit breakers (except those in the charging circuit) are all of the manual-reset type, which means that the protected circuits can be closed again after the circuit breaker has operated simply by pressing the reset button. The charging circuit breakers are fully automatic. The various circuit breakers are located as follows:
(1) Lighting. The circuit breaker for the driving lights is located in the lower left corner of the instrument panel (fig. 6).
752022 0—47------11
157
(2) Siren. The circuit breaker for the siren is also located in the lower left corner of the instrument panel.
(3) Fuel pump. The circuit breaker for the fuel pumps is located in the center of the fuel pump switch bracket (fig. 7).
(4) Ventilator. The circuit breaker for the ventilator motor is located on the ventilator assembly, on the driver’s side, toward the front of the vehicle.
(5) Hull domelights. The circuit breaker for the hull dome lights and the windshield wiper (cold-weather accessory) is located on the front face of the emergency ignition switch box (fig. 12).
(6) Charging circuit. Two circuit breakers in generator armature circuit are mounted one on each regulator.
/. Data. (1) Batteries.
Type--------------------------------- 6-cell.
Voltage—each___________________________ 12.
Voltage—entire system___________________24.
Number of batteries_____________________2.
Numberof plates per cell________________ 17.
(2) Master battery switch.
Type---------------------------------------- Single-pole, single-throw
(3) Circuit breakers, {a) Capacity.
Siren--------------------------------------15 amp.
Driving lights-----------------------------30 amp.
Fuel pump----------------------------------15 amp.
Ventilator---------------------------------15 amp.
Dome lights and wiper______________________15 amp.
Generator----------------------------------70 amp.
(6) Type, all except charging circuit___Bimetal disk.
(c) Reset, all except charging circuit__Manual.
(<7) Type, charging circuit-------------Automatic reset.
(4) Lights.
Blackout marker light---------------------- 3-cp single-contact.
Taillight---------------------------------- 3-cp double-contact.
Blackout stop lights_______________________ 3-cp.
Service headlights_________________________40-watt.
Type---------------------------------------Sealed beam.
Service stop light-------------------------21-cp double-contact.
Instrument panel lights--------------------3-cp single-contact.
Signal lights------------------------------ 3-cp double-contact.
Blackout taillights________________________3-cp.
Blackout driving light--------------------- 6-volt with resistor.
Dome lights--------------------------------6-cp single-contact.
Spotlight, type---------------------------- Sealed beam.
158
84. Batteries
a. General. The service which the using arm can perform on the battery includes recharging or replacement, replacing cables, adding water, checking specific gravity, and cleaning.
6. Checking Batteries. Never use matches or a flame as a light when checking the battery. Distilled or clean water can be added to bring the fluid level just above the battery plates. If the specific gravity of any cell is 1.200 or below, the battery should be recharged. A fully charged battery should have a specific gravity reading from 1.275 to 1.300. Batteries can be charged in the vehicle by connecting on outside source to the battery outlet. Master battery switch must be ON when recharging batteries by this method.
c. Battery Terminal Corrosion. Warm water poured slowly over the terminals will loosen any copper sulphate that has been deposited, so that it can be brushed off and flushed away.
Caution: This should never be done with the battery in the vehicle. Battery posts and terminals should be wiped clean with a cloth saturated in an alkaline solution, such as ammonia or a solution of bicarbonate of soda and water. Corrosion can be retarded by applying a heavy coating of general purpose grease (No. 1). If battery fluid has overflowed or has spilled, all affected metal parts should be flushed with an alkaline solution and wiped dry. Remove drain plate on bottom of hull under fuel tanks to allow water to drain from fuel tank compartment.
d. Removing Battery Cables. The battery connector cable and master battery switch cable can be replaced by the using arm in the following manner: Turn master battery switch to OFF position. Remove battery box cover. Cover is held in place by a lever and cam arrangement. Pull lever to release cam and slide cam and lever to free cover from latch.
Note. It is not necessary to remove batteries from vehicle to replace cables.
Remove battery ground cable by removing nut holding cable to battery post, and pulling cable into engine compartment. Back off knurled nut attaching cable to the master switch box and lift out cable. Loosen screws holding connector cable to posts on batteries, and remove cable from attaching clips.
e. Installing Battery Cables. Install connector cable in clips on rear of bulkhead, and attach to battery post on each side (fig. 39). Attach master switch cable to switch, thread cable through opening in bulkhead and connect to negative battery terminal post. Install battery box cover.
/. Removing Battery. Turn master battery switch to OFF position. Remove battery box cover. Cover is held by a lever and cam
159
arrangement. Pull lever to release cam and slide cam and lever to free cover from latch. Remove hold-down bolts and lift battery holddown out of position (fig. 80). Remove cables from battery posts by loosening bolt in connection. Place cables out of position. Lift battery out of battery box and remove from vehicle.
g. Installing Battery. Turn master battery switch to OFF position. Lift battery into place in battery box. Connect rear battery cables, following wiring diagram (fig. 39). Install battery hold-down clamps.
Caution: Do not draw up hold-down too tightly or battery cell covers may crack. Install battery connector cable and master battery switch cable and tighten securely. Lift battery box cover into position and lock with cam lever.
85. Master Battery Switches
a. General. The master battery switch is located on a bracket mounted on the engine bulkhead at the left rear corner of the driving compartment, between the left engine air cleaner and hull side wall.
Z>. Removal. Place master switch handle in “OFF” position (fig. 5). Disconnect ground strap by removing bolt holding strap to hull sidewall. Remove four bolts, two above and two below, that anchor bracket to bulkhead, and pull bracket toward front of vehicle. Remove nut holding cable and/or ground strap to terminals or master battery switch that is to be removed. Remove cable and tape end. Remove screw holding switch handle knob and remove knob. Remove two bolts holding master battery switch in position and remove switch.
c. Installation. Position switch in bracket. Install two bolts through bracket and switch and tighten securely. Remove tape from cable ends and install cables and/or ground strap on switch terminals. Place bracket in position on bulkhead and install four bolts, two above and two below. Install switch handle knob. Connect ground strap to hull side walk
86. Circuit Breakers
a. General. Inoperative circuit breakers can be serviced by replacement only. They should not be disassembled.
Note. When replacing circuit breakers, be sure master battery switch is in OFF position.
b. Removal. (1) Domelights. Remove four screws holding dome light in position on emergency ignition switch box and lower dome light and bottom cover of box (fig. 12). Remove two screws holding circuit breaker in position in box; remove circuit breaker and disconnect wires.
160
(2) Fuel pumps. Remove four nuts holding control assembly to mounting bracket. Lower assembly to obtain enough clearance to disconnect the two wires and remove two screws holding circuit breaker in the assembly. Remove circuit breaker.
(3) Lights and siren. Remove instrument panel (par. 89). Both circuit breakers are now accessible and can be removed by removing two mounting screws for each and then disconnecting wires from terminals.
(4) Ventilator. Remove two mounting screws. Remove both wires and remove circuit breaker from assembly.
(5) Charging circuit. Remove regulator terminal cover. Disconnect two leads and remove two screws and washers holding circuit breaker to top of regulator box (fig. 77).
c. Installation. (1) Dome lights. Install wires on circuit breaker terminals and tighten securely. Install two mounting screws holding circuit breaker in position on emergency ignition switch box. Place dome light and bottom cover in position on box and secure with four screws.
(2) Fuel pumps. Install wires, lock washers, and screws on circuit breaker. Place circuit breaker in position on control assembly and install two mounting screws. Position control assembly on mounting bracket and install four nuts.
(3) Lights and siren. Install wires, lock washers and screws and tighten securely. Place circuit breaker or breakers in position on panel, install two mounting screws. Install instrument panel (par. 89).
(4) Ventilator. Install wires, lock washers, and screws. Position circuit breaker on ventilator assembly and install with two screws.
(5) Charging circuit. Position circuit breaker on top of regulator box and install two screws and washers. Connect short lead from regulator to right-hand terminal, and lead from generator to lefthand terminal (fig. 77). Install regulator terminal cover.
87. Lights
a. General. All taillight and headlight assemblies are composite assemblies of lamps, lenses, and reflectors and are sealed against dirt and moisture. Therefore, the only service operation on the lights is replacement of the sealed assembly. The complete headlight assemblies can be removed for safety in combat zones. Service operations on the lighting switches are covered in paragraph 101.
b. Removal of Complete Headlight. To remove the headlights, turn locking handles inside hull to the left to loosen. Back off knurled nut on lighting conduit. Remove conduit from headlight assembly. Lift assembly out of mounting.
c. Installation of Complete Headlight. See that light switch on instrument panel is “OFF”. Place headlight in position on hull
161
MARKER LAMP SOCKET
HEADLIGHT
RETAINER—7
—V'X'O
BLACKOUT MARKER LAMP
BASE
HEADLIGHT BODY
BLACKOUT MARKER LIGHT BODY
GASKET
RAPD 331307
HEADLIGHT
SLEEVE PLUG
• MARKER LIGHT DOOR
HEADLIGHT
DOOR
Figure 81. Headlight assembly—disassembled.
RETAINING RING
HEADLAMP UNIT
front plate. Secure in position by turning locking handle. Place lighting conduit in position and tighten knurled nut securely.
d. Removal of Headlight Sealed Unit. Remove screw holding headlight door to headlight body (fig. 81). Swing lower end of door outward and lift door from body. Pull sealed unit assembly outward until terminal screws holding wires to sealed unit assembly can be removed. Disconnect wires and remove sealed unit assembly.
e. Installation of Headlight Sealed Unit. Connect red wire in headlight body to terminal on center of sealed unit assembly. Connect black lead in headlight body to sealed unit assembly. Position headlight door body by inserting lug on top of door through slot in top of body. Install screw holding headlight door to body.
f. Removal of Complete Taillight Assembly. Remove three screws holding base of taillight assembly to hull. Turn taillight assembly over and remove two nuts and lock washers holding body to base. Slide base away from body, and disconnect both wires from body by turning and pulling connections until they slip out of plugs.
g. Installation of Complete Taillight Assembly. Connect wires to taillight by inserting wires in sockets, and turning them so that they will be locked in place.
Note. Be sure to connect wires to right sockets to assure proper operation of lighting system. Refer to wiring diagrams, figures 40 and 41.
Slide taillight base on body and install two nuts and lock washers. Position taillight on hull and install three screws holding base to hull.
162
h. Removal of Taillight Lamps. Remove two screws holding taillight door to light body and pull door off body (fig. 82). On righthand taillight, pull the right blackout lamp from the lower portion of the body and the blackout stop lamp from the upper portion of the body. These are sealed assemblies. On left-hand taillight, remove the blackout lamp from the lower portion of the body and the service tail and stop lamp from the upper portion of the body.
i. Installation of Taillight Lamps. On right-hand taillight, position the blackout tail lamp in lower portion of body and the blackout stop lamp in the upper portion of the body. On left-hand taillight, position the blackout tail lamp in the lower portion in the body and the service tail and stop lamp in the upper portion of the body. Position taillight door on body and install two mounting screws and lock washers.
j. Replacement of Dome Light Lamps. Remove two screws holding dome light door, and lift off door, rubber gaskets, and both lenses. Replace lamp. Reinstall door, gaskets, and lenses.
J|||l W -----TAILLIGHT
BLACKOUT STOP LIGHT UNIT-v jbk DOOR
TAILLIGHT BODY^ \
\ ! \\ Jr? I
(ZW jn
\ \ V SZ------BLACKOUT
> \ TAILLIGHT UNIT
RHTA,LLIGHT
e— TAILLIGHT
VNB \ door
SERVICE STOP AND A
TAILLIGHT UNIT-7^ ■ \
1 \ \ Is /*---------BLACKOUT
B \ TAILLIGHT UNIT
1/
\ L. H. TAILLIGHT
TAILLIGHT
BODY *■ RA PD 3313Q6
Figure 82. Taillight assemblies—disassembled.
163
Section XXII. INSTRUMENTS AND INSTRUMENT PANEL
88. Description
a. The instrument panel is mounted in the driving compartment directly ahead of the driver. It carries the following instiuments and controls: two ignition switches, two starter buttons, two temperature gages, two engine and two transmission warning signal lights, two tachometers, a speedometer, an ammeter, the main lighting switch, the panel-light switch, circuit-breaker reset buttons for the lights and siren, and an outlet for connecting auxiliary electrical equipment.
6. Diagnosis information on all electrical instruments is given in the section on trouble shooting (par. 47). Replacement instructions on the dial instruments appear in paragraphs 90 through 93; on the lamps in paragraph 93; on the circuit breakers in paragraph 86; on the switches in paragraphs 98 through 102; and on the complete panel in paragraph 89.
89. Instrument Panel
a. Removal. Open master battery switches. Working from driver’s seat, remove cap screw and lock washer at lower center mounting bracket. Remove two screws and lock washers at upper center mounting bracket, and one at upper right bracket. Loosen upper left mounting screw, slide panel and bracket assembly to the left, and pull forward. Place panel face down in lap, disconnect three flexible cables to speedometer and tachometers, and six flexible electrical conduits. Remove panel from vehicle.
6. Installation. Reinstall three flexible cables for speedometer and tachometers. Reconnect six electrical conduits (figs. 84 and 85), making certain that plugs are correctly indexed. Position panel against and to the left of tapping blocks on hull front plate and slide to the right, engaging the slot at upper left bracket behind flat washer and lock washer of mounting cap screw. Install remaining cap screws; two at upper center bracket, one at upper right, and one at lower center. Tighten all cap screws securely.
90. Ammeter
a. Removal. Remove instrument panel from vehicle (par. 89). Remove tw’o terminal nuts (fig. 85) and disconnect lead wires from ammeter. Remove two mounting nuts from terminal studs, slide mounting clamp off studs, and remove ammeter from front of panel.
164
b. Installation. Position ammeter in opening in panel and install mounting clamp at rear. Install t wo mounting nuts on terminal studs, position lead wires on studs (fig. 85), and install terminal nuts. Reinstall panel in vehicle.
Note. Wires have circuit numbers marked at ends to aid correct assembly.
91. Engine Temperature Gages
a. Removal. Remove instrument panel from vehicle (par. 89). Remove two terminal nuts and take off two gage lead wires. Remove two mounting nuts, one of which is located on the terminal stud at the side of the gage. Pull mounting clamp back off studs and remove gage from front of panel. This procedure applies for either gage.
b. Installation. Position temperature gage in opening in panel, and place mounting clamp over studs at rear. Install two mounting nuts on studs and tighten snugly. Connect lead wires according to circuit numbers and markings on gage unit. Install terminal nuts. Reinstall panel in vehicle. This procedure applies for either gage.
92. Speedometer and Tachometers
a. Removal. Remove instrument panel from vehicle (par. 89). Remove two mounting nuts and washers (fig. 85), and remove mounting bracket from rear of instrument. Remove instrument from front of panel. This procedure applies to speedometer and both tachometers.
r— UPPER MOUNTING BRACKETS—v
/ r~ ACCESS PLUGS FOR \
/ \ PANEL LIGHTS \ >
I cj. gg-g
--—L_---—----------)........... .. .......
0*1 jZT ilKWl IU O
; XX. A w C t
\ P//> o 7
—...—y
V/ \ \1 s'
Z CIRCUIT BREAKER PANEL REAR COVER /./ ATTACHING ATTACHING SCREWS ATTACHING SCREWb
SCREWS
Figure 83. Instrument panel and attaching parts.
165
b. Installation. Position instrument in proper opening in front of panel. Place mounting bracket on rear of instrument with holes for screws and mounting studs properly lined up. Install two mounting screws and washers. Reinstall panel in vehicle.
93. Lamps
a. Removal. The lamps for the warning signals and for panel illumination can be replaced readily without disturbing the panel itself. First use a screwdriver to pry the access plug for the panel lamps, or the ruby lens for the warning signals (fig. 83) from the panel. Then depress the lamp slightly, turn counterclockwise to release bayonet-type catch, and remove lamp.
b. Installation. The lamps used for panel lighting and for warning signals are 24-volt, 3-candlepower. Line up ribs on lamp with slots in socket, depress lamp and turn clockwise until locked securely. Install access plug or ruby lens by snapping into place.
Section XXIII. MISCELLANEOUS ELECTRICAL EQUIPMENT
94. Description
a. General. This section includes description and replacement instructions covering all electrical equipment not covered in previous sections. Testing procedures for locating faults in these pieces of equipment are given in paragraph 47.
b. Electrical Wiring. Electrical wiring is carried in shielded conduits or cables. Several wires are grouped together and run through a metal sheath with index plugs at each end to form a conduit. This shielding serves to protect the wires from dirt, grease, and other elements which might cause defective wiring. Each circuit is numbered and the circuit numbers are marked on the ends of all wires. These numbers are indicated in the wiring diagrams, figures 37 and 47.
c. Signal Units. The signal sending units consist of an engine temperature gage unit and a heat signal switch mounted at the upper front of the left cylinder head, an engine oil pressure warning signal switch mounted at the rear of the engine block, and a transmission oil pressure warning signal switch mounted at the left rear on the transmission case (fig. 108). The temperature gage unit is essentially an electrical resistor which changes its resistance with changes in temperature. These changes are indicated by the gage on the instrument panel which simply measures the resistance in the gage circuit. The heat signal switch is a gas expansion-type switch in which the gas expands as the temperature increases until at 238° to 242° F. a set of contact points close, forming a completed circuit. The oil-pressure signal switches are simply low-pressure switches. With little or no pressure these switch contacts are closed, permitting the warning signals to
166
light. The engine oil pressure switch breaks the circuit at a pressure of 8 to 10 pounds. The transmission unit breaks the circuit at 62 to 68 pounds. At all pressures above these, the warning lights are out.
d. Siren. The warning siren is mounted on the front deck next to the left headlight. It is operated by a spring-loaded momentary contact switch on the full floor in front of the driver.
e. Ignition-Switches. The two ignition switches, one for each engine, are located in the lower-right corner of the instrument panel (fig. 83) and are protected from accidental operation or damage by a sheet metal guard. The switches have two positions: OFF with the switch levers vertical and ON with the levers turned 90° clockwise.
f. Emergency Switch. An emergency ignition switch, which controls the feed to the two regulator switches, is mounted in a control box together with the circuit breaker for the dome lights on the hull roof behind and to the right of the driver (fig. 12). This switch must always be kept in the ON position, except in an emergency.
g. Starting Switches. Two starting switches of the push-button type are provided, one for each engine. These switch buttons are located at the lower right of the instrument panel, just above the ignition switches.
h. Lighting Switches. There are two lighting switches on the instrument panel: one at the upper left for the panel lights, and one at the upper right for the main lighting system. Operation of these switches is covered in paragraph 47. Dome lights in the hull and turret of the vehicle are not controlled by these switches, but by individual switches integral with the lights.
PANEL CASE
TACHOMETER CABLES
RIGHT MAIN CONDUIT
CONDUIT
ERGENCY IGNITION SWITCH
BOX CONDUIT rapd 331333
Figure 8J/. Cables and conduits at rear of instrument panel.
167
i. Fuel Switch. The fuel switch levers, one each for the right and left fuel tanks, are mounted on the hull roof in front and to the right of the driver (fig. 7). These switch levers not only control the circuits to the electric fuel pumps but also open and close the fuel shut-off valves by means of a cable running back to the valve at each tank.
j. Apparatus Box. An apparatus box (fig. 86) is mounted on the front of the bulkhead at the extreme right of the driving compartment, ft contains the two generator regulator assemblies, the two starter relays, and the ammeter shunt.
k. Ventilator. The ventilator is located in the hull roof between the driver’s and auxiliary driver’s doors (fig. 12). The unit is self-contained, and operates by means of a reversible electric motor which can either draw air in or blow it out of the vehicle.
95. Conduits, Cables, and Junction Boxes
a. Removal. All electrical conduits are removed in essentially the same manner. Unscrew the connectors at each end and detach connector plugs. Remove the retaining clips, after taking out any stowage items or sheet metal parts that interfere, and remove conduit from vehicle.
6. Installation. Position conduit in hull or turret and install retaining clips. Assemble connectors snugly into place. Observe the following precautions:
(1) Make sure conduits are connected to proper receptacles. Refer to pertinent wiring diagrams (figs. 37 through 47).
(2) When installing connector plugs, make sure that the letters on the plug and receptacle coincide and that the tongue and groove line up. Do not force plugs. If plug is properly lined up, it will slip into receptacle without forcing.
(3) Do not twist or kink conduit. See that all retaining clips are tightened in proper position.
96. Apparatus Box
a. Removal. Disconnect the three conduits (fig. 86) at the top and upper side of the apparatus box. Remove the terminal cover and disconnect the five wires (fig. 86) at the ammeter shunt terminal block. Remove the two mounting screws and washers at the lower flange and the three screws and washers at the upper flange, and remove the apparatus box from the bulkhead.
b. Installation. Position the apparatus box on the bulkhead, and install the three upper and two lower mounting screws and washers. Connect the five wires (fig. 86) to the terminal block according to the circuit numbers and install the terminal cover. Connect the three conduits to the correct plugs in the apparatus box.
168
VMAIN LIGHTING SWITCH r,xkll_,
\ r- TERMINAL BLOCKS-7 PANEL
PICHT \ TEMPERATURE F 7 TEMPERATURE LIGHT
MAIN -X\,^GE~\ 1 vS^EDOMETER 7 r<-GAGE /-SWffCH
...
/ a '• e‘^^3335c| J \
I / ^s—. ■„■■-. I -~rrrrrrr"- -■"iWiitiifi-ni-,"-y,A ■ .. i -:-.ii-'i ?"trr.WWW -4-4^ LEFT
/ / ^TO EMERGENCY \ AMMETER \ TO SHUNT BOX3 1 MAIN
/ Z-TO SIREN IGNITION \_TA-urx..CTCne J Tr> conkiT pkir-J / SWITCH TACHOMETERSJ TO FRONT END
'-TO COMPASS LIGHT BOX
Figure 85. Instrument panel connections—rear cover removed.
97. Signal Sending Units
a. Removal of Engine Temperature Gage Unit. Make certain by test (par. 47) that engine gage unit is at fault. Open engine compartment door. Disconnect wire to gage unit. Remove water drain plug at bottom of transmission and drain coolant below level of cylinder heads. Remove gage unit from cylinder head.
b. Installation of Engine Temperature Gage Unit. Install gage unit in opening in upper front corner of left cylinder head.
Note. Gage unit is cadmium-plated to distinguish it from warning signal unit, which is brass.
Do not use gasket paste or sealer on threads of unit, but tighten sufficiently to secure a good seal. Connect gage wire according to wiring diagram (fig. 45). Refill cooling system and close engine compartment door.
c. Removal of Engine Heat Signal Unit. Make certain, by test (par. 47) that the signal unit is at fault. Open engine compartment door. Disconnect wire to signal unit. Remove water drain plug at bottom of transmission and drain coolant below level of cylinder heads. Remove signal unit from cylinder head.
d. Installation of Engine Heat Signal Unit. Install signal unit in opening in upper front corner of left cylinder head.
Note. Warning signal unit is brass to distinguish it from temperature gage unit, which is cadmium-plated.
Do not use gasket paste or sealer on threads of unit, but tighten sufficiently to secure a good seal. Connect signal wire according to wiring diagram (fig. 44). Refill cooling system and close engine compartment door.
