    [Technical Manual]
    [From the U.S. Government Publishing Office, www.gpo.gov]

    ﻿
    vi i.3s; 9-i^os wHb
    Document
    Reserve	TM 9-1305
    WAR DEPARTMENT
    TECHNICAL MANUAL
    GUN AND CARRIAGE, 75-MM, M1897, ALL TYPES, AND SPECIAL FIELD ARTILLERY VEHICLES
    April 20, 1942
    NON-CIRCULATING
    NTSU LIBRARY
    *TM 9-1305 1
    TECHNICAL MANUAL] No. 9-1305
    WAR DEPARTMENT, Washington. April 20, 1942.
    ORDNANCE MAINTENANCE
    GUN AND CARRIAGE, 75-MM, M1897, ALL TYPES, AND SPECIAL FIELD ARTILLERY VEHICLES
    Paragraphs
    Section I. General_____________________________________________   1
    II.	Data____________________________________________ 2- 5
    III.	Description______________________________________ 6-13
    IV.	Inspection of guns, carriages, and special field artillery vehicles___________________________________14—23
    V.	Instructions for maintenance'and repair__________24-49
    VI.	Tools for inspection_______________________________ 50
    VII.	Tools for maintenance and repair_________________51-80
    VIII.	Inspection and repair of special tools_____________ 81
    IX.	Field service modification work orders (FSMWO)_	82
    Page
    Appendix. List of references_________________________________ 155
    Index________________________________________________________ 157
    Section I
    GENERAL
    Paragraph
    Purpose_____________________________________________________________ 1
    1. Purpose.—a. This manual is published for the information and guidance of ordnance maintenance personnel. It contains instructions for the inspection, maintenance, and repair of the following 75-mm guns and carriages, and special field artillery vehicles:
    (1) 75-mm guns and carriages.
    		Mounted on 75-mm
    Gun	Recoil mechanism	gun carriage
    M1897	M189TA3	M1897
    M1897A1	M1897A6	M1897A2
    M1897A2		M1897MI
    M1897A3		M1897MIA2
    M1897A4	•	M1897A4
    M1897A2	M1897A5	M2A1
    M1897A4		M2A2
    M1897A2	M1897A7	M2A3
    M1897A4
    M1897A2	M2	M2A1
    M1897A4		M2A2
    		M2A3
    ♦This manual supersedes TM 9-1305, October 27, 1941, and TR 1410-126, July 31, 1925, including changes No. 1, January 3, 1927, and changes No. 2, January 2, 1934.
    449370°— 42— 1	1
    ORDNANCE DEPARTMENT
    TM 9-1305
    (2) Special field artillery vehicles.
    75-mm gun caisson M1918.
    75-mm gun caisson limber M1918.
    75-mm gun carriage limber M1918.
    Battery reel M1917A1.
    Artillery reel M1909ML
    Artillery cart M1918A1.
    b. These instructions are supplementary to those in the Field and Technical Manuals prepared for the using arm. Additional descriptive matter and illustrations are included to aid in providing a complete working knowledge of the materiel.
    Section II
    DATA
    Paragraph
    General___________________________________________________________________ 2:
    Artillery gun	book	(O. O. Form 5825)_______________________________________ 3
    Average life	of	gun__________________________________________________   4':
    Reference_________________________________________________________________ 5.
    2.	General.—Inspection is for the purpose of determining by critical examination the condition of the materiel, whether repairs or adjustments are required, that all modifications authorized by field service modification work orders (FSMWO) have been made, and to insure that the materiel is in such serviceable condition that it will function properly.
    3.	Artillery gun book (O. O. Form 5825).—a. Complete instructions for the use of this book are contained in instructions therein.
    Note.—The gun book should accompany the gun at all times, and inspectors should insist on seeing it. They should make sure that instructions therein are being carried out and that it is posted up to date.
    b. In the event the gun book should become lost and the original star-gage report of the gun cannot be obtained, the inspector may assume that the lands of the gun, 87.375 inches from the muzzle, are within the manufacturing limit of plus 0.004 on the normal dimension of 2,950 inches. If a star-gage reading of 2.964 is obtained (an increase of 0.010 over the maximum size of 2.954 for a. new gun), the remaining life of the gun may be appraised between 5.000 to 6.000 rounds.
    4.	Average life of gun.—The average life of the gun is approximately 10,000 rounds. The guns in service should be star-gaged after approximately 10 percent and 90 percent of their estimated accuracy life, and thereafter at each 10 percent during the remainder of their service.
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    GUN AND CARRIAGE, 75-MM, Ml 897	5-6
    5.	Reference.—The inspection of the gun and carriage as outlined in section IV, chapter 2, TM 9-305, should be followed. Those regulations also outline the inspection of the sighting equipment.
    Section III
    DESCRIPTION
    Paragraph
    75-mm gun M1897______________________________________________ ____ 6
    75-mm guns M1897A3. MIS: 7A4. mid M1897A2________________ ________ 7
    Breech mechanism. ___ ____________ _________________ _____________ 8.
    Firing mechanism________ _________________________________________ 9
    Piston rod coupler __ ________________________________ ___________ 10
    75-mm gun carriages M1S97 and M1897MIA2_____ _________ _ _________ 11
    High speed adapter for 75-mm gun carriage M1897A4_________________ 12
    75-mm gun carriages M2A1 and M2A2________________________ ________ 13
    6.	75-mm gun M1897.—a. General.— (1) The gun (fig. 3) is of the built-up type, consisting of the tube, breech hoop, ..inner locking hoop, outer locking hoop, muzzle hoop, and jacket, the latter being a bronze casting in which the gun barrel is supported.
    (2)	The breech hoop is shrunk on the rear end of the tube and the inner locking ring is screwed on the tube directly in front of the breech hoop. The outer locking ring screws on the exterior of the inner locking ring and also screws on the forward end of the breech hoop, securely coupling the parts. The jacket covers approximately the middle third of the tube, its rear end screwed on the forward portion of the inner locking ring. It is secured in position at its rear end by four jacket locking screws. The muzzle hoop is screwed on the muzzle end of the tube and is secured in position with four muzzle hoop set screws.
    A Tube.—The tube, 11A (fig. 3), is a forging and extends from the muzzle to the rear end of the powder chamber. Pockets in the rear face form seats for the arms of the extractor.
    c.	Breech hoop.— (1) A portion of the breech hoop, 8A (fig. 3), extends to the rear of the tube to form the breech recess, the interior of which is threaded for the reception of the breechblock. In the forward face of the recess, pockets are formed to correspond with the contour of the arms of the extractor and form a clearance to permit the extractor to pivot on the extractor spindle, which passes through the hole in the left side of the hoop.
    (2)	Between the two projections on the left side of the breech hoop (fig. 5), the breechblock stop swings on the block stop hinge screw and is locked in position by the breechblock stop pin. The projecting lug at the lower right on the breech face forms a stop
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    against which the breechblock arm strikes when rotating the breechblock to the fully closed position. Just above