169
e. Removal of Engine Oil Pressure Warning Signal Switch. Make certain, by test (par. 47), that switch is at fault. Open engine compartment cover. Reaching down from top of vehicle, disconnect wire to switch and then remove switch from L connection at rear of engine V.
f. Installation of Engine Oil Pressure Warning Signal Switch. Reaching down from top of vehicle, install switch on L connection, turning down first by hand, and then tightening with wrench only enough to secure a good seal. Connect lead wire to terminal on switch. Close engine compartment door.
g. Removal of Transmission Oil Pressure Warning Signal Switch. Make certain, by test (par. 47), that switch is at fault. Remove cover plate from floor of hull underneath engine. Reaching up through opening, remove dirt from around switch, disconnect lead wire, and unscrew switch.
h. Installation of Transmission Oil Pressure Warning Signal Switch. Reaching up through opening in hull, install switch, turning down first by hand, and then tightening with wrench only enough to secure a good seal. Connect lead wire to terminal on switch. Reinstall cover plate in hull floor.
98. Siren and Siren Switch
a. Removal of Siren Switch. Open master battery switch. Remove two screws and lock washers holding siren switch brackets to
COVER BULKHEAD UPPER MOUNTING SCREWS AIR CLEANER
TITJF/rf \
\ TERMINAL-COVER-
■ fA \ REMOVED
-Ki . WiSSol
■ fl
APPARATUS BOX TERMINAL COVER RA PD 331810
Figure 86. Apparatus box and connections.
V70
hull floor. Turn switch and'bracket assembly over, and remove two nuts holding switch conduits to terminals. Loosen siren conduit clip mounting stud nut and slide both conduits out of clip. Remove two screws holding switch to bracket and remove switch.
6. Installation of Siren Switch. Position siren switch on bracket assembly and install two mounting screws. Connect both siren cables to terminals on switch and tighten terminal nuts.
Note. Cables may be installed on either terminal.
Slip both conduits under clip on bracket and tighten clip screw. Position entire assembly on hull floor, and install two mounting screws and lock washers.
c. Removal of Siren. Remove siren switch from bracket assembly (a above) and remove cable to siren by removing terminal nut. Loosen screw holding siren conduit clip to hull, and slip conduit out of clip. Remove nut from lower end of siren mounting tube, and pull siren and conduit out of opening in front hull plate.
d. Installation of Siren. If rubber seal at siren opening is damaged or torn, replace it. Slip conduit through opening and lower siren into position. Slide mounting nut over conduit and tighten on lower end of mounting tube. Position conduit under clip and tighten clip. Reconnect conduit to switch and reinstall switch.
99. Ignition Switches
a. Removal of Ignition Switch. Turn master battery switch OFF. Remove instrument panel (par. 89). Take out three mounting screws for right-hand conduit box at back of instrument panel (fig. 85), and pull box out far enough to permit access to rear of ignition switches. Disconnect wires at switch that is to be removed. Turning to face of panel, remove two screws holding guard to panel (fig. 83). Unscrew gnurled nut around switch lever and remove nut. Push switch and lever back and out of panel.
b. Installation of Ignition Switch. Insert switch in opening from rear of panel, and position with switch lever pointing up. Install knurled nut over switch lever and turn down snugly against face of panel. Install switch guard, tightening mounting screws securely. Turn panel over, and connect wires to switch in accordance with wiring diagram and markings (fig. 38). Position conduit box on mounting studs and install three attaching screws. Install instrument panel in vehicle.
c. Removal of Emergency Ignition Switch. Turn master battery switch OFF. Remove four cap screws and lock washers that hold emergency ignition switch box cover in place and remove cover and dome light from box as an assembly. Disconnect wires to switch, and remove switch after taking out hex nut at front.
171
d. Installation of Emergency Ignition Switch. Install switch through opening in switch box and attach with hex nut. Connect wires to switch in accordance with wiring diagram and markings (fig. 38). Position cover and dome light assembly against switch box and install four cap screws and lock washers.
100. Starting Switches
a. Removal. Turn master battery switch OFF. Remove instrument panel from vehicle (par. 89). Take out three mounting screws for right-hand conduit box at rear of instrument panel (fig. 85), and pull box out far enough to permit access to starting switches. Disconnect wires at rear of switch to be removed. Turning to face of panel, remove rubber dust seal, loosen the large hex nut surrounding switch button, and remove nut. Push switch back and remove from rear of panel.
b. Installation. Insert switch in opening from rear of panel, and install large hex nut and rubber dust seal at front, turning down until snug against face of panel. Turning to back of panel, connect wires to switch terminals according to wiring diagram and markings (fig. 37). Position conduit box on mounting studs and install three attaching screws. Install instrument panel in vehicle.
101. Lighting Switches
a. Removal. Both the panel light switch and the main light switch are removed by the same procedure. Turn master battery switch OFF. Remove instrument panel (par. 89). Disconnect wires from terminals at rear of switch. Remove hex nut from switch lever shaft, remove switch plate, and take switch out from rear of panel. Take screw out of center of switch lever (fig. 83) and remove lever from face of panel.
b. Installation. Insert switch in opening from rear of panel, position switch plate against face of panel, and install retaining nut on switch lever shaft. Place switch lever on shaft and secure in position with round-head screw. Test lever for proper operation. Connect wires to switch terminals, in accordance with the wiring diagram (fig. 40). Install instrument panel in vehicle (par. 89).
102. Fuel Switches
a. Removal. I urn master battery switch OFF. Disconnect both fuel valve rods at switch levers. Disconnect electrical conduit at emergency ignition switch box. Remove four cap screws and lock washers, and remove switch assembly from hull roof. Remove individual switches or circuit breaker by disconnecting wires and removing attaching screws.
172
b. Installation. Install individual switch or circuit breaker, and connect wires as indicated in diagram (fig. 46). Position switch assembly against hull roof with mounting holes correctly alined, and install four cap screws and lock washers. Connect conduit to receptacle at rear of emergency ignition switch box. Connect fuel shut-off rods to switch levers. Check operation of fuel valves, and readjust rods if necessary.
103. Ventilator
a. Removal. Turn master battery switch OFF. Disconnect conduit at elbow on left side of ventilator. Remove four cap screws and lock washers around upper mounting flange, and remove ventilator from vehicle as an assembly.
b. Installation. Position ventilator assembly on mounting flange in hull roof, install four cap screws and lock washers, and tighten securely. Connect conduit from emergency ignition switch box to elbow on side of ventilator.
Section XXIV. RADIO INTERFERENCE SUPPRESSION
104. Purpose
The purpose of radio interference suppression is to eliminate or minimize electrical disturbances within vehicle which would interfere with radio reception, or would disclose the location of vehicle to sensitive electrical detectors. Therefore, it is important that vehicles with, as well as vehicles without, radios be suppressed properly to prevent interference with radio reception of neighboring vehicles.
105. Description
Suppression is accomplished by use of capacitors (condensers), bonding jumpers (ground straps), and by toothed lock washers. Wiring, which may carry interfering electrical surges to a point where interference will affect radio reception, is shielded. The toothed lock washers and ground straps located throughout the vehicle tend to bind the entire unit together into a solid shield.
106. Suppression Components
Location of suppression components is given below.
a. Ignition System. (1) The high-tension leads from distributors to spark plugs are inclosed in loose-braid metal shielding which terminate at the ferrules provided at each distributor and spark plug (fig. 89).
752022 0—47——12
173
(2) The high-tension lead from each distributor to each ignition coil is enclosed in loose-braid metal shielding and terminated at ferrules provided at each distributor and coil.
(3) The low-tension lead from each distributor to each ignition coil is enclosed in loose-braid shielding and terminated at ferrule provided on each distributor and ignition coil.
(4) The low-tension lead, from each ignition coil to each ignition switch, is enclosed in flexible metal-tube shielding, terminating 10 inches from each coil but grounded to each engine block through a pressure clip and at the instrument panel by means of fittings.
(5) The two ignition coils are integrally shielded and incorporate ferrules at electrical connections for terminating shielding of external wiring with the exception of primary lead from coil, where the shielding terminates approximately 10 inches from the coil. One capacitor is built into each coil and is connected to battery terminal of each coil. Each coil is mounted on a bracket which bolts to engine head. Both coils and brackets are grounded by means of toothed lock washers.
(6) Each distributor cap and base is integrally shielded and incorporates ferrules at electrical connections for terminating loosebraid shielding of external wiring. One resistor suppressor is molded in each tower of both distributor caps, each cap having nine towers.
(7) The 16 spark plugs are integrally shielded with suitable ferrules at electrical connections for terminating shielding of high-tension leads. One resistor suppressor is internally mounted in each integrally shielded spark plug.
b. Engine Bonding. Each engine is bonded to hull by a ground strap from each engine support post (fig. 88) to hull floor. Each engine mounting stand is grounded to transfer case by a ground strap (fig. 65). Each air intake tube is grounded to hull crossmember by a ground strap (fig. 89).
c. Charging System. (1) The two regulators are enclosed in an apparatus box which fastens to hull by means of plated bolts and cleaned surfaces under heads of bolts (fig. 86). The generator terminals are completely covered by a shield which fastens to generator by means of a spring clamp. The armature and field leads between regulator and generator (fig. 88) are jointly enclosed in metal hose .shielding, terminated in a fitting at the generator and at shielded terminals at the apparatus box which houses the two regulators (fig. 90).
(2 ) Two 0.1-Microfared concentric capacitors are mounted in the housing of each generator and are connected to positive brush terminals of each generator.
(3 ) One 0.1-Microfarad feed-through capacitor is mounted in each regulator sub-base and connected in lead to armature terminal of each regulator. One 0.1-Microfarad feed-through capacitor i.s mounted in
174
CAPACITOR
TOOTHED LOCK WASHERS
| Figure 87. Radio terminal box.
d
h
P
11 I
each, regulator sub-base and connected in lead to battery terminal of each regulator. One 0.0019-Microfarad capacitor is mounted in each J regulator sub-base and connected in series with a 4-ohm resistor to the field terminal of each regulator. Each regulator is grounded to regulator mounting bracket by ground straps from two of the regulator mounting feet to the mounting bracket (fig. 90). Both regulators are mounted on the bracket and this bracket is welded to the base of the apparatus box.
d. Howitzer Elevating Mechanism. (1) Two 0.1-Microfarad capacitors are mounted on howitzer elevating motor housing, and are connected, one each, to the motor control supply terminals (forward and reverse). The howitzer elevating motor is grounded to gun mount by plated bolts and washers.
1 (2) Two 0.1-Microfarad capacitors are mounted inside the gun
switch box and connected, one each, to the motor control supply terminals (forward and reverse). One 0.1 Microfarad capacitor is mounted
175
inside the howitzer switch box and connected to the battery terminals. The howitzer switch box is grounded to hull with internal-external plated toothed lock washers under heads of bolts. After vehicle serial No. 70 all wiring leads associated with the howitzer elevating mechanism are enclosed in flexible metal shielding.
e. Ventilating Fan Motor. One 0.5-Microfarad capacitor is mounted in the ventilating fan motor case and connected to switch of motor.
f. Radio Terminal Boxes. Two 0.1-Microfarad capacitors are mounted in each of the radio terminal boxes and connected, one each, to the 12- and 24-volt terminals (fig. 87).
g. Bonding by Ground Straps. Ground straps are used at following points:
(1) Engine support post to hull floor (fig. 88).
(2) Engine mounting stand to transfer case (fig. 65).
(3) Air-intake tube to hull crossmember (fig. 89).
(4) Distributor to hull crossmember (fig. 89).
(5) Generator to generator bracket (fig. 88).
(6) Regulator mounting feet to mounting plate (fig. 90).
GROUND STRAP—GENERATOR TO MOUNTING BRACKET
F M - ____ -
‘Ip ... w** w J
Tt , i IBl
n x fr
* -■ 'Jia
GROUND STRAP—ENGINE SUPPORT TO HULL FLOOR
LOOSE BRAID SHIELDING—ARMATURE AND FIELD LEADS
Figtire 88. Engine support and generator ground straps.
176
h. Bonding by Toothed Lock Washers. The attaching screws of all clips or clamps which support conduits and pipes and where clips are anchored to tapping blocks are provided with toothed lock washers. Toothed lock wrashers are used also to bound mechanical parts at the following points:
(1) Howitzer switch box to hull.
(2) Howitzer switch box cover to box.
(3) Howitzer limit switch box cover to box.
(4) Periscope to hatch door.
(5) Master switch box to hull.
(6) Regulator apparatus box to hull.
(7) Air ventilator assembly to hull.
(8) Fuel pump mounting plate to fuel tank.
(9) Fuel pump terminal casting to mounting plate.
(10) Fenders to hull.
(11) Bulkhead extension angle to transfer case shield.
(12) Attaching screws for all electrical nuts.
107. Maintenance
a. Ignition System. The following points of attachment must be kept securely tightened :
(1) Distributor bond strap at distributor end and at hull crossmember.
(2) All distributor high-tension leads at distributor tower end and coupling nut at spark plug end.
(3) Spark plug extension (suppressor) nut on spark plug.
(4) Screws attaching top half of support bracket for high-tension leads.
(5) Nuts attaching ignition coil-to-coil mounting bracket.
b. Charging System. Capacitors in engine generator housing and in regulators are internally mounted and, in case of failure of capacitors, the generator or regulator should be replaced.
c. Howitzer Elevating Motor and Switch Box. The capacitors attached to the howitzer motor leads and to the howitzer switch box leads can be replaced by disconnecting the above leads and replacing defective capacitor.
d. Radio Terminal Boxes. Remove terminal box cover and remove capacitors which are connected to positive terminals and anchored by box attaching screws. When new capacitors are installed, make sure that surfaces are clean, and that toothed lock washers are used on attaching screws. Connect capacitors to terminals as shown in figure 87.
e. Wiring System. Conduit support clip attaching screws must be kept tight and secured by the proper type lock washers. Conduit coupling nuts must be kept properly tightened.
177
108. Fuel System Description and Data
a. Description. (1) The fuel system is illustrated in figure 91. Two fuel tanks, of approximately 55-gallon capacity each, are carried in narrow, deep compartments on each side of the engine compartment.
(2) Two strainers are incorporated in the fuel pump support assembly in the fuel tanks. The first is a cylindrical strainer extending from the top of the fuel tank filler opening to the top of the fuel pump mounting cage (fig. 98). This strains the fuel as it is poured into the tank and also acts as a flame arrester. The second strainer surrounds the fuel pump mounting cage at the bottom of the tank. This strains the fuel in the tank as it passes to the pump, and is self-cleaning due to sloshing action of the fuel.
(3) Each carburetor is equipped with a small disk-type auxiliary fuel filter, which is mounted in a horizontal position on the carburetor float chamber fuel inlet fitting. This filter will retain the small particles of dirt which may pass through the main filter at the bottom of the fuel tank. The filter has a movable bowl to provide a means of cleaning.
GROUND STRAP-DISTRIBUTOR-TO-HULL CROSS MEMBER
GROUND STRAP—AIR INTAKE-TO-HULL CROSS MEMBER I
LOOSE BRAID SHIELDING
METAL-CLAD DISTRIBUTOR CAP
FERRULE
Figure 89. Air intake and distributor ground straps.
178
Section XXV. FUEL AND AIR INTAKE AND EXHAUST SYSTEMS
APPARATUS BOX (COVER REMOVED) GENERATOR REGULATORS
GROUND STRAP—REGULATOR FEET TO MOUNTING PLATE RA PD 331963
Figure 90. Apparatus box—regulator ground straps.
(4) A fuel line extends from each fuel pump through the top of the fuel pump support assembly, forward to a check valve, and then to the shut-off valve. From these shut-off valves, a connecting line is carried across the support at the front of the engine compartment. This line contains two T-connections, from which a rubber line extends to the auxiliary fuel filter at the carburetor float chamber (fig. 91). This makes it possible for either tank to supply fuel to both engines.
(5) The flow of fuel and selection of the tank is controlled by a pair of levers and switches at the front center of the driving compartment roof (fig. 7). From each of these levers, a control cable extends back to the shut-off valve and the feed wire for the pump extends back to the terminal on top of the fuel pump support assembly, from which it is carried in an insulated conduit to the pump.
b. Data. (1) Carburetor.
Make______________________
Type----------------------
Gas line connections______
Idle adjustment___________
Flange size_______________
Choke type________________
,. Carter.
. WCD duel downdraft.
. %-inch hose nipple.
_ Screw type.
. l^-inch.
. Automatic climatic control.
(2) Fuel pumps.
Make______________________________Carter.
Location__________________________In cage at bottom of fuel tank.
Type______________________________Centrifugal, electrically driven.
179
Number________________________
Control_______________________
Pressure______________________
Octane rating of fuel_________
(3) Fuel strainers.
Location______________________
Make__________________________
Type--------------------------
Number________________________
(4) Auxiliary fuel filter.
Location______________________
Make__________________________
Type--------------------------
Number________________________
(5) Air Cleaner.
Number________________________
Type--------------------------
Make__________________________
Filter elements_______________
Reservoir capacity____________
Location_______________________
2, 1 in each tank.
Switch and manual shut-off valve.
6 pound.
80.
Filler support, pump cage.
Ripley.
Self-cleaning screens.
4.
Carburetor float chamber.
Zenith.
Disk-type.
One each carburetor.
2.
Oil bath.
A. C. or Donaldson.
Steel mesh or Tampico fibre.
3 quart.
Front of bulkhead.
109. Air Cleaners
a. Description. Two large-capacity air cleaners are provided, one for each carburetor, mounted on the bulkhead at the rear of the driving compartment. These cleaners are of the oil-bath type. Air from the inlet grille above the radiators passes over the oil and through the filtering element and is carried through tubes in the engine compartments to the carburetors.
b. Servicing. Loosen the two wing nuts holding the air-cleaner reservoir to the air cleaner. While supporting the reservoir from bottom, swing out the clamp bolts and lower the reservoir. Remove screen from Donaldson air cleaner by turning screen counterclockwise, then pulling screen down out of air cleaner (fig. 92). Remove element from A. C. cleaners by pulling same downward. Pour out old oil and clean reservoir and screen with dry-cleaning solvent. Dry all units thoroughly with compressed air, if available; fill reservoir to level indicated, using approximately 3 quarts of engine oil (seasonal grade) and reinstall screen and reservoir.
c. Removal. The air cleaners are mounted to a bracket on the driving compartment side of the bulkhead by means of two metal straps
180
r—FUEL SHUT-OFF VALVE / r- TEE CONNECTIONS—\ 3-?®^7“ FUFL SHUT-OFF VALVE
FILLER CAP—i /
CHECK VALVE—x \Y A ' A
support ‘SaS— CARBURETORS—*l.-S-Tl
o U r r kJ KI 'aA- vbEhI 1 Mm
ASSEMBLY ■ \ jZl I T W V
\\®4 FUELUNEASSEMBLY IJ 1M —-\- RIGHT FUEL TANK A. \ \ 1 jgfH
Ik^wMMlL LEFT FUEL TANK-\ 1] fuJfl
Ml~li \ W/j
WBnRjH| FRONT OF VEHICLE y
ra pd 331852
Figure 91. Fuel system.
181
that encircle the unit (fig. 92). Working in driving compartment, loosen hose clamp holding air cleaner inlet pipe to air cleaner. Remove screw holding each strap around air cleaner and lift complete assembly from its mounting.
d. Installation. (1) Check inlet opening. The air cleaners are interchangeable as rights and lefts by interchanging the plate retained by eight screws with the inlet pipe on the cleaner. The outlet opening on the air cleaner is not removable, but is part of the cleaner itself. The outlet opening must always be connected to the carburetor inlet pipe.
Caution: If the air cleaner is installed incorrectly, oil will be drawn out of the air cleaner and into engine.
(2) Install cleaner. Coat the inside of the carburetor air intake hose connection with joint and thread compound (cement, type IT) and slide outlet on air cleaner into hose. Tighten hose clamp securely. Position two metal straps around air cleaner and tighten screws securely.
110. Carburetors
a. Description. The carburetors are Carter WCD type, of duel down-draft design, internally vented and fitted with dustproofing seals. Each of the duel barrels in the carburetor supply the fuel mixture to four cylinders through the intake manifolds. Each carburetor
AIR CLEANER SCREEN J AIR 'CLEANER RESERVOIR RA PD 331849
Figure 92. Servicing carburetor air cleaner.
RIGHT CARBURETOR AIR CLEANER LEFT CARBURETOR AIR CLEANER
CLAMPING STRAPS __________^r~RESERVOIR CLAMP BOLTS
is fitted with an auxiliary fuel filter which is located at the float chamber inlet.
6. Carburetor Adjustments. Test choke shaft with fingers at manual control to see that choke operates freely (fig. 94). Run engines until thoroughly warm; then adjust throttle stop screws (fig. 93) so engine speed is from 450 to 475 revolutions per minute, with the transmission selector lever in “DRIVE” position and parking brakes set. Tighten two idling mixture adjusting screws (fig. 93) as far as possible without forcing; then loosen screws 1^4 turns. Engines should run smoothly without loping or stalling. Readjust screws if necessary. Check to see that choke setting mark on choke thermostat housing is opposite mark on carburetor flange. If necessary, loosen three thermostat housing screw’s and rotate housing until marks line up (fig. 93). Tighten the screws.
c. Removal. Disconnect choke thermostat air line at carburetor and at manifold and remove line. Disconnect distributor ventilating line at carburetor air intake elbow7. Loosen hose clamp at carburetor air intake elbow (fig. 62) and lift elbow off carburetor. Make sure both fuel tank control levers (in driver’s compartment) are in “OFF”
CHOKE THERMOSTAT
THERMOSTAT HOUSI MOUNTING SCREWS
THROTTLE ROD
IDLE ADJUSTING
Figure 93. Carburetor adjustments.
183
CRANKCASE AIR CLEANER
AIR INTAKE ELBOW
CARBURETOR CHOKE SHAFT
CARBURETOR
RA PD 331818
Figure 94. Testing choke shaft.
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CRANKCASE VENTILATOR AIR CLEANER
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INTAKE MANIFOLD
THROTTLE ROD
Figure 95. Removing or installing carburetor.
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184
positions. Loosen hose clamp at carburetor auxiliary fuel filter and slide hose off connection. Loosen hose clamp at crankcase breather tube at rear of carburetor and slide hose off nipple. Unhook throttle pull-back spring from throttle rod and slide rod out of throttle shaft. Remove four nuts holding carburetor to intake manifold and remove carburetor and upper gasket (fig. 95). Leave insulator and lower gasket on manifold.
d. Installation. Install a new gasket over insulator on intake manifold. Place carburetor over mounting studs on intake manifold and install four retaining nuts. Slide rubber gasoline hose over connection on carburetor auxiliary filter and tighten hose clamp. Connect crankcase breather hose to fitting at rear of carburetor and tighten hose clamp. Connect choke thermostate air line to carburetor and to exhaust manifold by screwing nut on pipe into fitting on carburetor and manifold. Tighten securely. Slide air intake elbow over top of carburetor and tighten hose clamps securely. Connect air lines to carburetor intake elbow and tighten securely. Slide trunnion on throttle rod through throttle shaft lever, hook pull-back spring to hole in trunnion, and connect spring to bracket on manifold front clamp bolt.
e. Throttle Linkage Adjustment. (1) Run engines until they are thoroughly warm (at least 165° F.) so that choke valves are wide open. Adjust throttle stop screw so that each engine speed is from 450 to 475 revolutions per minute as noted on the tachometer, with the transmission selector lever in DRIVE position and parking brakes set. Insert a ^-inch drill rod through cross shaft relay lever and cross shaft mounting bracket on left engine to set throttles in zero position (fig. 96). If pin does not line up with holes in lever and mounting bracket, turn throttle adjusting nut on end of throttle rod assembly until pin slides through both holes freely. Remove the pin. Pull out hand throttle until engines are turning over approximately 1,000 revolutions per minute. Speed of engines should not vary more than 50 revolutions per minute at idling speed, or 100 revolutions per minute at 1,000 revolutions per minute. Equalize speed of engines by turning throttle rod assembly adjusting nut at end of throttle rod. With engines turned off, pull up on engine cross shaft to rear relay rod as far as possible to set throttle in wide-open position, and be sure that throttle valves are wide open.
(2) Working in driving compartment, push down on accelerator pedal (with engines not running) until throttles are in wide-open position, and measure distance between accelerator pedal and front hull plate. This distance should be one-eighth inch with throttle linkage in full-open position. If clearance is incorrect, disconnect rod from pedal cross shaft lever to front throttle relay and turn clevis until i^-inch clearance is secured. Reconnect rod and tighten lock nut.
185
Engage auxiliary accelerator and adjust pedal in same manner. Adjust hand throttle by turning adjusting nuts on end of hand-throttle cable until nuts are one-eighth inch from trunnion with throttle linkage in closed position. Be sure of freedom between trunnion and handthrottle-cable extension. Bend mounting bracket, if necessary, to line up cable with trunnion.
f. Servicing Auxiliary Fuel Filter. Loosen bail nut and remove bowl from filter. Do not try to remove gasket as it may be cemented in place. Wash filter element with dry-cleaning solvent.
Caution: Do not damage the disks. Do not scrape or scrub or use compressed air. Do not disassemble the filter element. If element cannot be cleaned satisfactorily, replace entire element assembly. Wash fuel bowl before reinstalling. Install fuel bowl on filter, making sure that gasket is in place and tighten bail nut. Nut should be tightened finger-tight. If bail nut is overtightened, the gasket may be cut by the fuel bowl or the bail stretched to the point where a good seal between the bowl and the filter body cannot be obtained. In the event the bail has been stretched, it may be kinked slightly to allow the bail nut to contact the bowl. Check for leak when engines are running.
111. Fuel Pumps
a. Description. An electric fuel pump is mounted at the bottom of each fuel tank in a screened cage at the lower end of the fuel-pump support assembly. This pump consists of a small electric motor which
CROSS SHAFT SUPPORT
GAGE PIN HOLE
THROTTLE ROD
1/4-INCH PIN
RA PD 331807
Figure 96. Inserting gage pin for throttle cross shaft.
186
rotates a centrifugal-type impeller (fig. 97). The entire pump assembly operates submerged in gasoline.
Z>. Removal. Fuel pumps normally require no attention in service. To replace an inoperative pump, remove the support assembly by first turning master switches to the “OFF” position, and then removing fuel-tank-cover plate by removing the attaching screws and lifting off plate (fig. 99). Remove screw which holds pump feed wire to terminal and tape end of wire. Loosen hose clamp at fuel-outlet
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Figure 97. Electric fuel pump.
FUEL PUMP TERMINAL
FUEL CHECK VALVE
UPPER STRAINER AND FLAME ARRESTOR
FUEL PUMP FEED CONDUIT
LOWER STRAINER
— FUEL FILLER CAP
FUEL FILLER
FUEL LINE
CAGE FOR FUEL PUMP
RAPD 331347
Figure 98. Fuel-pump-support assembly.
187
elbow and slide hose off nipple. Remove 12 attaching screws and remove complete support assembly (fig. 98). Remove four screws holding cover to bottom of cage and remove cover. Loosen hose clamp at fuel pump discharge port nipple. Remove four cotter pins and mounting cushions, and lower pump in mounting cage. Loosen set screw at electrical-feed cable at top of fuel pump and unscrew feedcable connection. Remove fuel pump from cage.
c. Installation. Connect electrical-feed cable to top of fuel pump and Jock in place with set screw. Raise pump in mounting cage and, at the same time, insert discharge-port nipple into hose. Install mounting cushions and four new cotter pins, and tighten hose clamp securely. If cage-cover seal has been removed, install seal against upper cage flange. Place cover on bottom of cage and install four attaching screws. Position a new gasket on fuel tank and slide support assembly into fuel tank and into retainer in bottom of tank. Install 12 attaching screws, mounting ground strap under one screw and tightening all screws securely. Connect fuel line hose connection to nipple and tighten hose clamp (fig. 99). Remove tape from end of feed wire and install on terminal. Place rubber guard over terminal. Position fuel tank cover over opening and install attaching screws.
112. Fuel Tanks and Lines
a. Description. Two fuel tanks, of approximately 55 gallons each, are carried in narrow, deep compartments on each side of the engine compartment. Each tank contains a cover and pump support assembly on which are mounted all of the parts normally requiring service.
6. Draining. A drain-hole cover is secured to the hull floor directly under each fuel tank (fig. 26). To drain the tank, remove the four cap screws holding the plate in position, and remove the drain plug at the bottom of the tank.
c. Removal. Unlatch battery compartment covers and lift off covers. Remove covers over fuel tanks by removing the attaching screws and lifting off covers. Turn master battery switch to OFF position. Disconnect fuel pump feed wire at terminal and tape wire. Disconnect terminals at battery. Remove two battery hold-down nuts (fig. 80). Remove hold-down and lift out battery. Remove battery box retaining screws and lift out battery box. Remove screw holding ground strap to top of fuel pump support assembly. Remove screws holding conduit clamps to fuel tank cover angles and lay conduit to one side. Loosen hose clamp at fuel pump assembly outlet and slide hose off connection. Remove two screws holding shut-off valve assembly to side of hull; disconnect fuel line at shut-off valve by loosening hose clamp and slide hose off connection. Lay conduit and shut-
188
off valve assembly to one side. Remove screws holding compartment cover angles to hull and remove angles. Remove screws holding flat spring spacers to insulating pad on inner wall of compartment and pull out spring spacers. Attach a rope sling through lifting handles on fuel tank and remove tank from compartment.
d. Installation. Lower fuel tank into compartment. Install three flat spring spacers between tank and inner compartment, sliding into groove provided. Install retaining screws. Position fuel tank compartment angles around opening, making sure that the seals are in proper position, and install angle attaching screws. Install battery box. Lower battery in battery box and install hold-downs. Connect terminals to battery (fig. 80). Place shut-off valve assembly against inner compartment wall and install two attaching screws. Reconnect fuel line to shut-off valve and nipple on fuel pump support assembly and tighten hose clamps. Install three screws and clamps holding conduit to inner fuel compartment angle. Connect ground strap to top of fuel pump support assembly, and reconnect feed wire to terminal. Install rubber guard over terminal. Position fuel tank cover and battery cover over openings and install attaching screws.
e. Replacement of Lines. (1) The main fuel line extends from one fuel tank to the other, and is carried across the support at the front of the engine compartment (fig. 91). This line contains two T connections from which a rubber line extends to an auxiliary filter at the carburetor float chambers. The fuel lines are connected to the T’s for the carburetor by short hose connections. These connections are of a neoprene composition, and should not be replaced with ordinary rubber hose.
(2 ) When removing the fuel line, be sure fuel control levers are in the OFF position. Remove fuel tank cover. Disconnect the fuel line at the shut-off valve at the side of the engine compartment by loosening hose clamps and sliding hose off pipe. Disconnect fuel hose at each carburetor auxiliary filter by loosening hose clamp and sliding hose off nipple. Remove four bolts and clamps holding main line to the support bar and lift the fuel line as an assembly out of vehicle.
(3 ) To reinstall the fuel line, position the assembly against the support bar and install the four bolts and clamps holding main line to bar. Slide fuel hose over nipple at carburetor auxiliary filter and tighten hose clamp. Reconnect fuel line at shut-off valve and tighten hose clamp. Start both engines and run for a sufficient length of time to check all connections for leaks. Install fuel tank covers. Close engine compartment.
113. Exhaust Pipes and Mufflers
a. General. The exhaust system, consisting of the exhaust manifolds, manifold connections, mufflers, and exhaust pipes can be re-
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CONDUIT TO TAILLIGHT FIRE EXTINGUISHER DISCHARGE NOZZLE SHUT-OFF VALVE FUEL LINE TO CARBURETORS J FUEL TANK ? FUEL PUMP SUPPORT SCREWS (12) FUEL LINE TO VALVE I VALVE CONTROL CABLE
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190
moved with the engines in the vehicle. The removal of the exhaust manifolds and manifold connection is covered in paragraph 65.
5. Removal. (1) Open engine compartment door. Turn door latches and raise doors.
(2) Remove engine compartment doors and covers. Refer to paragraph 67.
(3) Remove muffler assembly. Remove bolt and lock washer attaching exhaust pipe extension to exhaust pipe outlet elbow. Remove bolt at rear of exhaust pipe extension on extension shield and slide extension towards rear enough to clear outlet elbow (fig. 60). Remove screw and nut attaching muffler outlet pipe support bracket to muffler inlet pipe assembly. Loosen two nuts at outlet pipe clamp at muffler, work outlet pipe free of muffler, and remove from vehicle. Remove two bolts and nuts holding muffler and inlet pipe assembly to exhaust manifold connection pipe (fig. 61), and remove muffler. Discard used gasket.
(4) Remove exhaust manifolds. Refer to paragraph 65.
c. Installation. (1) Install exhaust manifolds. Refer to paragraph 65.
(2) Install muffler. Lower muffler and inlet pipe assembly into position in vehicle. Place a new gasket between the exhaust connection flange and muffler inlet assembly. Install two bolts and nuts holding muffler inlet assembly to exhaust connection flange. Insert end of muffler and outlet pipe into muffler and position clamp around pipe and muffler. Install screw and nut which attach outlet pipe support bracket to muffler inlet pipe assembly.
Note. Do not tighten bolts at muffler clamp or at support bracket until exhaust pipe extension is temporarily installed for alinement of rear support bolt.
Tighten bolts at muffler and support and remove exhaust pipe extension.
(3) Install engine compartment covers. Refer to paragraph 685 (18).
(4) Install exhaust pipe extension. Slide exhaust pipe extension through extension shield and into muffler outlet elbow (fig. 60). Install attaching screw at outlet elbow. Install exhaust pipe extension rear support bolt at extension shield and tighten securely (fig. 60).
(5) Install engine compartment doors. Refer to paragraph 685 (20).
Section XXVI. COOLING SYSTEM
114. Description and Data
a. Description. (1) The vehicle is equipped with two identical, but completely independent cooling systems, one for each engine and transmission (fig. 100). Each system contains the following major
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units: radiator, water pump, thermostat and necessary connections, engine fan and fan drive, and oil cooler for the hydramatic transmission.
(2) The coolant is drawn from the radiator by the water pump and forced into the engine water jackets. After circulating through both cylinder blocks and cylinder heads, the heated coolant is forced up through hose connections to the upper tank of the radiator. A blocking-type bimetal thermostat with double poppet valves, located in the radiator inlet housing, permits free flow when the coolant is hot. However, it causes cold fluid to recirculate through a bypass hose back to the water pump and through the engine until the engine reaches an efficient operating temperature.
(3) Cooling fluid is also pumped through an external pipe to an oil cooler located in the transmission oil pan, where it cools the transmission oil and is returned to the water pump.
(4) The capacity of each cooling system is 40 quarts.
(5) The engine fan is carried in a mounting spider attached to the fan shroud at rear of radiator. The fan is driven by a drive shaft mounted on ball bearings under the intake manifold, and through a universal joint and yoke connected to the generator pulley.
b. Tabulated Data. (1) Fan.
Blades, angle__________________________
Blades, diameter_______________________
Blades, number of----------------------
Drive__________________________________
Drive ratio____________________________
32°.
21 inch.
4.
Belts, drive shaft and universal joints.
1.1 to 1
Make________________
(2) Radiator.
Core area (each)____
Type----------------
Make________________
(3) Thermostat.
Location___________
Opening temperature.
Type----------------
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540.5 square inches.
. Tube-and-fin.
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Radiator inlet housing.
. 140° to 146° F.
Bimetal.
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(4) Water pump.
Drive_____________________________________Triple belt.
Lubrication_______________________________Fitting.
Packings__________________________________ Spring-loaded, chevron-
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Type______________________________________Centrifugal.
Location__________________________________Right front of engine
block.
193
115. Maintenance
a. Adding Coolant. (1) Vent filler cap before removing. Whenever removing the filler cap from a hot system, always vent the radiator long enough to allow all pressure in the system to escape; otherwise, there is a possibility of serious personal injury from steam and hot water. To vent the radiator, turn the cap to the left (counterclockwise) until the first stop is reached (fig. 101). Leave the cap in this position at least one-half minute, or long enough to vent the system thoroughly. Then press down on the cap to clear the stop, and then turn it further to the left to remove.
(2) Install cap securely. After bringing the fluid to the proper level (2 inches below filler neck), reinstall the radiator cap, and be sure to turn it as far as possible by hand so that the entire cooling system will be sealed while operating. If this is not done, there may be excessive loss of coolant while operating under severe service.
Note. Make sure radiator cap gasket is in good condition and in place before installing cap.
b. Draining and Filling. (1) Drain system. Each cooling system is drained at one point only, a plug marked “WATER,” in the bottom of the transmission oil pan (fig. 27). Remove radiator cap to vent system for rapid and complete draining.
(2) Install coolant. Add water or antifreeze as required, pouring at moderate speeds to avoid undue spillage. It may be necessary to run the engine for a few minutes before the thermostat opens and permits complete filling of the system. Be sure to perform this operation if the system seems full before 40 quarts have been added.
LOCKING PIN FOR COVER
DIRECTION FOR REMOVAL ' DIRECTION FOR SEALING
Figure 101. Removing radiator cap.
194
c. Cleaning. (1) Flushing. Open the petcocks which shut off the coolant from the heaters or other accessories, if used, to allow for complete circulation during the cleaning, flushing, and draining. Run the engine, with the air inlet covered if necessary, until the temperature is within operating range. Stop the engine, remove the radiator cap, and drain the system by opening the drain plug in the transmission oil pan (fig. 27).
(2) Allow the engine to cool. Close the drain plug, pour water slowly into the radiator until the system is approximately half full, then run the engine at idling speed. Add cleaning compound in the proportion of one container of cleaner to every 4 gallons of cooling system capacity. Then complete filling the system with water.
Caution: Never mix the water and the cleaning compound before putting them into the system. Do not spill the solution on skin, clothing, or painted portions of the vehicle.
(3) Install radiator cap and run engine at fast idling speed, covering air inlet if necessary, until coolant reaches a temperature above 180° F. but not over 200° F. Do not drive the vehicle.
(4) Stop the engine after it has run for 30 minutes at 180° F. but not over 200° F. Then remove drain plug and radiator cap and drain system completely.
(5) For information on back-flushing of engines, refer to TM 9-2858.
d. Neutralizing. (1) Allow engine to cool. Install drain plug, pour water slowly into the radiator until the system is approximately half full (20 quarts), then run engine at idling speed. Add neutralizer compound in the proportion of one container of neutralizer to every 4 gallons of cooling system capacity. Each cleaning compound container contains a separate portion of neutralizer. Then fill system with water.
(2) With air inlet covered, let engine idle for at least 5 minutes at normal operating temperature. Then stop engine.
(3) Drain system completely by removing drain plug and radiator cap.
e. Flushing. (1) Allow engine to cool. Install drain plug. Pour water slowly into radiator until system is approximately half full, then run engine at idling speed and fill system completely.
(2) Run engine, keeping air inlet covered if-necessary, until coolant is heated to normal operating temperature.
(3) Drain system by removing drain plug and radiator cap. Repeat flushing operation until drain water is clear.
(4) Again allow engine to cool and clean all sediment from radiator cap valves and overflow pipe. Blow insects and dirt from radiator core air passages with compressed air, blowing from the rear. Use water if necessary to soften obstructions.
195
f. Leaks. After completing the flushing operation, make certain that engine has been allowed to cool again. Install drain plug. Pour water slowly into radiator until system is approximately half full, then run engine at idling speed and fill system to 2 inches below bottom of filler neck. Stop engine. Examine entire cooling system for leaks. This is important because the cleaning solution uncovers leaks which exist but are plugged with rust or scale. Leaks that cannot be corrected by the using arms should be reported immediately to ordnance maintenance personnel. After leaks have been remedied perform g below.
g. Coolant Service. (1) When servicing the vehicle for summer, fill the system nearly full with clean water. Add corrosion-inhibitor compound in the proportion of one container of inhibitor to each 4 gallons of cooling system capacity. Then complete filling the system with water.
(2) When servicing for winter, fill the system about one-third full of clean water. Add sufficient antifreeze compound (ethylene-glycol type) for protection against the lowest anticipated temperature. Refer to paragraph 23. Add water until system is nearly full, then run engine until normal operating temperature is reached. Then add sufficient water to fill system to 2 inches below bottom of filler neck.
116. Hoses and Connections
a. Removal. Drain cooling system (par. 115Z>). Loosen screws in hose clamps and slide hose off ends of radiator, cylinder head and water pump elbows, and bypass fittings.
b. Installation. The hoses are installed without gasket paste or sealer. Install clamps on hoses, slide in place on connection elbows and fittings, and tighten clamp screws securely.
117. Radiator Thermostat
a. Removal. Drain approximately 2 gallons of fluid from cooling system and reinstall drain plug. Open engine compartment door. Loosen hose clamps and disconnect the two hoses at radiator inlet housing on top tank. Remove four cap screws and washers holding inlet housing to radiator, and remove housing. Remove thermostat and discard gasket (fig. 102).
b. Inspection. Check thermostat by placing it with bimetal coil down on a brick in a pan of water also containing a thermometer.
Caution: Do not place either the thermostat or the thermometer on bottom of pan because of uneven concentration of heat at that point when pan is heated over a burner.
Heat water until thermostat valve begins to open. The temperature at which this occurs depends on the heat range which the thermostat is designed for. See tabulated data, paragraph 114. The oper-
196
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Figure 103. installing radiator thermostat.
ating temperature is stamped on the housing flange of most thermostats. If the thermostat does not open, or does not open at a temperature close to the markings found on the thermostat flange, it should be replaced. If the thermostat does not open and close completely and function freely, or is badly rusted, it should also be replaced.
197
CROSS ANGLE—1 RADIATOR INLET HOUSING^ ^~RAD|ATOR TQp TANK
RAPD 331383
Figure 102. Radiator thermostat housing.
RADIATOR INLET
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Figure 106. Removing radiator.
c. Installation. Place a new housing gasket on radiator tank, and position thermostat on gasket with valve extending into radiator tank with axis of valve horizontal (fig. 103). Position housing, and install four mounting screws and washers. Using a torque wrench, tighten cap screws to 18 foot-pounds. Reconnect hose to housing and tighten hose clamps. Fill cooling system and close engine compartment door.
118. Radiator and Fan
a. Removal. (1) Drain cooling system. Refer to paragraph 1156.
(2) Remove radiator air inlet and engine compartment doors. Remove two bolts attaching angle plate at rear of engine compartment doors and remove angle plate and doors. Remove five screws holding radiator air inlet assembly to hull roof, and six screws that hold inlet to engine compartment cross angle (fig. 104). Hook sling to inlet assembly, attach hoist to sling, and lift radiator inlet assembly off vehicle.
199
(3) Remove radiator. Disconnect radiator overflow pipes at hose connection at filler neck and under metal seal at engine compartment sides, and remove pipes (fig. 105). Remove five screws that hold metal seal to radiator cross angle and remove seal. Loosen hose clamps on radiator inlet housing at top of radiator and outlet pipe at bottom of radiator, and pull hose off connections. Remove four cap screws holding fan shaft universal joint bearing trunnions on fan shaft yoke. Slide slip joint back to clear fan shaft yoke. Remove two long bolts that hold upper part of radiator to center and side supports. Back out one long bolt holding lower part of radiator to side support.
Note. This bolt cannot be removed completely until radiator has been lifted out.
Working on rear side of radiator, remove short bolt that holds radiator to support at center. Hook sling (41-S-3832-82) to lifting rings on top of radiator; connect hoist to sling and lift radiator, shroud and fan assembly out of vehicle (fig. 106). Tilt radiator forward to clear cross angle with fan shaft yoke. Remove other radiator in same manner. Remove eight bolts and washers attaching fan spider to fan shroud and remove fan. Remove four bolts, nuts, and washers attaching fan shroud to radiator and remove shroud.
b. Installation. (1) Install radiator. Place fan shroud on radiator and install four attaching bolts, nuts, and washers. Place fan assembly on fan shroud and install eight bolts and washers attaching fan spider to shroud. Connect sling (41-S-3832-82) to radiator lifting rings, attach hoist to sling, slide long lower outer bolt in position, and lower radiator in position in engine compartment. Tilt top of radiator toward rear of vehicle to clear cross angle with fan shaft (fig. 106). Install one long bolt through upper part of radiator and into tapping nut on center support. Screw long lower outer bolt into side support. Working at rear of radiator, install short bolt through center support and into tapping nut on radiator. Reconnect hose connections at radiator inlet housing at top of radiator and outlet housing at bottom of radiator, and tighten hose clamps. Line up fan shaft yoke with universal joint bearing trunnions and install four cap screws and lock plates. Tighten cap screw to a torque tightness of 16 to 20 foot-pounds and lock in place by bending lock plate ears over flat of cap screw. Position metal seal on radiator cross angle and radiator, and install five mounting screws with washers (fig. 105). Place radiator overflow pipe on top of radiator, connect short hose at filled neck and hose under metal seal at engine compartment side to pipe, and tighten hose clamps. Install overflow pipe clip screw.
(2 ) Install radiator air inlet and engine compartment doors. Hook sling on air inlet assembly, attach hoist to sling, and lift inlet assembly into position on vehicle. Install bolts through radiator inlet front flange and into hull roof. Do not tighten bolts. Line up six holes
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in rear of radiator inlet with bolt holes in radiator cross angle, and install six bolts. Position two engine compartment doors over opening and install angle plate and two bolts. Tighten bolts after lining up engine compartment door and radiator inlet on hull.
(3 ) Refill cooling system. Refer to paragraph 115.
119. WaterPump
a. Removal. Drain cooling system (par. 115&). Reinstall drain plug. Open engine compartment doors. Remove four bolts attaching generator access plate at rear of engine compartment (fig. 59) and remove plate. Loosen locking nut holding generator cradle in position, and lower generator to lowest position. Slip belts off water pump pulley by hand. Loosen hose clamp that holds hose on pump body inlet. Remove five screws and washers that hold water pump body to cylinder block, and remove pump and discard gasket (fig. 107).
b. Installation. Place new gasket on water pump, and position pump on cylinder block with pulley under generator and water pump belts. Install five pump mounting screws and lock washers, and draw up evenly (fig. 107). Reconnect pump inlet hose and tighten hose clamps. Reinstall belts on water pump pulley, prying in place by hand only. Using large screwdriver or small utility bar between generator and generator cradle, pry up on generator and adjust belts until there is from %- to %-inch deflection in belts measured midway
CRANKCASE EN-BLOC ,
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Z WATER INLET CONNECTION HOSE L WATER PUMP RA PD 331300
Figure 107. Water pump mounting.
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between generator and water pump pulleys (fig. 50). Hold generator in this position and tighten generator cradle locking nut. Replace access plate at rear of engine compartment. Close engine compartment doors. Refill cooling system.
ENGINE CONDUIT-/ FRONT BAND INDICATING
\SLr°D CAP-7 wk / FRONT BAND ADJUSTING / / screw
/, / / ENGINE front support -
/ x VACUUM LINE
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OIL COOLER WATER-/ k LEVER
INLET LINE WARNING OIL PAN-3 SIDE COVER
SIGNAL SWITCH RA PD 331305
Figure 108. Hydramatic transmission.
FULCRUM LEVER CLEVIS PIN BRACKET
FULCRUM
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ADJUSTABLE ROD REAR RELAY LEVER
RA PD 331304
Figure 109. Adjusting transmission control linkage.
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Section XXVII. HYDRAMATIC TRANSMISSIONS
120. Description and Data
a. Description. The hydramatic transmission (fig. 108) consists of a fluid coupling and an automatic hydraulic-operated transmission having four speeds forward. No reverse gearing is incorporated in the transmissions as this is provided in the transfer unit. Slippage in the fluid coupling at engine idling speeds eliminates the need for a clutch. Gear changes are made automatically by hydraulic pressure, and are governed by the speed of the vehicle and the extent to which the driver depresses the accelerator. In this section, the fluid coupling end of the transmission will be referred to as the “front” end, and the output shaft end as the “rear” end.
b. Data.
Clutch type------------------------------------Fluid coupling.
Number of speeds_______________________________ 4.
First speed gear ratio_________________________3.92 to 1.
Second speed gear ratio________________________ 2.53 to 1.
Third speed gear ratio_________________________1.55 to 1.
Fourth speed gear ratio________________________1 to 1.
Type gearing-----------------------------------Planetary.
121. Manual Control Linkage Adjustment
a. General. The transmission manual control linkage from the neutral pedal in the driving compartment to the cross shaft under the bulkhead is set at assembly of the vehicle, and normally requires no further adjustment. If engines are replaced, or it becomes necessary to synchronize transmission control linkage, adjustment should be made at the fulcrum lever mounting bracket on the transmission rear bearing support (fig. 109) as outlined below.
b. Adjustment Procedure. Place transmission selector lever in “DRIVE” slot of quadrant (fig. 9). Open door in bulkhead extension cover over transfer unit. Working through opening, loosen clamp .screw on fulcrum lever adjusting rod (fig. 109). Move fulcrum lever and attached levers to the middle detent position. Holding adjusting rod in position, tighten clamp screw. Adjust other transmission linkage in same manner.
c. Check Adjustment of Both Transmissions. Set brakes. Run both engines at same time with transfer unit in HIGH and transmission selector lever in NEUTRAL. Set hand throttle to run engines at 1,000 revolutions per minute, and move selector lever slowly toward DRIVE. By watching tachometers, note position of lever when speed of one engine drops. Rear edge of selector lever should be approximately one-eighth inch in front of front edge of slot in quadrant when
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engine speed drops. Continue moving lever until speed of other engine drops. This should be within T/s-inch additional lever travel. If difference is greater, readjust fulcrum lever of newly installed transmission.
122. Band Adjustment
a. General. The transmission front band is provided with an adjustment-indicating rod (fig. 110) and can be adjusted in the vehicle. The rear band is provided with an automatic band adjuster and does not incorporate an indicating rod. If tests indicate that the rear band requires adjusting, notify ordnance personnel.
b. Adjustment Procedure. Remove 18 mounting screws and remove hull rear floor cover under engine and transmission to be checked. Set vehicle brakes, place transmission selector lever in NEUTRAL and start engine.
Note. Transmission should, if possible, be at normal operating temperature before making band adjustments.
Working through the engine compartment floor opening, remove transmission band indicating rod cap (fig. 108). Run engine for a few minutes at idling speed; then move transmission selector lever to DRIVE position and set hand throttle so that engine is running at approximately 1,000 revolutions per minute. Hold a straightedge or
INDICATING ROD CAP
FRONT BAND ADJUSTING SCREW
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LOCK NUT
RAPD 331797
Figure 110. Front band adjustment.
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scale across front band indicating rod boss, and check to see if indicating rod end is flush with rod boss on transmission case. Band is correctly adjusted when indicating rod end is flush with rod boss on transmission case (fig. 110). If band adjustment is incorrect, move lever back to NEUTRAL, loosen band adjusting screw lock nut and turn front band adjusting screw to estimated correct adjustment, move lever again to DRIVE, and recheck. Repeat until indicating rod end is flush with rod boss. Idle the engine. Lock band adjusting screw and recheck adjustment. Install indicating rod cap, being sure seal is in place.
Caution: Run one engine only, and do not pull the engine against the fluid coupling for more than 1 minute at a time, and allow at least 3 minutes for the oil to cool before repeating.
123. Transmission Replacement
a. Authority. Replacement of this major assembly with a new or rebuilt unit is normally a field maintenance operation, but may be performed in an emergency by organizational maintenance units, provided authority for performing this replacement is obtained from the appropriate commander. Tools needed for the operation which are not carried in organizational maintenance units may be obtained from a higher maintenance unit.
b. Removal. (1) Remove engine. Remove engine and transmission assembly (par. 67).
(2) Remove lower flywheel housing. Remove six screws that hold lower flywheel housing to upper housing; remove housing and discard gasket.
(3) Remove starter motor. Disconnect solenoid at terminal on solenoid relay. Remove two mounting bolts holding starter to flywheel housing and remove starter.
(4) Remove lines and leads. Disconnect right and left oil cooler lines at transmission oil pan fittings (fig. 108); loosen upper connections at crankcase and water pump inlet pipe; and move lines out of the way. Loosen hose clamp on hose connecting transmission and engine oil filler tubes at transmission filler side. Remove screw that holds transmission filler tube lower mounting to transmission case. Remove nut holding filler tube upper mounting bracket to rear manifold clamp stud, and remove tube. Disconnect vacuum line at fitting on intake manifold and elbow on transmission case (fig. 108). Remove flywheel housing mounting screw holding vacuum line clips, and remove line. Disconnect warning signal switch wire at switch on transmission, and pull conduit out of clip on transmission side cover.
(5) Drain transmission. Install socket wrench on engine crankshaft pulley mounting screw and turn crankshaft until flywheel cover drain plug is at the bottom. Remove drain plug in flywheel cover and
752022 0—47-----14
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in transmission oil pan (fig. 27) and drain transmission. Reinstall drain plugs.
(6) Remove transmission. Install lifting eye (41-B-1586-300) in top of transmission case. Connect hoist to eye and take up weight of transmission. Remove 30 screws that hold flywheel cover to flywheel.
Note. Rotate crankshaft with socket wrench on engine crankshaft pulley mounting screw.
Remove remaining six screws that hold flywheel housing to crankcase and pull engine conduit out of the way. Pull transmission back to slide flywheel housing off dowels in crankcase, and mainshaft pilot out of bearing in end of crankshaft, and remove transmission.
c. Installation. (1) Install transmission. Position new fly wheel cover gasket on flywheel.
Caution: Do not use gasket sealer of any kind.
Install lifting eye (41-B-1586-300) in transmission case, attach hoist to eye, and lift transmission into position behind engine crankcase. Push transmission toward engine, entering dowels in crankcase in holes in flywheel housing and mainshaft pilot in bearing in end of crankshaft. Install six flywheel housing mounting screws, placing clips for engine conduit and vacuum pipe clip under upper screws. Tighten screws to 45 to 50 foot-pounds, using torque wrench and tightening lower screws first.
(2) Install flywheel cover. Pull flywheel cover toward flywheel and line up dowels in flywheel with holes in cover. Hold cover in position and install one mounting screw adjacent to dowels. Turn flywheel 180° (using socket wrench on crankshaft pulley mounting screw) and install another screw. Tighten these two screws to 12 to 15 foot-pounds, making sure that cover seats properly on flywheel and flywheel dowels. Install two screws approximately 90° to dowels and tighten to 12 to 15 foot-pounds. Install remaining 26 screws and tighten all screws to 25 to 30 foot-pounds, using a torque wrench. Then tighten all screws to 40 to 45 foot-pounds, proceeding in rotation around the flywheel. Disconnect hoist and remove lifting eye.
(3) Install starter motor. Lift starter into position on flywheel housing, and install two mounting screws through housing and into starter mounting flange. Connect solenoid wire to terminal on solenoid relay.
(4) Connect lines and leads. Connect transmission warning signal switch wire to switch, and push conduit into clip on transmission side cover. Connect vacuum line to intake manifold and to elbow on transmission case. Position filler pipe in transmission case and push upper side outlet into hose connection on engine oil filter tube and upper mounting bracket over engine manifold rear stud. Install screw through lower filler tube mounting bracket and into transmission case. Install nut holding upper tube bracket to manifold stud, and tighten 206
hose clamp on transmission to engine filler tube hose. Connect oil cooler lines to fittings on transmission oil pan and tighten upper and lower connections.
(5) Install lower flywheel housing. Install new gasket on lower flywheel housing and lift into position on upper flywheel housing and install six mounting screws.
(6) Install engine. Install engine and transmission assembly in vehicle (par. 68).
(7) Refill transmission. Install 10 quarts of engine oil. Start engine and run for approximately 5 minutes to fill fluid coupling (fig. 28) ; then add an additional 5 quarts to bring oil up to FULL mark on gage. Make certain the engine is stopped before adding the last 5 quarts.
124. Torus Member Replacement
a. Authority. Replacement of this major assembly with a new or rebuilt unit is normally a third echelon operation, but may be performed in an emergency by second echelon, provided authority for performing this replacement is obtained from the appropriate commander. Tools needed for the operation which are not carried in second echelon may be obtained from a higher echelon of maintenance.
b. Removal. (1) Remove engine. Remove engine and transmission assembly from vehicle (par. 67).
(2) Remove transmission. Remove transmission assembly from engine (par. 123a).
(3) Remove torus members. Straighten mainshaft nut lock, and remove nut and lock holding driven torus member on shaft. Pull
SNAP RING
MAIN SHAFT
DRIVING TORUS
FLYWHEEL COVER
SNAP RING PLIERS
INTERMEDIATE
SHAFT
UPPER FLYWHEEL HOUSING
RA PD 353815
Figure 111. Removing driving torus snap ring.
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VACUUM PIPE CONNECTOR GOVERNOR PIPES GOVERNOR SLEEVE
Figure 112. Removing transmission valve body.
driven torus member off mainshaft. Remove snap ring holding driving torus on intermediate shaft, using snap ring pliers (41-P-1992-85) (fig. 111). Pull out on driving torus and remove from intermediate shaft.
c. Installation. (1) Install torus members. Push driving torus on splines of intermediate shaft and install snap ring (fig. Ill), using snap ring pliers (41-P-1992-85). Push driven torus on transmission mainshaft splines, and see that oil pressure regulator on inner hub slides over end of intermediate shaft. Install driven torus retaining nut and new lock on mainshaft and bend lock back over nut.
(2) Install transmission. Install transmission assembly on engine (par. 123Z>).
(3) Install engine. Install engine and transmission assembly in vehicles (par. 68).
125. Valve Body
a. Removal. (1) Remove center hull floor cover. Remove screws from hull floor cover under transmission.
Caution: Support rear end of cover while removing last screws to prevent cover from dropping down and causing injury.
Front of cover is held up by hooks on cover. Slide cover toward rear of vehicle and lower to ground.
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VALVE BODY -^^^ANUA^ONTROL ROD VACUUM PIPE ElftQW
(2) Remove side cover. Working through the floor opening, remove hairpin lock and clevis pin that hold manual control fulcrum lever to adjustable mounting bracket on rear bearing support (fig. 109). Then lower lever out of the way.
Note. Do not disconnect fulcrum lever at lower end.
Remove the two cap screws that hold the lever mounting bracket to the transmission, and remove the bracket by pulling it straight out to clear the two locating dowel pins. Pull warning signal switch conduit out of retaining clip on side cover. Disconnect lead wire on warning signal switch and remove signal switch. Pull rubber boot off end of manual control rod, and back rod bearing nut out of cover. Remove 11 screws that hold side cover to transmission case (fig. 108), move cover out at engine end to clear valve body, and then pull toward front of vehicle to clear manual control rod end and remove cover.
Caution: When removing side cover, be very careful to prevent any dirt from falling into transmission through case openings.
(3) Remove valve body. Disconnect control valve vacuum pipe at valve body and elbow on transmission case and remove pipe. Remove four control valve body mounting screws and pull valve body assembly toward engine to move oil tubes out of governor sleeve, and remove assembly (fig. 112).
Note. The only organizational maintenance operation authorized on the valve body is removal and installation.
An improperly operating valve body should be reported to ordnance personnel.
b. Installation. (1) Install valve body. Make sure valve body mounting surface on transmission case and valve body are free of nicks and burs, and thoroughly clean. See that three oil pipes are in position in valve body (fig. 112), and place valve body in position on transmission case, entering the three oil pipes into governor sleeve. Hold in position and install four mounting screws, tightening evenly to 6 to 8 foot-pounds, using a torque wrench. Position vacuum pipe on valve body and transmission case fittings and connect.
(2) Install side cover. Be sure governor plug is in place in governor sleeve. Position a new side cover gasket on transmission case.
Caution: Do not use gasket sealer of any kind.
Place side cover in position by holding valve body end of cover away from transmission, and sliding opposite end of cover over manual control rod. Then move cover toward engine block and over valve body. Install 11 cover mounting screws and copper washers. Slide control rod bushing nut over rod, tighten into side cover, and install rubber boot over rod, seeing that outer end of grommet seats in groove in rod. Reinstall warning signal switch. Push conduit into clip on side cover and connect lead wire to switch terminal. Reinstall fulcrum
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lever mounting bracket to transmission, making sure holes in bracket line up with locating dowels on transmission. Install two attaching screws and tighten securely.
(3) Adjust manual control linkage. Connect and adjust linkage at fulcrum lever mounting bracket (par. 1226).
(4) Install full floor cover. Coat edges of floor plate with joint and thread compound (cement, type II) and place gasket on plate. Raise front edge of plate until hooks on plate rest on hull floor. Raise rear end of plate, and line up screw holes with drift punch. Install floor plate retaining screws.
Section XXVIII. PROPELLER SHAFTS AND SUPPORT BEARINGS
126. Description and Data
a. Construction. There are three propeller shafts used in this vehicle. The main propeller shaft extends from the transfer unit forward to the controlled differential. Two final drive propeller shafts extend from the controlled differential, one on each side, to the final drives. The main propeller shaft is of welded steel tube construction. The final drive shafts are made of two forged yokes welded together.
b. Main Propeller Shaft. The main propeller shaft is provided with a yoke for the universal joints welded to each end. The rear universal joint yoke is splined to provide a sliding joint with the
TRANSMISSION SELECTOR LEVER
BULKHEAD EXTENSION FELT TRANSFER UNIT SEAL AND RETAINERS SHIFT LEVER
TRANSFER UNIT SHIFTER MAIN PROPELLER SHAFT CONTROLLED DIFFERENTIAL
SHAFT EXTENSION (SHIELDS REMOVED) RA PD 331821
Figure 113. Main propeller shaft.
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transfer unit mainshaft, and the front yoke is splined to fit on the differential pinion shaft.
c. Final Drive Propeller Shafts. The final drive propeller shaft consists of two forged yokes welded together. The yokes on each side of the controlled differential are splined to the output shafts, and are a slip fit to compensate for movement of the unit and to provide clearance when removing the shafts. The yokes on the final drive input shafts are also splined, but are held on the shafts by a large nut and cotter pin.
d. Tunnel and Guard. The main propeller shaft is mounted in a tunnel formed by metal shields on each side, supported by brackets attached to the hull floor and sealed at the rear by a baffle bolted to the hull floor and bulkhead extension. The top of the propeller shaft tunnel is covered by the periscope stowage box. The final drive propeller shafts are protected by sheet metal shields which fit around the shafts and universal joints, and are bolted together at mounting brackets on the controlled differential and final drive cases. Leg guards are mounted on the final drive housings. All guards are easily removable for service work.
e. Transmission—Transfer Unit. The connection between each transmission and the transfer unit is made by two universal joints and a coupling block. The transmission output shaft carries the rearmost yoke, and the foremost yoke is a sliding spline fit into the short transfer unit input shaft.
/. Data.
Propeller shafts, number used___3
Propeller shafts, type---------- Welded tube and welded forgings.
Universal joints, number used___10.
Universal joints, type__________ Needle bearing.
Universal joints, make__________ Mechanic’s.
127. Main Propeller Shaft
a. Removal. (1) Remove periscope stowage box. Remove four cap screws holding periscope stowage box to support bracket and lift box from its position.
(2) Remove left propeller shaft guard. Remove one screw holding this guard in position and lift out guard.
(3) Disconnect front universal joint. Remove lock wires and four cap screws holding the front propeller shaft universal joint bearing housings to yoke, pry propeller shaft back to telescope rear yoke on transfer unit shaft, and break joint.
(4) Remove propeller shaft. Lift propeller shaft up and pull off from transfer unit shaft. Remove shaft from vehicle through the driver’s door. Use care not to damage oil seal surface of sliding yoke.
5. Installation. (1) Install propeller shafts in vehicle. Lower
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propeller shaft into the vehicle through driver’s door opening. Slide yoke on rear end of shaft through seal and over splines of transfer unit output shaft.
(2) Connect front universal joint. Raise front end of shaft and telescope shaft on transfer unit output shaft until sufficient room is provided to connect front universal joint. Line up bearing housings with yoke on controlled differential pinion shaft. Install four cap screws, tighten to 85- to 95-foot-pounds torque, and install locking wires.
(3) Install propeller shaft guard. Install left propeller shaft guard and fasten in place with one screw.
(4) Install periscope stowage box. Place periscope and spare head stowage box in position on support brackets and fasten securely with four cap screws.
128. Final Drive Propeller Shafts
a. Removal. (1) Remove shield and guard. Remove four cap screws holding propeller shaft shield to mounting brackets on controlled differential and final drive housing and remove shield.
(2) Disconnect outer universal joint. Remove locking wire and four screws (fig. 114), holding universal joint bearing housing to yoke on final drive input shaft. Slide propeller shaft toward differential as far as it will go and disconnect universal joint.
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"HIGH” AND "LOW” SHIFT
CONTROL LEVER SHAFT
SHIFT LINK _ CLEVIS PIN
RA PD 331854
Figure 115. Removing transfer unit shift lever.
engages the arm and lever assembly for the HIGH and LOW shifter shaft. This moves the high and low gear synchronizer clutch along the mainshaft to engage the gear selected by the driver.
b. Removal. (1) Remove periscope box. Remove four screws holding the box to the four supporting brackets and one screw holding box to bulkhead extension at right side. Push transfer unit shift lever to the REVERSE position and remove box assembly.
(2) Remove shift lever spring and guide. Lift up on spring guide to compress spring until guide clears hole in shifter lever cross shaft. Remove spring and guide (fig. 115).
(3) Remove shift lever shaft damp bolt. Remove nut and washer from shift lever clamp bolt and remove bolt.
(4) Remove shift lever shaft. Slide shift lever cross shaft out of support bracket toward driver’s seat.
Caution: Arm and lever assemblies and spacer washers will drop down when shaft is removed.
Note position of parts before removing shaft so they will be reinstalled in the proper sequence.
(5) Remove shift lever assembly. Tilt top of lever toward right side of vehicle so that bottom part of lever comes out of side of support bracket. Raise driver’s seat to allow room for removing lever.
c. Installation. (1) Position shift lever in support bracket. Slide top of shift lever through opening in left side of support bracket so that top of lever comes out through opening on quadrant.
214
"HIGH” AND "LOW” GEAR SHIFTER SHAFT
REVERSE GEAR SHIFTER SHAFT
EXIENSION CLAMP SCREWS SHIFT CONTROL / r~
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SHIFTER SHAFT EXTENSION
Figure 116. Transfer unit shift linkage.
V~INPUT CLUTCH
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Figure 111. Removing engine input clutch lever.
215
(2) Install shift lever cross shaft. Slide shift lever cross shaft through opening in support bracket.
Note. Do not slide shaft all the way in.
Raise REVERSE lever and arm assembly, and slide on end of shift lever cross shaft. Next, place one of the spacer washers on shaft and slide shaft through hole in shift lever. Install another spacer washer over shift lever shaft. Raise HIGH and LOW lever and arm assembly up into position. Slide shaft through this arm also. Install the last spacer washer over the shift lever shaft and slide shaft into other end of support bracket. Line up notch in shaft with hole in bracket and install clamp bolt, nut, and washer.
(3) Install shift lever spring and guide. Slide spring and guide onto pin on shift lever. Compress spring on guide so that guide will enter cut-out on shift lever cross shaft.
(4) Install periscope box. Place transfer unit shift lever in reverse position to allow room to install box. Slide box into position on the four supporting brackets, and install four screws and washers at supports and one screw at bulkhead extension.
d. Linkage Adjustment. (1) Check adjustment. Move shift control lever from HIGH to LOW and from LOW to NEUTRAL to locate by feel the middle of the neutral detent position. Shift lever should now be in line with gate in quadrant opposite NEUTRAL. If it is not, readjust as explained below. When HIGH-LOW shift rod is properly adjusted, move shift lever through gate toward driver. Slot in bottom of shift lever should line up with lug on reverse lever and arm assembly. If it does not, readjust reverse shift rod as explained below.
(2) Remove periscope box. Remove five screws holding the box to the four supporting brackets and bulkhead. Push transfer unit shift lever to REVERSE position and remove box assembly.
(3) Adjust high-low shift rod. Loosen lock nut on shift link and turn threaded adjusters (fig. 116) in or out until the shift lever is in the center of the gate in the quadrant when the HIGH-LOW shift rod in the NEUTRAL detent position. Tighten lock nut on shift link.
(4) Adjust reverse shift rod. After HIGH-LOW shift rod has been adjusted, adjust REVERSE shift rod in same manner so that the slot in the bottom of the shift lever will be in line with the lug on reverse lever and arm assembly. Shift lever should engage HIGH and LOW lever, and REVERSE lever without interference.
(5) Install periscope box. Position transfer unit shift lever in REVERSE. Slide periscope box into position on four supporting brackets and install attaching screws.
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131. Engine Input Clutch Lever
a. Description. Two input clutch levers, one for each engine, are mounted on vertical shafts on each side of the transfer unit. When a lever is in the rear position, the sliding clutch on the input gear is engaged with the input shaft. When the lever is moved forward, the sliding clutch is disconnected.
6. Removal. Open sliding door over top of transfer unit and raise screen. Remove input lever clamp screw and lift off lever (fig. 117).
c. Installation. Place input clutch lever over input clutch shaft and install clamp screw. Close screen and sliding door over transfer unit.
132. Transfer Unit Replacement
a. Authority. Replacement of this major assembly with a new or rebuilt unit is normally a field maintenance operation, but may be performed in an emergency by organizational maintenance units, provided authority for performing this replacement is obtained from the appropriate commander. Tools needed for the operation which are not carried in organizational maintenance units may be obtained from a higher maintenance unit.
6. Removal. (1) Remove engines. Refer to paragraph 67.
(2) Remove radiators. Refer to paragraph 118a.
(3) Remove lower radiator seal. Remove four screws holding lower radiator seal to engine bulkhead. Lift out seal.
(4) Remove radiator center support. Working from driving compartment, remove two screws holding center radiator support to front of engine bulkhead. Remove four screws holding center radiator support to rear radiator support. Lift out support.
(5) Remove lower fire extinguisher pipes. Remove four clamps holding pipes to hull floor. Disconnect lower center fire extinguisher pipes at hull side wall connections, and remove screws holding center bracket to hull floor. Remove pipes as an assembly.
(6) Remove throttle relay rods. Disconnect and remove inter-mediate-to-rear throttle relay rod and rear relay as an assembly.
(7) Remove engine front support cushions. Remove eight screws holding engine front rubber cushions to engine front support brackets and remove cushions.
(8) Disconnect shifter shaft extensions. Remove shifter shaft extension clamp screw that locks extension to shifter shaft (fig. 116). Drive a small wedge or a chisel in slot in extension until extension is free on shaft. Move shifter lever towards HIGH to slide extension off high-low shifter shaft and towards REVERSE to slide extension off reverse shifter shaft.
(9) Loosen bulkhead extension shifter shaft seals. Remove four screws which attach shifter shaft seal to bulkhead extension and pull
217
seal away from bulkhead enough to clear transfer unit housing at shifter shaft (fig. 113). It is not necessary to disconnect other linkage and remove seal completely.
(10) Remove propeller shaft rear yoke seal retainers at bulkhead extension. To provide additional clearance, remove four screws holding seal retainer halves to bulkhead extension and remove retainers. Seal is split and may be removed from yoke if condition indicates necessity.
(11) Remove transfer unit. Attach a rope sling around transfer unit as shown in figure 118. Remove the three transfer unit mounting screws. Attach chain hoist to rope sling, and take up weight of transfer unit. Raise transfer unit and slide toward rear of vehicle until propeller shaft universal joint yoke slides off splines of transfer unit output shaft. Raise transfer unit and remove from vehicle.
c. Installation. (1) Place transfer unit in vehicle. Attach a rope sling around transfer unit, being sure that it is tied as short as possible (fig. 118). Then connect chain hoist to unit. Lower unit into vehicle. Before lowering unit all the way into position, slide propeller shaft rear yoke onto transfer unit output shaft, and also place the two shifter shaft extensions over the two shifter shafts. Slide transfer unit forward until it rests on the rubber cushion supports. Remove hoist and rope sling.
(2) Install mounting screws. Install two front and one rear transfer unit mounting screws and tighten securely.
(3) Install bulkhead extension shifter shaft seals. Position seal over shifter shaft and install four screws attaching seal to bulkhead extension (fig. 116).
(4) Install propeller shaft rear yoke seal and retainers. Inspect conditions of felt seal at propeller shaft yoke and replace with new seal if found to be badly worn or damaged. Seal is split at an angle to allow removal or replacement without removing propeller shaft yoke. Install seal around propeller shaft yoke and position metal retainers around seal. Install four screws attaching retainers to bulkhead extension.
(5) Connect shifter shaft extensions. If extensions were not positioned on shifter shafts while lowering transfer unit to final position, move transfer unit shift lever and at the same time slide shifter shaft extensions onto shifter shafts. Install shifter shaft extention clamp screw at both extensions and tighten clamp screw securely.
(6) Adjust transfer unit shift linkage. Refer to paragraph 130(4).
(6) Refill controlled differential. Refer to paragraph 36.
137. Oil Cooler
a. Removal. (1) Elevate the tube. Elevate the howitzer tube to maximum elevation.
(2) Remove Air Inlet Assembly. Remove 11 screws from each end of air inlet assembly and lift out assembly (fig. 104).
(3) Disconnect cooler hoses. Disconnect both cooler hoses at bulkhead connection by holding hose stationary with one wrench and turning coupling with another wrench (fig. 121). Plug ends of hoses immediately to prevent oil from running out over radiators.
Note. Radiators will clog with dust quickly if oil drips on them.
(4) Remove cooler. While a helper supports cooler from top of vehicle, remove four cap screws on fighting compartment side of bulkhead that hold mounting brackets to bulkhead. Lift out cooler.
(5) Remove cooler hoses. After cooler has been removed from vehicle, turn on one end to drain oil from unit, and then remove both cooler hoses from ends of cooler by unscrewing hose connections.
b. Installation. (1) Install cooler hoses. Coat threaded end of cooler hose fittings with gasket paste, and then install in fitting on end of cooler.
(2) Install cooler. Lower cooler assembly into position over front of radiators until holes in cooler brackets line up with holes in bulkhead. While helper holds cooler in this position, install four oil cooler mounting screws from inside vehicle.
(3) Connect oil cooler hoses. Connect both oil cooler hoses to connections on bulkhead.
Note. Use two wrenches to connect coupling to keep hoses from twisting (fig. 121).
(4) Install air inlet assembly. Lower air inlet assembly into position in opening and install 11 attaching screws and washers. Depress howitzer tube.
224
138. Controlled Differential Replacement
a. Authority. Replacement of this major assembly with a new or rebuilt unit is normally a field maintenance operation, but may be performed in an emergency by organizational maintenance unit, provided authority for performing this replacement is obtained from the appropriate commander. Tools needed for the operation which are not carried in organizational maintenance unit may be obtained from a higher maintenance unit.
6. Removal. (1) Remove differential opening cover.
(2) Remove periscope and spare head stowage box.
(3) Disconnect steering brake levers. Release brakes and push levers forward to the fully released position. Remove cotter pins and clevis pins holding right and left steering and braking control rods to lower end of relay on controlled differential housing (fig. 122).
(4) Remove pull-back springs. Grasp end of pull-back spring with heavy pliers and pull back until spring is clear of relay (fig. 122). Release spring gradually until it is free. Leave front end of spring connected to hull front plate.
(5) Remove left propeller shaft guard. Remove screw holding left propeller shaft guard to support brackets and remove guard.
(6) Remove right propeller shaft guard. Remove four screws holding right propeller shaft guard to support brackets and remove guard.
DIFFERENTIAL OIL COOLER U COOLER HOSE Z BULKHEAD
- • TW. •
wA V < nV
COOLER MOUNTING BRACKET RA PD 331325
Figure 121. Disconnecting oil cooler hose.
225
(7) Remove stop light switches. Remove cotter pin and slide stop light switch rod off pin on relay arm (fig. 122). Remove two screws holding stop light switches to front differential mounting brackets. Lay switches to one side so they will not be damaged.
(8) Drain oil. Drain oil by removing small plate under hull floor at front of vehicle and remove differential drain plug. After oil has drained, reinstall plug.
(9) Disconnect oil cooler lines. Disconnect oil cooler lines at right rear corner of differential by unscrewing coupling on line from fitting on housing (fig. 120).
Caution: Place rags or container under lines to catch any oil that may drain out of cooler lines.
(10) Remove final drive propeller shaft shields. Remove four screws holding both halves of final drive propeller shaft shields to mounting brackets. Then remove the shields. Remove two screws boldine- shield brackets to sides of controlled differential housing and remove brackets.
DIFFERENTIAL MOUNTING BOLTS
| RETRACTING SPRING I SPEEDOMETER CABLE
a,*
\Jjy 1
y I M J*
STOP LIGHT SWITCH STEERING STEERING BRAKE L H. PROP CONTROL ROD CONTROL LINK INTERMEDIATE RELAY SHAFT GUARD
Figure 122. Steering brake linkage and differential mounting.
226
(11) Disconnect inner ends of final dr-ire propeller shafts. Remove lock wires from inner universal joint bearing housing screws. Remove four screws holding universal joint bearing housings to controlled differential yoke. Slide yoke into controlled differential housing and disconnect joint.
(12) Disconnect differential to transfer unit propeller shaft. Remove lock wires from front universal joint bearing caps. Remove four screws holding bearing caps to differential yoke. Slide propeller shaft back, telescoping rear yoke on transfer unit output shaft and disconnect joint.
(13) Disconnect speedometer cable. Disconnect speedometer cable (fig. 122) on differential by unscrewing knurled nut on cable and pulling core out of case. Remove cable from slip on case and lay cable to one side.
(14) Remove differential mounting bolts. Remove two front and one rear differential mounting bolts and nuts and remove bolts.
(15) Remove differential. Attach chain hoist to lifting bracket on differential cover. Take up weight of differential on hoist until it clears mounting brackets on hull floor. Raise differential very slowly, and see that it does not strike instrument panel (fig. 123). Remove differential and lower to ground. Remove chain hoist.
c. Installation. (1) Place differential in vehicle. Attach a chain hoist to lifting bracket on differential cover. Raise differential over opening in hull front deck. Lower assembly, being careful that it does not strike instrument panel. Lower assembly on support brackets. Remove chain hoist from cover.
(2) Install differential mounting bolts. Install two front and one rear differential mounting bolts through boss on differential case and brackets on hull (fig. 122). Install nuts and washers and tighten nuts to 200 foot-pounds, using a torque wrench.
(3) Install speedometer cable. Place speedometer cable in clip on differential case. Slide speedometer core into drive shaft sleeve and install knurled nut holding cable to sleeve.
(4) Connect transfer unit to controlled differential propeller shaft. Slide propeller shaft forward, line up universal joint and install four screws holding bearing journals to differential yoke. Using a torque wrench, tighten screws to 80 foot-pounds. Lock screws in pairs with locking .wire.
(5) Connect inner ends of final drive propeller shafts. Raise propeller shaft and position final drive bearing caps on differential drive yokes. Install screws holding bearing caps to yoke. Using a torque wrench, tighten screws to 80 foot-pounds. Lock screws in pairs with locking wire.
(6) Install final drive propeller shaft shields. Install brackets holding propeller shaft shields to side of differential housing. Position
227
upper and lower section of propeller shaft shield over mounting bracket and install eight screws and washers.
(7) Connect oil cooler lines. Insert oil cooler lines into fittings in controlled differential case and connect coupling on lines to fittings in case (fig. 120).
(8) Refill controlled differential. Fill controlled differential with approximately 20 quarts of engine oil. Recheck level on gage.
(9) Install stop light switches. Place stop light switches in position on front differential mounting brackets and install four screws and washers. Slide rod over pin on steering and braking relay and install flat washer and cotter pin (fig. 122).
(10) Install right propeller shaft guard. Place right propeller shaft guard against support brackets and install four screws and washers.
(11) Install left propeller shaft guard. Place left propeller guard against support brackets and periscope stowage box, and install screw and washer.
(12) Install pull-back springs. Make sure front end of spring is hooked to bracket on hull front plate. Pull back on end of spring
fa
LIFTING EYE
CONTROLLED ( *
DIFFERENTIAL^^Oj^^^Z^,
f xrl i FINAL DRIVE YOKE r
gjfifffrential OPENING .... ■
Figure 123. Removing controlled differential.
228
with large pliers, and hook end of spring over cut-out in steering and braking lever relay (fig. 122).
(13) Connect brakes. Line up hole in connecting rod yoke with hole in lower steering brake relay. Install clevis pin and cotter pin.
(14) Adjust linkage. Adjust length of connecting rod to permit free assembly of pin at steering lever by loosening lock nut and rotating clevis. Turn clevis one-half turn tighter to assure taking out all slack, and tighten lock nut. Connect rod to lever and install clevis pin and cotter pin. Adjust other lever in same manner.
(15) Adjust steering brakes. Refer to paragraph 1346.
(16) Install spare periscope box. Refer to paragraph 130c.
(17) Install differential opening cover. Refer to paragraph 1356 (6).
Section XXXI. FINAL DRIVE
139. Description and Data
a. Description. The final drive units are mounted in separate housings bolted to the front of the hull on each side (fig. 125). The final drives are designed so that they are interchangeable right to left and can be installed on either side of the vehicle. Power is transmitted to the final drives from the controlled differential through short propeller shafts having large universal joints at each end. The herringbone gear set provides a reduction ratio of 2.94 to 1. Power output is through the sprocket shaft, which carries the track driving hub and sprockets.
b. Data.
Bracket----------------------------------- Cast steel.
Cover------------------------------------- Cast steel.
Gear ratio________________________________ 2.94 to 1.
Sprocket, teeth___________________________ 13.
Type of gear------------------------------Spur (herringbone).
140. Sprockets and Hubs
a. Removal. (1) Break track. Break track below and to the rear of final drive, and lift track over and to the rear of hub and sprockets (par. 144).
(2) Remove sprocket and hub assembly. Remove 10 nuts attaching hub to shaft and remove hub and sprocket as an assembly.
(3) Remove sprockets. Remove 13 screws attaching each sprocket to hub and remove sprockets.
b. Installation. (1) Install sprockets. Install sprockets on hub and tighten 13 screws on each sprocket securely.
(2) Install hub assembly on shaft. Position hub and sprocket assembly on shaft, line up holes, and install and tighten the 10 mounting nuts securely.
229
(3) Install track. Refer to paragraph 144&.
(4) Adjust track. Refer to paragraph 143&.
c. Reversing Sprockets. When the teeth on the sprockets become worn from usage, the sprockets can be reversed on the hub or the complete hub and sprocket assembly can be changed from right to left, and vice versa. This will present a new tooth surface to the track and provide longer life.
141. Final Drive Replacement
a. Authority. Replacement of this major assembly with a new or rebuilt unit is normally a field maintenance operation, but may be performed in an emergency by organizational maintenance units, provided authority for performing this replacement is obtained from the appropriate commander. Tools needed for the operation which are not carried in organizational maintenance units may be obtained from a higher maintenance unit.
b. Removal. (1) Drain lubricant. Remove cover plate that protects final drive drain plug from bottom of hull beneath final drive. Remove drain plug.
(2) Remove guards. Remove four screws holding halves of final drive propeller shaft guard to controlled differential and to final drive case, and remove guard.
OUTER SPROCKET—| INN
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fMfc I //Z" i
SPROCKET HUB ^ ^HUB MOUNTING NUTS (10)
Figure 124. Removing trade sprocket.
230
FINAL DRIVE MOUNTING SCREWS—. 15/16zz SOCKET
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; TRACK GUIDE 7 --SHOCK ABSORBER x~TRACK SHOE
: DRIVE SPROCKET TRACK WHEEL rA PD 331823
Figure 127. Track suspension system.
(2) There are 10 dual track wheels, 5 on each side, which are carried on individual arms attached to independent torsion bars and mounted so as to be easily removable (fig. 127). The 10 arms are each mounted on 2 roller bearings carried in housings bolted to the sides of the hull just above the floor level. The arms are splined to the torsion bars, which extend through protective tunnels on the hull floor. The torsion bars for opposite wheels are staggered to permit carrying the wheels at the same level. Double-acting, airplane-type, hydraulic shock absorbers are provided for the two front and two rear suspension arms on each side, and are mounted directly on the hull side walls (fig. 127).
(3) An adjustable compensating wheel for each track is mounted at the rear of the hull, and is connected to the rear-track wheel arm by a link (fig. 136). The link is so arranged that any decrease in track tension caused by lifting of the rear track wheels will be offset by movement of the compensating wheel toward the rear, and any increase in track tension caused by dropping of the rear track wheels will be offset by movement of the compensating wheel toward the front.
(4) Four dual, rubber-tired track support rollers are mounted on each of the upper hull sides (fig. 127) to support the track as it returns to the drive sprocket.
b. Data. (1) Track shoes.
Number per track______________________
Width_________________________________
Type----------------------------------
(2) Track.
Pitch_________________________________
Ground contact:
Zero penetration__________________
1-inch penetration________________
(3) Suspension arms.
Number (each side)____________________
Type----------------------------------
Type of springing_____________________
Number of bearings____________________
(4) Track wheels.
Number (each side)____________________
Type----------------------------------
Number bearings (each wheel)__________
(5) Torsionbars.
Number (each side)____________________
Type----------------------------------
80.
16 inches.
Steel, with center guide and rubber bushings.
514 inches.
122 inches.
126 inches.
5.
Solid steel..
Torsion bar.
2 (straight-roller).
5.
Dual, demountable, rubber-tired.
2 (taper, roller).
5.
Solid steel.
234
Installation identification:
Position Part No.
Left, Nos. 1 and 2_______________________D60591B
Right, Nos. 1 and 2______________________D60591A
Left, Nos. 3, 4, and 5___________________ 7053475
Right, Nos. 3, 4, and 5__________________ 7053474
(6) Track support rollers.
Number (each side)______________4.
Type----------------------------Dual, demountable, rubber-tired.
Bearings________________________2 (taper, roller).
(7) Shock absorbers.
Number (each side)______________4.
Type-----------------------------Hydraulic, airplane-type.
(8) Suspension arm cushion stops.
Number (each side)______________ 5.
Volute spring.
Type
143. Track Adjustment
a. General.
Caution: It is important that the tracks be properly adjusted to prevent unnecessary wear and breakage.
b. Procedure. (1) To check the track adjustment, move vehicle to level ground to assure normal track tension. Place a 4-foot pry bar and improvised hook between the track and suspension arm housing at a point midway between the second and third track support rollers. Pry down with lever so that about 200-pounds pressure is exerted at track and, at the same time, lay a straightedge along the top of the track between the second and third rollers and measure the sag
3/4 TO1 INCH—. STRAIGHTEDGE
7(A /ER A-1
a®
THIRD TRACK R^fl^SECOND TRA<3FROLLER 7 W RA PD^1824
Figure 128. Testing track tension.
235
LOCK PLATE
C ADJUSTING
NUT
Figure 129. Adjusting track tension.
BOLT
PD 331825
at this point (fig. 128). This sag should be from % to 1 inch with 200-pounds load applied. Track tension must be adjusted to above figure when sag becomes 1% inches or more.
(2) If the track adjustment is incorrect, loosen clamp bolt at rear of compensating wheel arm (fig. 129) and slide lock plate up from adjusting eye bolt sleeve nut. Tighten or loosen adjusting sleeve nut to obtain correct track tension. Tighten clamp bolt after positioning lock plate on flat of adjusting sleeve nut.
144. Track Replacement
a. Removal. Install track fixtures (41-F-2997-86) on track midway between compensating wheel and rear track wheel (fig. 131), and take up track tension. Remove track shoe pin wedge screw, lock washer, and flat washer (fig. 130). Using a brass drift, drive wedge out of block. Tighten track fixtures to relieve track tension and drive out connecting pin, using knock-out pin (41-P-560-300) (fig. 131). Remove fixtures, start engines, and put transfer unit and transmission shift levers in drive position and run engines just fast enough to turn track drive sprocket slowly. Then run upper half of track forward off support rollers and drive sprockets. Tow vehicle off track. If new track is to be installed, place new track in front of old track and tow vehicle onto new track.
b. Installation. Lay track out on ground and tow vehicle on track so that rear end of track projects approximately 10 inches beyond rear track wheel. Pull front end of track up over drive sprocket and start engines, put transfer unit in reverse and transmission in
236
TRACK SHOE—r WEDGE SCREW / LOCK WASHER
/ ZF y /A /A FLAT WASHER
SHOE GUIDE--f-->7 .
hr fa f f r ♦
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I '"F ^******^
TRACK PIN WEDGE-J I T *
TRACK PIN-* W
TRACK PIN BUSHING-
Figure 130. Track block—disassembled.
drive, and guide track back over support rollers and compensating wheel as rotation of drive sprocket moves upper half of track back. Mount track connecting fixtures (41-F-2997-86). Bring track ends together by tightening fixture and drive in track shoe pin (fig. 132). Be sure that slots in pin enter guides in pin bushing (fig. 130) and that pin enters bushings without damaging bushing ends. Install track shoe pin wedge in hole in shoe with beveled end in, tap wedge lightly to its seat, and install flat washer, lock washer, and wedge screw. Tighten screw to 110 foot-pounds. After run in, retighten screw to 80 to 90 foot-pounds. Adjust track tension (par. 143).
Caution: Be sure to install track so that grouser on block contacts ground first as shown in figure 1.
145. Compensating Wheel, Bearings, and Seals
a. Removal. Break track at rear of vehicle (par. 144«) and pull top half of track forward to clear compensating wheel. Remove 10 nuts and locks holding dual compensating wheel on studs and remove wheels. Remove four hub cap mounting screws, and remove hub cap and gasket. Take out cotter pin, nut, and washer holding hub on spindle (fig. 136). Pull out on hub enough to loosen outer bearing. Remove outer bearing. Lift off hub and inner bearing. Pry grease seal off spindle bearing spacer with screw driver.
b. Installation. Place new oil seal on spindle with feather edge toward arm and, using oil seal replacer (41-R-2383-950), tap over bearing spacer until seal contacts spacer (fig. 140). Place wheel hub on bench with wheel side down and pry grease retainer out of hub.
752022 O—47-----16
237
REAR TRACK WHEEL-, r COMPENSATING WHEEL
* f J ■ A3E5» k *■• i- f . ■^y .4 ->■
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BLOCK PIN -A ‘ TRACK CONNECTING FIXTURES—7
DRIFTPIN (41-F-2997-86) RA PD 331340
(41-P-560-300)
Figure 131. Removing track pin.
TRACK CONNECTING PIN-, p TRACK WHEEL z—COMPENSATING WHEEL
! If ' WVfl
H...... v B f
PIN WEDGE SLOT-/ TRACK FIXTURE (41-F-2997-86)-V RA PD 331373
Figure 132. Connecting track.
238
WHEEL ' DIRT SHEDDER —7
(SCREW LOCK W /
IWASHER NUTy r—INNER CONE /
v74| i \
wilB' j ' ^°ilsea*\\\
\ WB I W / BEARING SPACER A \ / NUT-^ \ \ f / SEAL SPACER—A
Z-HUB CAP \ \ w\, / 1 W gy /
KEYED WASHErA \ ASSEMB'Y
OUTER CONE-A -WHEEL, ASSEMBLY RA PD 331375
Figure 133.
Wheel hubs, bearings, and seals—disassembled.
Place new grease retainer in replacer (41-R-2390-450) (fig. 134) and position replacer on hub. Drive retainer carefully into position (fig. 135) to prevent cocking in hub and remove tool. Check retainer to see that it is square in the hub counterbore and that the flange of retainer is true. Grease inner roller bearing assembly thoroughly with lubricant and push on spindle shoulder until bearing contacts spacer. Push hub assembly on spindle, making sure inner bearing enters race in hub. Fill outer roller bearing with grease and install on spindle, holding wheel hub centered on spindle and pushing outer bearing into race. Install keyed washer on spindle and seat on bearing. Install nut on spindle.
c. Adjustment. Rotate hub and, at the same time, tighten nut to 200 foot-pounds torque. Back off nut until there is no torque, then retighten nut to 75 foot-pounds torque. Back off nut to first cotter pin hole with minimum travel of 15° and install cotter pin. If first hole is less than 15° travel, back off nut to next hold or 30° more. Position hub cap and install four mounting screws. Using pressure gun, force more grease into hub until it starts coming out of grease shield at rear. Wipe off all excess grease. Lift wheels and install on hub studs, the first wheel with concave side in, the second with concave side out. Install 10 nuts with locks and tighten evenly with 250 to 300 foot-pounds. Install and adjust track (pars. 1446 and 1436).
146. Compensating Arm and Lever
a. Removal. Remove compensating wheel and hub as previously outlined in paragraph 145a. Remove cotter pin, nut, and washer from compensating link bolt at rear end of link. Install slide hammer adapter (41-A-18-245) on link bolt head, being sure that stud is screwed all the way in bolt and hexagon shoulder of adapter seats on
239
bolt head. Attach slide hammer puller (41-P-2957-33) and pull bolt (fig. 137). Push link end down and out of compensating lever. If necessary, hook hoist on rear suspension wheel and raise wheel. This will move link end to rear of vehicle so that drift and hammer can be used to drive out bolt. Remove six attaching screws and remove compensating arm cover (fig. 136) ; then discard gasket. Remove lock ring holding arm and lever on compensating wheel spindle and lift support arm and lever off spindle as an assembly. Remove screws holding spindle to tapping plate on hull and remove spindle.
b. Installation. Coat flange of spindle with sealing compound and position spindle on hull tapping plate, and install eight mounting screws dipped in sealer. Tighten screws to 240 to 260 foot-pounds, using torque wrench. Install arm and lever assembly on spindle, seeing that shoulders on spindle enter bearing races and that grease seal slips over bearing spacer. Install snap ring on spindle end to hold assembly. Using new gasket, position compensating arm cover and install six attaching screws. Connect compensating link to lever (fig. 136) and drive in bolt, using a soft hammer; then install washer, nut, and cotter pin. Tighten washer and nut on connecting bolt to 180 foot-pounds minimum. Install compensating wheel and hub (par. 145Z>) and adjust (par. 145c).
c. Compensating Arm Bearing Replacement. (1) Remove compensating arm and lever. Refer to a above.
GREASE RETAINER REPLACER (41 -R-2390-450) “x. GREASE RETAINER
Lg-V
/' >'' ' AZ'
I \ .jA /
k , \ - " r /
I'■ \ jdh
% \ .......
TRACK WHEEL
9 \ 9 HUB
INNER BEARING CUP-*
Figure 134. Wheel hub grease seal retainer in tool.
240
(2) Remove bearings. Remove lever clamping bolt, lock plate, and washer (fig. 130). Remove adjusting sleeve nut and thrust washer. Remove lever with adjusting eye bolt from support arm body. Tap inner roller bearing and grease retainer out of wheel support arm. Tap out the outer ball bearing.
(3) Install bearings. Grease bearings thoroughly with specified lubricant. Reinstall bearings in support by tapping in until they seat on shoulders in arm, using a block of wood or a brass drift. Place new grease seal in inner side of arm with featheredge toward vehicle and tap in until it seats on shoulder of arm. Install adjusting eye bolt in lever, and place adjusting sleeve nut (thoroughly greased with lubricant) and thrust washer on eye bolt. Install lever with eye bolt and nut on arm. Install lock plate and lock washer on clamp bolt and turn bolt into lever.
(4) Install compensating arm andlever. Refer to & above.
147. Compensating Link
a. Removal. Remove compensating wheel and hub (par. 145 rh*
&**• . H V-jLij \ "^"*- *
W Ujr/ \ j|
SLIDE HAMMER PULLER (41-P-2957-33; COMPENSATING LINK
Figure 137. Removing compensating link pin.
cushion stop bracket, making sure that top of hook is between spring mounting screw and bracket mounting screws (fig. 138). Drive vehicle slowly either forward or backward until track wheel next to the one to be removed rests on top of the wheel lifting block. Set brakes and stop engines. Remove 10 nuts holding wheels to hub and •lift off wheel. If wheel lifter (41-L-1400) is not available, set brakes and place a block of wood (2 by 4 inches or 2 by 6 inches) against inside edge of track. Position hydraulic jack with base of jack on track and block of wood under suspension arm to be lifted (fig. 139). Lift suspension arm until wheel clears track guides. Remove 10 nuts holding dual wheels to hub and lift off wheels.
Caution: Exercise care in lifting arm to prevent arm end from slipping off jack as a lift of approximately 9,000 pounds is required to raise arm sufficiently to remove wheels.
(2) Remove wheel hub. Remove four hub cap mounting screws (fig. 133), remove cap, and discard gasket. Remove cotter pin, nut, and keyed washer that hold hub assembly on spindle. Pull hub out enough to move outer roller bearing out of cup in hub, and remove bearing. Pull hub assembly off spindle, and remove inner bearing.
(3) Remove oil seal. Pry oil seal off bearing spacer on spindle (fig. 133) and discard.
Note. Exercise care in prying off seal, or dirt shedder in back of seal will be damaged necessitating installation of new shedder.
Place hub assembly on bench with wheel side down and pry out grease retainer (fig. 134).
243
CUSHION STOP BRACKET
TRACK WHEEL (RAISED)
LIFTING BLOCK
■ ' -lb-*--— •
SUSPENSION ARM HOOK
Lifting Track Wheel
CUSHION STOP MOUNTING SCREW
WHEEL MOUNTING NUTS
TRACK WHEEL (READY FOR REMOVAL)
SUSPENSION ARM HOOK
LIFTING BLOCK
Track Wheel on Hook
CUSHION STOP MOUNTING .
SC R E W - -V
SUSPENSION •/ * -fe' SUSPENSION
ARM-^-i|ipMS—■ arm hook
TRACK .
WHEEL LIFTING BLOCK
Track Wheel Removed
Figure 138. Lifting track wheel, using lifter (41-L-lJfOQ).
244
(4) Remove bearing races. Drive bearing races out of hub carefully, using a brass drift and a hammer.
b. Installation. (1) Install bearing races. Drive bearing races into wheel hub, using a brass drift or block of wood and being careful to prevent cocking of race in hub.
(2) Install oil seal. Place new oil seal over spindle with featheredge of seal toward arm and, using oil seal replacer (41-R-2383-950), drive seal into position on bearing spacer (fig. 140). Place new grease retainer in replacer (41-R-2390-450) (fig. 134), and position replacer on hub. Drive retainer into position (fig. 135) carefully to prevent cocking in hub, and remove tool. Check retainer to see that it is square in hub counterbore and that the flange in retainer is true.
(3) Install wheel hub. Pack inner roller bearing thoroughly with specified grease and push on spindle and over shoulder. Lift hub assembly onto spindle and over inner bearing. Pack outer bearing with grease and push on spindle and into race in hub, centering hub on spindle. Install keyed washer and bearing retaining nut. Adjust wheel bearing (par. 145c). Place hub cap on hub using new gasket, and install four mounting screws. Connect lubricating gun to fitting on hub and force grease into hub until excess grease comes out in back of hub. Wipe off all excess grease.
(4) Install wheel. Position dual track wheels on hub. Install 10 mounting nuts and tighten to 250 to 300 foot-pounds. If wheel lift
HYDRAULIC JACK SUSPENSION ARM
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TRAC^^HEe7-J^^^L-WOOD BLOCKS RA PD 331388
Figure 139. Lifting track wheel with hydraulic jack.
245
SUSPENSION
ARM
OIL SEAL REPLACER (41-R-2383-950)
Figure 140. Installing wheel hub seal.
ADAPTER (41-A-l 8-245)
SLIDE HAMMER PULLER (41-P-2957-33)
PENSION ARM TORSION BAR
Figure Djl. Removing torsion bar.
246
-OIL SEAL
(FEATHEREDGE IN)
was used for removing wheels, drive vehicle forward or backward slowly until track wheel lifting block is under wheel supported by suspension arm hook. Remove hook from suspension arm and cushion stop bracket. Drive vehicle in reverse slowly until lifting block is between drive sprocket and No. 1 wheel. Remove lifting block. Adjust the track (par. 1436). If wheel lift was not available and wheels were removed by using a hydraulic jack, position wheels on hub, install mounting nuts, and tighten to 250 to 300 foot-pounds. Lower track wheels to track and remove hydraulic jack and blocking.
149. Torsion Bars
a. Removal. (1) Disconnect shock absorber. Disconnect shock absorber at lower end (par. 152a).
(2) Remove track wheel. Place hydraulic jack under vehicle so that base of jack rests on track and block of wood and top of jack is under suspension arm. Raise arm high enough to remove the wheel. After wheels are removed, lower jack until all tension is removed from torsion bar.
(3) Remove torsion bar. Remove screw that holds torsion bar to bar retaining nut. Remove bar retaining nut. Screw adapter (41-A-l8-245) for slide hammer into torsion bar, being sure that stud is screwed all the way in bolt and hexagon shoulder of adapter seats on bolt head. Attach slide hammer puller (41-Rr-2957-33) to adapter, and pull shaft out of suspension arm (fig. 141).
6. Installation. (1) Identifying torsion bars. The suspension arm torsion bars have designating arrows stamped on the arm end. The arrows indicate the rotation of the bars when the wheel and arm are raised, or in other words, the direction of bar “spring.” The two front wheel bars on the right-hand side of the vehicle have designating arrows in clockwise rotation. The two front wheel bars on the lefthand side of the vehicle have arrows pointing in the counterclockwise rotation. The three rear suspension arm torsion bar on the right-hand side of vehicle have an arrow indicating counterclockwise, and the three rear arm torsion bars on the left-hand side of the vehicle have clockwise arrows. Be sure to install torsion bars in the correct locations. The two front bars on each side are smaller diameter bars and must be reinstalled in this position.
(2) Install torsion bars. The suspension arm torsion bars have designating arrows and part numbers stamped on arm end. The arrows indicate the rotation of the bars when the wheel and arm are raised. Slide the correct torsion bar into the tunnel until the inner end of the bar contacts the anchor. See paragraph 142 for torsion bar identification and position. Examine the outer end of the torsion bar and rotate it until the small slot that is cut in the chamfer is straight up (vertical). This will also insure a vertical blind spline at the
247
anchor end of the bar; a requirement for proper entry of the bar into its anchor. Gently tap the bar into the anchor with a soft-faced hammer. If the bar will not enter readily, loosen the cap screws holding the anchor supporting plate a little more and make certain that the four cap screws are loosened approximately the same amount. The two cap screws holding the anchor to the supporting plate do not have to be loosened. After the torsion bar has entered the anchor, raise the suspension arm until the small slot cut in the outer edge of the arm lines up with the blind spline in the outer end of the torsion bar. The torsion bar can then be tapped all the way into place. Install the torsion bar retaining nut and tighten to 75 foot-pounds. Install the cap screw in the retaining nut and tighten it to 65 footpounds. Tighten the torsion bar anchor plate screws to 35 footpounds.
(3) Install track wheel. Position hydraulic jack and block of wood under suspension arm on track edge, and raise arm until wheel can be installed. Position dual track wheel on hub studs and install ten wheel mounting nuts. Tighten nuts to 250 to 300 foot-pounds. Lower wheel to track and remove jack and blocking.
(4) Connect shock absorber. Connect shock absorber lower end to suspension arm (par. 1525).
150. Suspension Arm
a. Removal. Remove track wheel and torsion bar (par. 149a). Remove seven screws that hold suspension arm assembly to hull side and lift or hoist arm out of hull opening.
5. Installation. Coat suspension arm mounting plate flange on hull with joint and thread compound (cement, type II). Lift or hoist arm assembly into position on hull side and line up mounting ..crew holes with a drift punch. Dip seven arm-mounting screws in joint and thread compound, install in arm flange, and tighten to 240 to 260 foot-pounds. Install torsion bar and track wheel (par. 1495).
151. Track Support Rollers, Bearings, and Seals
a. Roller Removal. Place block of wood on track wheel nearest roller to be removed. Set jack on wood block and raise track until it clears roller (fig. 142). Remove five screws that hold roller mounting bracket to hull side wall, and remove roller.
5. Track Support Roller Installation. Coat flange of roller mounting bracket with joint and thread compound (cement, type II). Lift support roller assembly up until track guides enter space between rollers, and position mounting bracket on hull side wall. Line up mounting screw holes in bracket flange and hull side wall. Dip mounting screws in joint and thread compound and install, drawing up evenly.
248
ROLLER MOUNTING
TRACK
BRACKET—, r TRACK SUPPORT ROLLERr—WOOD BLOCK
,XJ _______________
8 -’. y'/xx AIS / 36B flflBflz
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X/ ' ^KL^~
V WBB 'll "Z******4^-
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ROLLER MOUNTING SCREWS HYDRAULIC JACK —> 2-WOOD BLOCK
Figure 142. Removing track support roller.
c. Bearing and Seal Replacement. (1) Removal. Remove track support roller as outlined in a above. Remove four screw.s that hold hub cap to wheel hub, remove cap, and discard gasket. Remove cotter pin and nut that hold bearings on roller spindle. Pull out on roller to move outer bearing and keyed washer out of roller hub. Remove outer bearing and washer. Lift roller and hub assembly off mounting bracket spindle. Remove inner bearing and grease retainer. Pry grease seal off bearing .spacer and discard.
Note. Remove grease seal carefully to prevent damage to dust shedder.
Remove bearing races from hub, using puller (41-P-2905-60).
(2) Installation. Install bearing races in roller hub by driving carefully into place with brass drift or block of wood until they seat in shoulders of hub. Place new grease seal on support spindle with featheredge toward mounting bracket and drive into position on bearing spacer, using seal replacer (41-R-2397-875) (fig. 144). Place new grease retainer in position on replaced (41-R-2396-375) with flanged edge against shoulder of tool, and drive into support roller (fig. 143), until it seats on hub shoulder. Pack inner bearing with specified grease and position on spindle. Install roller and hub assembly on
249
spindle and over grease seal and inner bearing, being careful to prevent buckling grease seal leather. Pack outer bearing with specified grease, and install on spindle and into race in hub. Install keyed washer and nut on spindle, and tighten adjusting nut to 150 foot-pounds torque. Back off nut until there is no torque. Retighten nut to 75-foot-pounds torque. Back off nut to first cotter pin hole with minimum travel of 15° and install cotter pin. If first hole is less than 15° travel, back off to next hole or 30° more. Using new gasket, position hub cap and install four screws. Install support roller assembly (b above).
152. Shock Absorbers
a. Removal. Working at upper end of shock absorber, remove cotter pin, nut, and washer that hold end of shock absorber to mounting bracket on hull side. Screw puller (41-P-2907-196) on bushing flange of shock absorber. Hold body of puller with large crescent wrench and turn down puller bolt, pulling shock absorber off pin (fig. 145). Working at lower end of shock absorber, remove cotter pin, nut, and washer that hold .shock absorber to mounting pin on suspension arm. Using puller (A7079316), remove lower end of shock absorber from mounting pin in same manner.
Note. Use of a longer %16NF 2-bolt in shock puller will permit pulling lower end of shock absorber completely off pin.
GREASE RETAINER
'Vf REPLACER
mH / <4I'R'2396'375>
TRACK SUPPORT^ . jjjl
ROLLER-----
Figure 1}3. Installing track roller hub grease retainer.
250
b. Installation. Lift shock absorber into position, and enter upper end bearing over mounting bracket pin. Drive bearing into position on mounting bracket carefully with a soft-faced hammer, install washer and nut, and tighten nut to 180 foot-pounds, using a torque wrench. Install cotter pin. Mount lower end of shock absorber on pin in suspension arm in the same manner.
153. Suspension Arm Cushion Stop
a. Removal. Remove bolt and spacing washer that hold volute spring in stop bracket and remove spring. Remove two bolts inside of stop bracket that hold assembly to hull side wall. Remove two mounting bolts that hold upper end of .stop bracket on hull side (fig. 136), and remove stop bracket.
b. Installation. Identify proper cushion stop bracket for right and left sides. When bracket is properly installed, the boss on the bottom of the bracket should point forward toward the wheel and install two upper screws and washer. Threads of screws should be well coated with sealing compound before installation. Working under stop bracket, install two lower mounting screws and washer. Tighten the four attaching screws to 80 to 85 foot-pounds torque.
Section XXXIII. HULL
154. Description and Data
a. Description. (1) The hull of the vehicle is a completely welded structure except for portions of the front, top, and floor, which are removable for service operations. These removable portions consist of a plate above the controlled differential at the front of the vehicle, two drivers’ doors over the drivers’ seats, a hinged air outlet door over the engine compartment, an air inlet grille over the radiator compartment, two stowage compartment doors at rear and removable covers (on each side) over each fuel tank and over each battery. Openings in the bottom of the hull include the two large inspection plates, one under each engine and transmission; and the small covers just beneath the drain plugs for the engines, hydramatic transmissions, transfer unit, controlled differential, and final drives.
(2) The hull floor carries the mounting brackets for the engine and transmission supports, the transfer unit supports and the differential supports. It also incorporates the tunnels in which the torsion bars for the track suspension wheels are carried. The hull is divided into three compartments: The driving compartment at the front, an engine compartment at the center, and the stowage compartment and gun mount platform at the rear. The two front compartments are separated by a bulkhead that extends from side-to-side and from the roof down to the bulkhead extensions, which in turn extend forward to
251
cover the transfer unit. Another bulkhead separates the engine and stowage compartments. The front of the hull slopes downward at the top and upward at the bottom to form a V. The sides of the hull slope inward at the bottom.
(3) Seats for the driver and assistant driver are mounted in the front of the hull. These seats have both an up-and-down and fore-and-aft adjustment (par. 11). Protective pads for driver and assistant driver are provided around the final drive propeller shafts, at the sides of the controlled differential and on the periscope head rests.
(4) The various stowage items carried in the hull are mounted in sheet metal containers which are bolted or latched to the hull floor and side walls. Ammunition stowage is provided in tubes under the gun mount platform, and in ammunition boxes carried on floor in rear compartment.
5. Data. For detailed data on the hull refer to paragraph 4^.
155. Sealing Hull Parts
a. General. Joint-sealing compound should be applied to detachable hull parts when they are assembled to the vehicle to prevent water, dust, or fine sand from seeping through the joints and entering the hull.
5. Parts To Be Sealed. (1) Differential opening cover.
(2) Final drive housings.
REPLACER
(41-R-2397-875)
OIL SEAL
DUST SHEDDER
SUPPORT ROLLER MOUNTING BRACKET
Figure 144- Installing track roller grease seal.
RAPI>-331376
252
(3) Drain valve flanges.
(4) All floor pans and drain plug covers.
(5) All bolts extending through the side of hull or through floor of hull.
156. Drivers’ Doors
a. Removal. Release door latch lever and allow spring pressure to raise door (fig. 10). With a helper to support door in this position, remove eight screws and washers holding hinge and lever assembly to hull roof. Remove door and hinge assembly by sliding lever out of hinge opening. Remove the door.
Note. Do not lose shims from under hinge flange.
b. Installation. Place shims over hinge flange and coat edge of flange with joint sealing compound. Lift door and hinge assembly into position above hinge opening. Slide latch lever and hinge through hinge opening and place in position on hull roof.
Note. Flat spot on hinge flange should be toward door opening.
With helper holding up end of door to keep flange on hinge even with hull roof, install eight screws and washers that hold hinge flange to hull roof.
c. Adjustment. Correct tension of the driver’s door hinge operating lever is important to insure doors being locked securely in open position. Check the adjustment by using a high-reading spring scale
SHOCK ABSORBER—-—_ • M ■
MOUNTING ..
BRACKET
PULLER ______________U T
(41-P2907-196) g) J B
Figure 145. Removing shock absorber.
752022 0—47-----17
253
hooked over the door hinge operating lever near the knob with the door open and the lever in locked position. A pull of 30 to 40 pound? should be required to release the lever. If the effort required to unlock the door is less than 30 or more than 40 pounds, readjust hold-open pin by raising pin to increase tension or by lowering pin to lessen tension. Loosen lock nut and lock screw at hold-open pin support and adjust pin by turning pin in or out of the threaded support (fig. 10). It is important that there be no play in the door when it is positioned on the hold-open pin and the operating lever is in the locked position. Adjust tension to proper tightness and lock hold-open pin in place by tightening set screw and lock nut.
Note. Be sure hold-open pin is turned so that locking screw contacts the flat side of the pin.
157. Bulkhead Doors
The bulkhead doors are made in two sections (fig. 13). The bottom or lower half of the door may be slid up or down by releasing the handle on the front of the door. This door can be locked in any position by opening door the desired amount, and then pushing down on latch. The top half of complete door is removable for the purpose of cleaning out leaves, twigs, or other foreign matter from the front of the radiator cores. To remove doors, raise the two spring levers at the top and allow doors to tilt forward. Raise levers to clear stops on doors, swing door to approximately 90° from bulkhead and remove from bottom retainer.
158. Protective Pads
a. General. The protective pads which can be replaced by personnel of the using arms are the periscope pads, final drive propeller shaft knee pads, controlled differential hand guard pads, and the crash pads around the door openings.
b. Periscope Pads. Working in driver’s seat, remove two screws and washers holding periscope pad to holder and remove pad. To install pad, place it on holder and install two mounting screws and lock washers.
c. Final Drive Propeller Shaft Guard Knee Pads. Remove four screws and lock washers holding halves of guards to brackets mounted on controlled differential and final drive housing. Remove three nuts and washers holding knee pad to lower guard and remove pad. To install pad, place three studs on knee pad through slots in guard and install nuts and washers. Place upper and lower half of guards on mounting brackets and install screws and washers.
d. Controlled Differential Hand Guard Pad. Remove screw and washer holding top of guard to final drive propeller shaft guard mounting boss on controlled differential. Remove bottom screw hold
254
ing guard to differential case. Slide guard out from between mounting boss on differential case and final drive propeller shaft guard mounting bracket. Remove four nuts and washers holding hand guard pad to support and remove pad. To install pad, place studs on pad through holes in support and install nuts and washers. Place support over mounting holes on controlled differential and install screws and washers.
e. Driver’s Door Opening Pad and/or Seal. Working in driver’s seat, remove 12 screws holding driver’s door opening pad retainer to under side of hull roof. Push pad downward into vehicle. This pad is pressed into position so that it will hold the weather seal into position on the reflector around door opening. To remove weather seal, pull from retainer. To install, coat edges of rubber weather seal with nonvulcanizing rubber cement, and place around door-opening deflector. Place seal in position, and raise pad tightly up against weather seal. Install 12 screws and washers holding pad and seal in position in door opening.
159. Seats
a. Removal. Remove seat back by pulling straight up until frame post of back slides out of seat assembly. Remove seat cushion. Raise seat to the UP position by releasing control lever on right side, and at same time take weight off seat. Remove four screws and washers holding seat assembly to hull floor. Remove seat through driver’s door opening.
5. Installation. Lower seat assembly through driver’s door opening, and position over tapped holes in hull floor. Adjust seat in its slotted holes, and tighten screws. Place seat cushion on seat, and slide seat back into holes on seat frame.
160. Drain Valve
a. Description. There are nine hull floor drain valves located at various places on the hull floor (fig. 26). To allow water to drain from the hull floor, push down on knob to compress spring and turn knob one-quarter turn to right. This will lock valve in the open position. After water has drained, turn knob to left to release lock and close valve.
5. Removal. With helper holding heads of bolts from underneath the vehicle, remove four safety nuts and allow valve assembly to drop down.
c. Installation. Coat edges of valve cage with joint sealing compound, and hold in position from bottom of hull. Coat four bolts with sealing compound, and push in from bottom of hull. With helper holding heads of bolts, install four safety nuts. Wipe off surplus sealing compound.
255
U-BOLT CLAMP NUTS
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Mk’^z BRAKE PIVOT
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BRAKE LEVER Vz'
z RA PD 338638
Figure IJfG. Winch—front right view.
if/ U-BOLT CLAMP
DRUM GEAR / «' I
\ i
\n. ' dF* . / \ WINCH DRUM
LOCKING PAWL , . « ✓
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CRANKSHAFT GEAR CRANKSHAFT
RA PD 338648
Figure 1.1/7. Winch—rear left view.
256
161. Vision Devices
Periscopes. The only periscopes in the hull are in the driver’s doors. These periscopes have a traverse of 360°, an elevation of 25°, and a depression of 25° from horizontal. Operation of these periscopes is covered in paragraph 22.
162. Winch
a. Description (figs. 146 and 147). A single speed, brake and pawl controlled, hand operated winch is mounted on a bracket in the right rear of the howitzer compartment. The winch is provided to lower and raise the platform and spade assembly. Two cranks are provided to operate the winch, which may be operated from the howitzer compartment or the right side of the vehicle.
b. Data.
Manufacturer------------------Sasgen Derrick Co.
Model_________________________R 100.
Type--------------------------Hand-operated.
Location---------------------- Right rear gunner’s compartment.
c. Removal. (1) Lower spade. Lower the spade assembly as a safety precaution. If it is not convenient to lower the spade assembly be sure it is securely held in its closed position by the two toggle locks.
(2) Disconnect cable from winch drum. Disengage locking pawl. Pull out cable from winch drum until ll-bolt clamp is accessible. Remove two nuts and U-bolt clamp from side of drum gear, freeing cable end. Then remove cable.
(3) Disconnect winch from, mounting bracket. Remove four nuts, lock washers and bolts from the base of winch and lift winch from mounting bracket.
d. Installation. (1) Install winch on mounting bracket. Place winch in position on mounting bracket. Secure base of winch to mounting bracket with four bolts, lock washers, and nuts.
(2) Connect cable to winch drum. Turn winch drum until U-bolt clamp holes are at top of winch drum. Feed end of cable under winch drum from rear, bringing cable over drum so that end of cable is toward rear of vehicle. Place U-bolt clamp over end of cable and through holes in drum gear. Hold U-bolt clamp and cable in position and secure with two nuts.
163. Winch Brake Band
a. Description (fig. 146). The brake band is a %-inch wide steel band, slotted at the ends. A brake band lining is secured to the brake band with brake lining rivets. The lower end of the brake band is fastened to the lower end of the brake lever. The upper end of the brake band is connected to the brake lever directly above the pivot shaft.
257
Movement of the brake lever toward the rear of the vehicle causes the brake band to contract around the brake drum sheave.
b. Data.
Inches
Length. __________________________________________________ 17
Width______________________________________________________ 3^
Thickness__________________________________________________ % 6
c. Removal. Remove cotter pins from the brake lever at both ends of brake band and remove brake band from winch.
d. Installation. Place brake band in position over brake drum sheave. Secure each end of brake band to lower end of lever with a cotter pin.
164. Winch Cable
a. Description (fig. 148). A 43-foot length of %-inch cable is connected to the inner side of the winch drum gear. The cable is strung through three flexible mounted pulleys and anchored at the top front side of the spade.
b. Removal. Lower the spade assembly as a safety precaution. If it is not convenient to lower the spade assembly be sure the spade assembly is securely held in its closed position by the two travel locks. Disengage locking pawl on winch and pull cable out from winch drum until U-bolt cable clamp is accessible. Remove two nuts and
PULLEY
' 'W^T'K.WINCH i ': ■ '\ \ zfc sEy**'•»«-;.IsfWs S. .Ml ■ _______________________________J
ifoi Ri O a .a platform
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SPADE
/ r S Bt ' ■ f - r HL-EA k
CABLE CLAMPS / X
THIMBLE PULLEY RA PD 338640
Figure 148. Winch—cable and spade assembly.
258
U-bolt from side of drum gear freeing cable end. Pull cable through the three flexible mounted pulleys and free the cable end from the thimble attached to the top left front side of spade by removing the six nuts, three clamps and three U-bolts, securing loop end of cable.
c. Installation. Loop cable end around thimble at front top left side of spade and secure cable end to cable with three U-bolts, three clamps and six nuts. String free cable end through pulley on left rear side of vehicle, through the pulley on left front top side of spade and across front side of spade through pulley on front top right side of spade. Position U-bolt holes in side of cable drum gear at top of winch drum. Feed end of cable under winch drum from rear, bringing cable over drum so that end of cable is toward rear of vehicle. Place U-bolt clamp over end of cable and through holes in side of drum gear. Hold U-bolt and cable in position and secure with two nuts.
165. Gunner’s Platform
a. Description (fig. 148). The gunner’s platform is hinged at the bottom to mounting brackets on the hull at the rear of the vehicle. Lowering and raising the platform is controlled by the movement of the spade. Brackets on each leg of the spade are provided to hold the platform when in the lowered position.
b. Removal. Lower spade and platform to the ground position (par. 19&). Remove the spring pins from the inward side of the two platform hinge pins. Drive the hinge pins toward the outside of vehicle far enough to free platform hinge eyes. Remove platform from vehicle.
c. Installation. Hoist platform and lower into position so that hinge eyes aline with bracket eyes. Drive hinge pins in position and secure hinge pins with spring pins.
166. Spade
a. Description (fig. 148). The spade is hinged to brackets mounted on the hull at the rear of the vehicle. The spade is provided to hold the vehicle in position while firing the howitzer.
b. Removal. Lower spade and platform to the ground (par. 19&). Remove platform (par. 165Z>). Attach hoist to front end of spade. Remove six nuts, three clamps, and three U-bolts holding end of cable and pull cable through the pulleys on rear of vehicle and spade. Remove nut, lock washer and bolt from front end of each spade leg, freeing hinge pins. Remove hinge pins and lower front end of spade to ground.
c. Installation. Hoist spade and lower into position so that the hinge eyes aline with the bracket eyes. Drive hinge pins in position
259
and secure hinge pins with bolt, lock washer, and nut. Pull free end of cable through pulley on top right front side of spade, through pulley on top left front side of spade and through pulley on left rear of vehicle. Loop end of cable around thimble on left front side of spade and secure cable end to cable with three U-bolts, three clamps, and six nuts. Remove hoist.
Section XXXIV. FIRE EXTINGUISHER
167. Fire Extinguishers
a. Removal. The fixed fire extinguisher, with valve assembly, can be removed as indicated below.
(1) Back off union nut that holds main tube to extinguisher (fig. 149).
(2) Back off nut holding remote control assembly to extinguisher valve.
(3) Remove eye bolt nuts holding clamps in position on extinguisher.
(4) Lift extinguisher and valve assembly out of vehicle.
5. Installation. (1) Position extinguisher and valve assembly on mounting bracket.
(2) Line up control assembly to extinguisher valve and tighten nut securely.
(3) Position main tube on extinguisher and tighten union nut.
(4) Pull holding clamp ends together and draw up eye bolt nuts securely.
REMOTE CONTROL ASSEMBLY
UNION NUT
LEAD TUBE
FIXED FIRE EXTINGUISHER CYLINDER
EYE BOLTS
RA PD 331949
Figure 149. Fixed fire extinguisher.
260
c. Handling. (1) Any cylinder containing gas under high pressure is as dangerous as a loaded shell. The extinguisher cylinders should never be dropped, stuck, handled roughly, or exposed to unnecessary heat.
(2) Red safety blow-off seal on valve head indicates whether cylinder has been discharged due to high temperature. Seal should be examined regularly; if it is missing, the cylinder should be replaced.
261
PART FOUR AUXILIARY EQUIPMENT
Section XXXV. GENERAL
168. Scope
Part Four contains information for the guidance of personnel responsible for operation of this equipment. It contains only the information necessary to using personnel to properly identify, connect, and protect such auxiliary equipment while being used or transported with the main equipment. Detailed instructions on this equipment are contained in separate technical manuals.
Section XXXVI. ARMAMENT
169. Scope
Section VII contains information required by the using arms to identify and operate the 155-mm. howitzer Ml in the 155-mm. howitzer mount M14. For preventive maintenance, malfunctions and corrections, disassembly, assembly, and general maintenance of the 155-mm. howitzer, refer to TM 9-331. For lubrication instructions, refer to section XIII of this manual.
170. Characteristics
a. The armament of the 155-mm. howitzer motor carriage M41 is employed against emplaced battery and other ground objectives. The 155-mm. howitzer mount M14 for the weapon is located in the fighting compartment at the rear of the howitzer motor carriage (figs. 1, 2, 150, and 151).
b. The 155-mm. howitzer Ml is a medium-barreled weapon using separate-loading ammunition. It is equipped with a manually operated breech mechanism and a percussion-type firing mechanism. The howitzer has a range movement in elevation of — 5° to +45° and a traverse range of 37°, right 20°, and left 17°. It is equipped with recoil mechanism M6B1 of the variable recoil, hydropneumatic type. The length of recoil varies from 60 inches at 0° to 25° elevation to 41 inches at 40° to 65° elevation. Elevation and depression of the muzzleheavy weapon is assisted by spring-type equilibrators.
262
Figure 150. 155-mm. howitzer motor carriage NL\1—right front view—howitzer in firing position.
Figure 151. 155-mm. howitzer motor carriage M.'/l—left rear view—howitzer in firing position.
263
171. Differences Among Models
There are no differences among models which will affect troop use or care of the armament.
Section XXXVII. ARMAMENT OPERATING INSTRUCTIONS
172. Placing Weapon in Firing Position
a. Unlock the tube traveling lock by loosening the nut which secures the upper half of the traveling lock. Rotate the upper half up and off the tube; then elevate tube slightly in order to push traveling lock down in position on the hull (figs. 159 and 160). Remove howitzer covers and store them out of way in their proper place.
6. Release the traverse locks in the firing compartment (fig. 158).
c. Place spade in firing position. Free the support arms of the spade assembly by disengaging the spade latches. Release winch gear locking pawl and operate the brake lever to lower spade to ground. Pulling the winch brake lever toward the rear applies the brake; pushing the lever toward the front releases the brake (fig. 161). Back up vehicle to force spade prongs into ground. When in its proper position, the spade must be flush with the ground and the spade stops seated against the hull. Apply vehicle steering brakes and lock in position.
FIRING MECHANISM BLOCK HANDLE RA PD 63217
ARM STOP
Figure 152. Removing firing mechanism Ml.
264
FIRING MECHANISM Ml-
PERCUSSION HAMMER .
7.
173. Inspection Before Firing
a. Prior to firing, inspect the bore and breech to see that no dirt or foreign matter has accumulated. If there is foreign matter in the bore, clean the bore thoroughly and wipe it dry. Normally, the bore should be wiped or cleaned with rifle bore cleaner to remove the coating applied after the previous firing.
BREECH OPERATING LEVER CLOSING LATCH
RA PD 63218
FIRING MECHANISM HOUSING
Figure 153. Releasing breech operating lever closing latch.
Figure 154- Unsealing breech.
265
-BREECHBLOCK ROTATING CAM
--BREECHBLOCK DRIVER
| ROLLER
b. Check the replenisher and recuperator to make certain that there is sufficient oil in the recoil and recuperator cylinders. Refer to TM 9-331.
c. Inspect to see that there is no leakage of oil, that the bearing surface of the howitzer tube is well lubricated, and that the piston rod nuts are properly tightened.
d. For bore-sighting weapon, refer to paragraph 182.
174. To Traverse
The traversing handwheel is located on the left side of the carriage, ahead of the elevating handwheel (fig. 156). One complete turn of
Figure 155. Breech mechanism open.
the handwheel in a clockwise direction traverses the carriage to the right approximately 10.3 mils (34.7 minutes). The range of traverse is 37° or 17° to the left and 20° to the right of midposition. Approximately 64 turns of the handwheel are required to traverse the mount from one side to the other of its range of traverse.
175. To Elevate
The elevating handwheel is located at the left rear of the carriage in back of the traversing handwheel (fig. 156). One complete turn of the handwheel in a clockwise direction elevates the weapon approximately 10 mils (33 minutes). The range of elevation is 1,156 mils (65°). Approximately 78 turns of the handwheel are required to elevate the weapon from 0° to 65°.
266
INTERRUPTED THREADS ON BREECHBLOCK
V——'
X INTERRUPTED THREADS IN BREECH RING
176. Operating Breech Mechanism
a. To Open Breech. Remove firing mechanism Ml (fig. 152). With the left hand, release the operating handle latch, while with the right, pull the breech operating handle backward and downward until it contacts its stop on the breechblock carrier (figs. 153 and 154). Then swing the breech operating handle in a horizontal arc to the right (fig. 155).
b. Loading the Howitzer. (1) Elevate or depress the weapon to an elevation convenient for loading (between 200 and 300 mils). Remove the firing mechanism Ml and open the breech. Latch the percussion hammer in the released (down) position by means of the percussion hammer lock pin.
Caution: The percussion hammer lock pin will not be drawn from its locked position, where it interferes with the upward swing of the percussion hammer, until after the breech has been closed and locked and the piece is ready to be fired. This is a safety precaution.
(2) Swab the powder chamber and breech recess. If a charge has been fired, wipe the powder residue from the obturator spindle head with a cloth or piece of waste, slightly dampened with oil. Clean the primer vent with vent-cleaning tool (41-T-3081-120). Ream the primer seat with the primer-seat cleaning reamer (41-R-501-80). Inspect the bore for burning fragments of powder bags or other objects and for bore injuries. In night firing, swab bore with water.
(3) Prepare projectile. Verify the type, weight, and lot number, and examine carefully for defects. Remove the grommet and inspect the rotating band with special care; remove any burs with a file. Clean the entire surface of the projectile with a dry piece of waste or cloth. Sand or dirt on the projectile might cause premature detonation when the piece is fired and will cause undue wear on the bore.
(4) Fuze projectile. Unscrew the eye bolt lifting plug from the fuze socket. Insert the designated fuze, being careful that it is fitted with its felt or rubber washer. Screw it home by hand. Give the fuze its final seating with fuze wrench M7A1 (41-W-1596-50). No great force should be used. If there is any difficulty in screwing the fuze home, the fuze should be removed and another inserted. If the same trouble is encountered with the second fuze, the shell should be rejected. Set the fuze. (See par. 186.)
(5) Load projectile. Bring up the prepared projectile on the loading tray (C73641). In carrying the loading tray, grasp the handles and raise it with the front slightly above the rear. Get a firm grip on the handles, as a shell may be dropped easily if the tray is not carried in the proper position. Place the lip of the tray in the breech recess. Place the loading rammer head (B108585) squarely against the base of the projectile, pushing the projectile carefully until it has
267
cleared the threads of the breech recess. Exercise extreme care that the fuze does not come in contact with anything.
(6) Rami projectile. Ram the projectile home with a powerful stroke. It is important that projectiles be rammed home with a uniform force since variations in the ramming force will cause slight variations in range. It is also important to avoid damage to the rotating bands on the projectile as such damage is likely to cause erratic flight of the projectile.
(7) Prepare propelling charge. For description and preparation for firing of the propelling charge, see paragraph 1856. Bring the prepared propelling charge up to the breech immediately after the projectile has been rammed.
Caution: An exposed propelling charge will not be near the weapon at any other time.
Figure 156. Controls and sighting equipment.
268
TELESCOPE MOUNT M25
PANORAMIC / . X
TELESCOPE \ ■ j
M12A6 \ JE j ? I
TRAVERSING HANDWHEEL ELEVATING HANDWHEEL
(8) Load propelling charge. Place the charge in the chamber with the igniter end to the rear, and push it in until the base of the charge is flush with the rear end of the chamber. The igniter pad must come directly in front of the vent when the breech is closed to insure ignition of the charge.
Note. To insure intransmission of the flash from the primer to the charge, the obturator spindlehead should come in contact with the base of the charge when the breech is closed, must push the charge forward to its final position, and must remain in contact with it.
c. To Close Breech. Swing the operating handle lever in a horizontal arc to the left. When the breechblock driver roller enters the breechblock rotating cam, raise the operating handle lever upward and forward until the operating handle latch latches the lever.
Figure 157. Inserting primer.
177. To Fire
a. Insert a percussion-type primer in the firing mechanism, Ml (fig. 157). The primer case is inserted into the primer holder by pressing the head of the case downward firmly against the firing pin guide so that the rim of the case slides under the edges of the slot in the primer holder. The primer is then held in position by the pressure of the firing spring.
b. In inserting the primer in the primer holder, the primer should be held in such a manner that no part of the hand is in front of the wad end of the primer. This precaution must be taken to avoid a severe burn in the case of premature discharge of the primer.
c. Should the primer be slightly oversize or the primer holder dirty, the primer will stick before it is properly seated. Force should not be exerted. Remove the primer and clean the primer holder, or insert another primer.
d. Insert the firing mechanism in the firing mechanism housing, taking care that the front end of the primer has entered the obturator spindle plug. Seat the mechanism by turning the firing mechanism
752022 0—47-----18
269
WrA PD 63277
Wju vw- - • w-r :: '
handle in a clockwise direction until it has contacted the firing mechanism block handle arm stop and has been latched. If the mechanism will not seat properly, the primer may be oversize, or its seat in the plug or in the primer holder may be dirty, or the breech may not be fully closed.
Caution: Make certain that the firing mechanism Ml is screwed home and is latched in position.
e. Attach the lanyard. Draw the percussion hammer lock pin to the left and out of the path of the hammer, turning the percussion hammer lock pin knob to place the pin in locked-out position.
/. Grasp the handle of the 4-foot lanyard (21-L-123-725) with the right hand, and without raising the hand, pull with a quick, strong pull (not a jerk) prolonged sufficiently to ensure the percussion hammer hitting the firing pin. The lanyard will be pulled from a position as near the rear of the piece as is convenient, and sufficiently out of the line of recoil to ensure safety.
g. If the long, 50-foot lanyard (21-L-106) is used, it will be attached immediately before, and detached immediately after, the round is fired.
178. To Unload
a. Service Rounds. Whenever possible, live, fuzzed projectiles are to be unloaded from the piece by being fired out of the weapon. Where conditions do not permit the firing of the weapon, the round is to be removed with the cleaning and unloading rammer head M7 (C57112). Depress the weapon to zero elevation, and with the loading tray in position in the breech, insert the rammer head into muzzle of howitzer. Then ram the round out of the howitzer onto the loading tray. This operation must be done by or under the personal supervision of the battery commander.
6. Dummy Projectile. To unload the dummy projectile, lower the weapon to zero elevation. Pull out the dummy charge and, with the loading tray in place, remove the projectile with the hook-type extractor (72—1—5, type C). Insert the extractor in the base of the projectile, hook it against the shoulder of the recess, and pull the projectile out of the howitzer onto the loading tray. If the extractor is not available, the projectile may be removed by use of the cleaning and unloading rammer head, M7. This operation is performed from the muzzle end of the weapon.
c. To Remove a Fuze From a Shell. If, for any reason, a projectile which has been fuzed is not to be fired, the fuze will be removed. Reset the fuze to “SAFE,” if so designed. Start the unscrewing operation with fuze wrench M7A1; complete the unscrewing of the fuze by hand.
Caution: If the adapter starts to unscrew with fuze, the unscrewing operation must be stopped at once and the shell disposed of as directed by the officer in charge.
270
Figure 158. Traverse locks.
Figure 159. Tube traveling lock in locked position.
271
I—-TRAVELING LOCK
MUZZLE
I COVER
RA PD 86917
M ....W
traverse locks'
Figure 160. Tube traveling lock in unlocked position.
LOCKING PAWL 1 I /J|
\ LI ft fif
GSSjQ BRAKE LEVER \ / 7QI
“““Tsl \ \ Bl y 4 S r ? S
/ % WINCH DRUM \ \ /
CRANK U \ Wi / I
% \ / -1
MH
WINCH DRUM GEARXwWMkcMB MV '1
MOUNTING BOLT—
HHX z ’"y
X;-. ' -—. t •-, ~Tjt: ■ ■; ■ "
L '?f/ / F bij J CRANK
i III *: ‘ :; ~ ' ' ’-F /
f1I b ] •
Ki ^r»Z
RA PD 338641
Figure 161. Spade winch.
272
GUNNER’S PLATFORM ADJUSTABLE LEVER
■ I
fi^Ti oHmF |fiC
—* HF
ARM '
i '
■W I
(yf ■ ksL'k^sX'
,J|ft './ |\ ’RA PD_e6910
GUNNER’S PLATFORM
Figure 162. Gunner’s platform adjustable lever in traveling position.
179. To Place in Traveling Position
a. Fix Tube Position. Bring the weapon to a horizontal position in the center of traverse. Insert the traverse locks in the brackets on traverse ring, and tighten wheel nuts securely (fig. 158).
b. Clean and Oil Gun. Clean, thoroughly dry, and cover the bore, powder chamber, breech recess, breechblock, and firing mechanism with a coat of specified lubricant; oil the top and bottom carriages (mount). Lock the percussion hammer in traveling position.
c. Stow Tools, Equipment, and Ammunition. Return sighting equipment, firing tools, and accessory equipment to their proper stowage position in chests, in brackets, and in clips on the vehicle. Store the ammunition, and close and store the powder containers.
d. Install Howitzer Covers. Install the breech, muzzle, and sight mount covers.
e. Fasten Traveling Lock (figs. 12 and 13). Swing traveling lock up to a vertical position. Clamp upper half of lock around tube. Tighten nut.
273
f. Raise Spade. Move the vehicle forward to free the spade from the earth. Crank up spade winch (fig. 161), and lift spade to traveling position. As the spade approaches a vertical position, push the gunner’s platform against the rear of the fighting compartment and raise the gunner’s platform adjustable lever (fig. 162) so it will hold the platform in place when the spade is secured (fig. 162). Secure the support arms of the spade assembly by engaging the spade latches.
Section XXXVIII. SIGHTING AND FIRE CONTROL EQUIPMENT
180. Characteristics
The sighting equipment for the 155-mm. howitzer mount M14 (T19) is the telescope mount M25 which supports the panoramic telescope M12A6. The equipment is intended primarily for indirect fire, but may also be used for direct fire to a maximum range of 2,000 yards. A gunner’s quadrant may be used with the equipment to obtain “pin point” accuracy in indirect fire.
,..^1
WING KNOB ...... TELESCOPE HOLDER
LONGITUDINAL
LEVEL S ’ ■%> CROSS LEVEL Jb
r/
7 zdB* ■ W
• ' lbracket
QUADRANT iSX' •^7%
SEAT .. jFjSL
W*. MT ELEVATION KNOB
> ' <•
/Xj \ C- ELEVATION MICROMETER
C ELEVATION SCALE
CROSS LEVELING KNOB RA PD 55600
Figure 163. Telescope mount M25.
274
181. Telescope Mount M25 and Panoramic Telescope M12A6
a. The telescope mount M25 (fig. 163) is provided with a telescope socket for supporting the panoramic telescope. To install the telescope, turn the wing knob on the telescope socket against spring pressure, and then lower the panoramic telescope into position, alining its lug between the tangent adjusting screws at the front of the socket. Exert a slight downward pressure on the telescope to insure a full seating.
b. Levels and control knobs are provided for longitudinal leveling and cross-leveling. Cross-leveling introduces an azimuth correction to compensate for errors caused when the weapon is elevated with the trunnions out of level. The longitudinal level is used in setting elevation. Elevation in mils is set on the elevation scale and micrometer, and the howitzer is then elevated or depressed to center the longitudinal level bubble. Finer elevation settings (0.2-mil intervals) can be made by using a gunner’s quadrant on the quadrant seat.
c. Tangent screws are provided on the telescope socket for adjusting the line of sight of the panoramic telescope M12 in azimuth. The elevation scale and micrometer are adjustable to read zero simultaneously when the howitzer is leveled longitudinally (axis of bore), and the longitudinal level is centered.
d. The line of sight of the panoramic telescope (fig. 164) is moved in azimuth by the azimuth worm knob. A throw-out lever, when depressed, permits rapid motion of the azimuth worm. The azimuth scale (100-mil intervals) is supplemented by the azimuth micrometer (10-mil intervals). The micrometer index or gunner’s aid can be set for deflection right (R) or left (L) on the deflection scale.
e. The telescope reticle pattern (fig. 165) contains a pair of cross lines used for indirect fire and a set of range graduations used for direct fire. Range numerals are in hundredths of yards, with the last two ciphers omitted. Range graduations are calibrated for 155-mm. HE shell M107, charge 7. Each horizontal line or space represents a deflection of 5 mils.
f. Instrument light M34 is used to illuminate the scales, levels, ana reticle for night operation.
g. To lay the howitzer for indirect fire, proceed as follows: Set the target azimuth on the azimuth scale and micrometer of the panoramic telescope, introducing deflection if necessary by moving the micrometer index. Set the required elevation on the elevation scale and micrometer of the telescope mount. Cross-level the mount and keep it cross-leveled during the remaining operations. Traverse the howitzer to bring the vertical cross line of the telescope reticle on the aiming point and elevate or depress the howitzer to center the longitudinal level bubble. (It may be necessary to turn the elevation knob on the panoramic telescope to bring the aiming point into the field of view.
275
EL EVATION MICROMETER
ELEVATION KNOB
ROTATING HEAD
AZIMUTH WORM THROWOUT LEVER
EYE SHIELD
OPEN SIGHT
COARSE ELEVATION ZERO GRADUATION
Figure 161,. Panoramic telescope M12A6.
AZIMUTH MICROMETER
(AZIMUTH SCALE ^CLAMPING RING
AZIMUTH SCALE
AZIMUTH SCALE INDEX
(azimuth WORM (Knob
MICROMETER INDEX
DEFLECTION
RA PD 96179
276
This operation is permissible in indirect fire.) The howitzer is now laid in elevation. When a higher degree of accuracy is required, continue the operation by placing an accurately set gunner’s quadrant on the quadrant seat and rotating the howitzer elevating handwheel to center the level bubble in the quadrant.
h. To aim the howitzer for direct fire, proceed as follows: Set the elevation knob on the panoramic telescope to zero elevation by matching the coarse zero graduation and the micrometer zero graduation against their indexes. Set the azimuth scale, micrometer index, and
Figure 165. Reticle pattern for panoramic telescope M12A6.
J
micrometer to zero. Set the elevation scale and micrometer on the telescope mount to zero. Cross-level the mount and keep it crossleveled during the remaining operations. Using the howitzer traversing and elevating handwheels, bring the target to the required range and deflection on the telescope reticle.
182. BoreSighting
a. The purpose of the bore-sighting operation is to test the aline-ment of the sighting equipment for parallelism with the bore of the howitzer. For expediency, it may be performed by sighting on a well-defined object at least 1,500 yards distant.
5. Open the breech of the howitzer, place bore sights in the tube, and, while looking through the tube, aline the howitzer on the distant object. With the telescope in position in the mount (azimuth scale set at zero), observe through the eyepiece and note the position of the cross lines with respect to the distant object or aiming point. If they do not coincide with the distant object or aiming point, move the line of sight, as follows: Loosen the headless lock screws in the telescope socket and adjust the tangent screws until coincidence is obtained; tighten the headless lock screws.
277
RA PD 55456
Figure 166. Periscope M6.
278
BODY SPRING ■—---> ECCENTRIC ASSEMBLY-
183. Periscope M6
a. The periscope M6 (fig. 166) is used by the driver and assistant driver for observation from the interior of the vehicle. The periscope is secured in a holder by a latch mechanism and a locking knob. The head is constructed of plastic material so it will shatter into small pieces if struck by a projectile.
b. To remove the periscope from the holder, open the latch on the front of the holder and loosen the locking knob on the front of the periscope. Pull the periscope straight out of the holder.
c. The heads are readily replaced with the spare heads which are provided. To remove the head from the periscope body, turn the two eccentric assemblies located on the sides of the periscope body until the head clamp is completely disengaged from the latches of the eccentric mechanism. Lift the head from the periscope body. When replacing the head, position it on the top of the periscope body with the window facing the front side of the periscope. Turn the eccentric assemblies until the reference arrow on each eccentric matches the corresponding arrow on the periscope body. See that the handles of the eccentric mechanisms lie flat on the sides of the periscope body.
d. To operate the periscope, grasp the sides of the periscope and rotate, elevate, or depress the holder and periscope until the desired panorama is brought into the field of view.
Section XXXIX. AMMUNITION
184. Authorized Rounds
Authorized rounds for the 155-mm howitzer Ml are listed in table I on page 283 and illustrated in figures 167, 168, and 169. It will be noted that standard nomenclature, which completely identifies the ammunition, is used in the listing. Identification is provided for by painting and marking on each of the components and on packing in accordance with the basic scheme described in TM 9-1900. In addition to the projectile, charge, and fuze listed in table 1, the Mk2A4 percussion primer is required for each complete round.
185. Preparation for Firing
a. Projectiles. Aside from removal of grommet and lifting piug, it is only necessary to fuze those shells which are shipped uncrated and unfuzed.
b. Propelling Charges (figs. 170 and 171). After the charge has been removed from its moistureproof container, it is only necessary to remove the igniter protector cap and data tag. The charge must be loaded into the weapon with the igniter (cloth dyed red) toward the breech. When it is desired to fire less than the full charge, remove the undesired increments.
279
c. Primer (fig. 172). To prepare a primer for firing it is only necessary to insert it into the firing mechanism.
KIND OF FILLER-------
(CALIBER AND /TYPE OF CANNON
Figure 169. BE, HC smoke shell M116.
280
LOT NUMBER---- /TYPE OF CANNON
A I C SYMBOI____ MODEL OF SHELL-] (WEIGHT ZONE
| /MARKING
*---------OLIVE DRAB (MARKING IN YELLOW)-----------*■
-»------------------26.81 APPROX
RA PD 26800
Figure 167. HE shell M107.
_ \CALIBER AND /TYPE OF CANNON
LOT NUMBER-. -------------------- KIND OF FILLER
MODEL OF SHELL-.
A I C.-SYMBOL GREEN BANDS ---jzONE
[MARKING
rl 'i SlfcJ I J paw
He R5
i k tJi ..............n
h------------------GRAY (MARKING IN GREEN)------------*
k-------------------------26.78 MAX.---------------------'»l
RA PD 26801
Figure 168. H persistent gas shell MHO.
LOT NUMBER AND LOADER'S INITIALS-] ICALIBER AND
MODEL OF SHELLq F |TYPE OF CANNON
YELLOW BAND] r~ KIND OF FILLER
A.I.C. SYMBOL
(MARKING IN YELLOW)---------------
I—-----------------------26.78 MAX-------------------------—‘
RA PD 26802
Figure 170. Green bag propelling charge M3.
186. Fuzes
a. PD Fuzes, M51,M51A1,M51A3, or M51A4.* (1) General. The fuzes and boosters making up these assemblies are essentially the same in principle, but differ in various respects due to modifications of either the fuze or the booster, as follows: The M51A1 differs from the M51 only with respect to the booster; the M21A1 booster has a 14-inch flash hole in its rotor cover as compared with a %-inch flash hole in the M21 booster. In the M51A3 and M51A4, the delay action is further modified to provide for a 0.15-second delay instead of 0.05-second as in the earlier models. The M21A1 booster assembled to the M51A3 fuze is also a modification of the earlier boosters, adding a set-back pin for additional insurance against premature or accidental functioning. The M21A4 is a further modification of the M21A2.
(2) Description. In all of the fuzes (fig. 173), the booster is permanently attached to the fuze at the time of manufacture. Thereafter, the fuze with booster is handled as a unit. The fuze contains two actions, superquick and delay. Although both actions are initiated on impact, the functioning of the shell depends upon the setting of the fuze. When the fuze is set DELAY, the superquick action is so interrupted that the projectile functions with delay action. It should be noted, however, that if the superquick action malfunctions when the fuze is set SQ, the projectile will function with delay action rather than become a dud. On the side of the fuze near the base is a slotted “setting sleeve” and two registration lines; the one parallel to the axis is marked SQ, the other DELAY. As shipped, the fuze is set SQ. To set the fuze for delay action it is only necessary to turn the setting sleeve so that its slot is alined with DELAY. A delay pellet, 0.15-second in the M51A3 and M51A4, and 0.05-second in the M51 and M51A1 fuzes, incorporated in the delay action trail provides for the delay action. The setting may be made or changed at will with a
*PD fuzes, M51, w/boosters M21 or M51A1, w/booster M21A1, are authorized for emergency combat only and must be drop-tested before use. PD fuzes M51 or M51A1, w/booster, M20A1 are authorized for service and practice use until supplies of fuzes M51A3, w/boosters M21A2 and M51A4, w/boosters, M21A4 become available.
281
•--------------------19. MIN. 21. MAX.------------------
Jg fit . ■ I
& 'W ** J |
»’??«!)' ICHRRGEM4MiIi Ji jj JTl ]f
«............. alL .JJ L. .J:l L. . ..
Mb jJLjilS.t.
RA PD 97730
Figure 171. White bag propelling charge M4A1.
screwdriver or some other similar tool any time before firing, 1 his can be done even in the dark by noting the position of the slot, parallel to the fuze axis for superquick action, at right angles thereto for delay.
( A cotter pin with pull ring is assembled to the booster to prevent
[£ accidental movement of the detonator during shipment. This cotter
J pin is to be withdrawn just prior to assembling the fuze with booster
* to the projectile.
t (3) Preparation for firing. To fuze the projectile, proceed as
follows:
J (a) Remove eye bolt lifting plug from projectile.
a (5) Inspect fuze cavity and threads. They should be free of foreign
matter which would interfere with the proper assembly of the fuze.
(
Fig.
No.
Piojectile
Fuze for which adapted
Propelling charge
GAS
168
167
SHELL, gas, persistent, CNS, MHO, for 155-mm. howitzer, Ml.
SHELL, gas, persistent, H, Ml 10, for 155-mm. howitzer, Ml.
SHELL, gas, persistent, H, M105, for 155-mm. howitzers, M1917-18.2
SHELL, gas, persistent, H, Mk2Al, for 155-mm. howitzers, M1917-18.2
SHELL, gas, persistent, CNS, Mk2Al Mod. 1, for 155-mm. howitzers, M1917-18.2
SHELL, gas, persistent, H, Mk2Al Mod. 1, for 155-mm. howitzers, M1917-18.2
HIGH EXPLOSIVE
SHELL, HE, M107, for 155-mm. howitzers.
SHELL, HE, M107 w/suppl chg, for 155-mm. howitzer, Ml.
SHELL, HE, M102, for 155-mm. howitzers, M1917-18.2
SHELL, HE, MklAl, for 155-mm. howitzers, M1917-18.2
SHELL, HE, M107, adapted for fuze, VT, T76E6, for 155-mm. howitzer, Ml.8
(FUZE, PD, M51 series.3
FUZE, PD, M51 apripc 3
FUZE, ’ TSQ, M55 qpripa 5
FUZE,' time, mechanical, M67 series.6 7
or
FUZE, CP, M78 (T105).
FUZE, VT, T76E6__
CHARGE, propelling, Ml Al (green bag), 155-mm. ho w., M1917A1-17A2-18;2
CHARGE, propelling, M2 (white bag), 155-mm. how., M1917A1-17A2-18;2
CHARGE, propelling, M2A1 (white bag), 155-mm. how., M1917A1-17A2-18;2
CHARGE, propelling, M3 (green bag), 155-mm. how., Ml;2
CHARGE, propelling, M4 (white bag), 155-mm. how., Ml2 4;
or
CHARGE, propelling, M4A1 (white bag), 155-mm. how., Ml24
CHARGE, propelling, M4 (white bag), 155-mm. how., Ml.
See footnotes at end of table.
283
Table I.—Authorized rounds for 155-mm. howitzer, Ml—Continued
SERVICE AMMUNITION'
Fig. No. Projectile Fuze for which adapted Propelling charge
169 SMOKE SHELL, smoke, FS, Ml 10, for 155-mm. howitzer, Ml. SHELL, smoke, phosphorus, WP, Ml 10, for 155-mm. howitzer, Ml. SHELL, smoke, FS, M105, for 155-mm. howitzers, M1917-18.2 SHELL, smoke, phosphorus, WP, M105, for 155-mm. howitzers, M1917-18.2 SHELL, smoke, FS, Mk2Al, for 155-mm. howitzers, Ml917-18.2 SHELL, smoke, phosphorus, WP, Mk2Al, for 155-mm. howitzers, M1917-18.2 SHELL, smoke, HC, BE, Ml 16, for 155-mm. howitzer, Ml. SHELL, smoke, red, BE, Ml 16, for 155-mm. howitzer, Ml. SHELL, smoke, yellow, BE, Ml 16, for 155-mm. howitzer, Ml. SHELL, smoke, green, BE, M116, for 155-mm. howitzer, Ml. SHELL, smoke, violet, BE, Ml 16, for 155-mm. howitzer, Ml. FUZE, PD, M51 series 3 >FUZE, TSQ, M54_... CHARGE, propelling, Ml Al (green bag), 155-mm. how, M1917A1-17A2-18 2; CHARGE, propelling, M2 (white bag), 155-mm. how, M1917A1-17A2-18 2; CHARGE, propelling, M2 Al (white bag), 155-mm. how, M1917A1-17A2-18 2; CHARGE, propelling, M3 (green bag), 155-mm. how, Ml 2; CHARGE, propelling, M4 (white bag), 155-mm. how, Ml 2- 4; or CHARGE, propelling, M4A1 (white bag), 155-mm. how, Ml.2’4 CHARGE, propelling, M3 (green bag), 155-mm. how, Ml; CHARGE, propelling, M4 (white bag), 155-mm. how, Ml; or CHARGE, propelling, M4A1 (white bag), 155-mm. how, Ml.
1 Other primers which may be used if PRIMER, percussion, Mk2A4 is not available are: PRIMER, percussion, Mk2A3, Mk2, Mk2A, or Mk2Al. PRIMER, percussion, Mk2Al, is restricted to use in 155-mm. howitzers only, except for certain lots. PRIMER, percussion, Mk2 and Mk2A, may be used in all authorized cannon but should be reserved where practicable for issue for cannon other than 155-mm. howitzers. See ORD II, SNL R-3.
2 Limited standard for use in 155-mm. howitzer, Ml.
3 FUZE, PD, M51, M51A1, M51A3, or M51A4. The following limitations apply to the M51 fuze, and modifications: FUZE, PD, M51 or M51A1, w/booster, M20A1, for service and practice purposes. Their use for service firing will be discontinued when a sufficient supply of M51A3 fuzes with M21A2 boosters or M51A4 fuzes with M21A4 boosters becomes available. FUZE, PD, M51, w/booster, M21, or M51A1, w/booster, M21A1, for emergency combat use only; must be drop-tested prior to use.
4 For emergency use only, when fired with M1917A1-17A2-18 howitzer projectiles.
5 FUZE, TSQ, M55, M55A1, M55A2, or M55A3. For emergency use in the absence of fuze .time, mechanical, M67 series.
6 Authorized for use with M1917A1-17A2-18 howitzer shell when fired from the Ml howitzer only.
7 FUZE, time, mechanical, M67 or M67A1, M67A2, or M67A3.
3 When supplementary charge is added to the fuze cavity, this projectile is used with FUZE, PD, M51 series, FUZE, time, mechanical, M67 series; FUZE, TSQ, M55 series, or FUZE, CP, M78.
284
Figure 174. TSQ fuze, M55A2.
752022 0—47——19
285
LOADER'S INITIALS AND LOT NUMBER
\ y MODEL OF PRIMER
iib,
/ ' ffiwnJ1J.11
\ I bMMMHMM'
\ -----1.595 MAX.------►!
YEAR OF LOADING
RA PD 69092A
Figure 172. Percussion primer Mk2A4.
SETTING SLEEVE
AS INDICATED-SET FOR SUPERQUICK ACTION, AT RIGHT ANGLES (PERPENDICULAR TO AXIS OF FUZE) FOR DELAY ACTION.
rl ||S /
I jls •
el- .^| H1 cn D
■m IB '
W i
\| "J 5 SEC." INDICATES LENGTH OF DELAY
SAFETY COTTER PIN IN BOOSTER REMOVED BEFORE ASSEMBLY TO SHELL
RA PD 15O53A
Figure 173. PD fuze, M51A4.
STAMPED ON REVERSE SIDE:] /TYPE AND MODEL OF FUZE
LOADER'S LOT NUMBER /
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MONTH AND YEAR LOADED ^/>^/MANUFACTURER S INITIALS
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(2) Preparation for firing. After assembly of the fuze to the pro* jectile and prior to firing, the safety pull wire must be withdrawn from the fuze for either superquick or time setting. To do this, pull lower end of the wire from the hole and slide wire off the end of the fuze. If superquick action is required, the graduated time-train ring can be left as shipped (set at safe (S)), or set for a time greater than the expected time of flight. If time action is required, the graduated time-train ring is set for the required time of burning by means of a fuze setter.
Note. If, after setting the fuze preparatory to firing, the round is not fired, the fuze will be reset “safe” (S) and the safety pull wire replaced in its proper position before the fuze is returned to its packing container.
c. TSQ Fuzes M55, M55A1, M55A2, or M55A3. This fuze (fig. 174) functions in the same manner as the M54, with the one exception that the M55 series is issued with booster. The bodies of both the M54 and M55 fuzes are of identical design. The boosters are of the M21 series described in subparagraph a above.
d. Mechanical Time Fuzes M67, M67A1, M67A2, or M67A3. (1) Description. The M67 and its modifications (fig. 175) are essentially alike, and are intended to provide a means of high-burst adjustment at longer ranges when firing the high-explosive shell. The primary differences occur in booster modifications as described in subparagraph a above. The fuze is of the mechanical (clockwork) time type, and is similar to the M43-type fuze in contour and in design except that the escapement mechanism has been modified to give a longer burning time. There is no impact element. The upper and lower caps are staked together and turn as a unit when setting the fuze. A set or register line is stamped on the rim of the lower cap. A safety line
inADPR’S IDT NI1MRFR (STAMPED ON REVERSE SIDE:
LOADERS LOT NUMBER^ J MANUFACTURER’S INITIALS &
X. [YEAR OF MANUFACTURE
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RA PD 97704
Figure 175. Mechanical time fuze, M67A3.
286
RA PD 97699
Figure 176. CP fuze, M78.
with S below it, and time graduations to 75 seconds with 0.5-second intervals, are stamped on the body. The graduations run counterclockwise, viewed from the point of the fuze. Two setting grooves, one each on the lower cap and body, are provided for setting the fuze. A safety feature incorporated in the fuze is designed to prevent functioning should the fuze be set for 3 seconds or less. As shipped, the fuze is set “safe.” That is, the set line in the lower cap is in alinement with the safety line S in the body. A pull wire is fitted to the fuze to secure the firing pin prior to firing. A cotter pin with pull ring is assembled to the booster to prevent accidental movement of the detonator during shipment. The booster is assembled to the fuze at the time of manufacture and handled thereafter as a single unit with the fuze, in shipment and assembly to the projectile. The cotter pin is to be withdrawn just prior to assembling the fuze with booster to the shell.
(2) Preparation for firing. To fuze the projectile proceed as follows:
(a) Remove the eye bolt lifting plug from the projectile.
(6) Inspect the fuze cavity and threads. They should be free of foreign matter which would interfere with the proper assembly of the fuze.
() If gum is present in the above parts, it can best be removed by benzol, acetone, alcohol, or a mixture of equal parts of these solvents. Deposited gum is not readily soluble in fresh gasoline. When gum has dried, it may be necessary to use mechanical means to remove it.
(c) Parts which cannot be thoroughly cleaned and freed from gum deposit without damage should be replaced.
(d} After cleaning and reassembly, fill fuel tanks half full with fresh gasoline which has not been in storage very long.
(e) Add two containers (8 ounces) of gum preventive compound to each fuel tank.
(/) Fill fuel tanks to capacity and operate vehicle for at least 5 minutes.
(5) Breech mechanism. When possible, partially disassemble breech mechanism, clean w’ith dry-cleaning solvent, and dip or brush interior parts with rust preventive compound (light). Assemble breech mechanism. Apply a coating of rust preventive compound (light) to all exterior portions of the breech.
(6) Howitzer tube. Clean bore with dry-cleaning .solvent and thoroughly dry. Swab bore with rust preventive compound (light).
(7) Sealing howitzer. Seal the muzzle and breech with two layers of grease-proof wrapping paper and one of Kraft waterproof wrapping paper. Apply nonhygroscopic adhesive tape over paper, completely sealing the openings. Apply rust preventive compound (thin film) over the tape as a sealer. If greaseproof wrapper is not available, use canvas or burlap impregnated w’ith rust preventive compound (thin film).
(8) Covers. Install muzzle and breech covers supplied with material.
(9) Exterior of vehicle. If time and facilities permit, remove rust appearing on any part of the vehicle exterior with flint paper. Repaint painted surfaces whenever necessary to protect wood or metal. Coat exposed polished metal surfaces susceptible to rust, with rust preventive compound (light). Close all door.s, hatches, vision slots, and other openings firmly. Make sure tarpaulins are in place and firmly secured. Leave rubber floor mats, when provided, in an unrolled position on the floor, not rolled or curled up. Equipment such as pioneer tools, track tools, and fire extinguishers will remain in place on the vehicle. For treatment of small arms carried on or within the vehicle, refer to pertinent technical manuals.
(10) Engine, (a) Remove spark plugs and spray into tops of cylinders with preservative engine oil (PE 30) while slowly rotating engine. Replace spark plugs.
(&) If spark plugs cannot be removed, spray preservative oil into
299
air intake with engine running at a fast idle until smoke comes from exhaust pipe.
Caution: Preservative oil must never be poured through carburetor.
After spraying preservative oil into air intake, shut off engine and allow to cool for about 15 minutes. Start engine and again spray preservative oil into air intake for several minutes only. Second spraying is necessary in order to coat exhaust valves. Do not run engine for more than several minutes as exhaust valves will become so hot that preservative oil will not adhere properly. Perform this treatment when further running of the engine is not necessary.
(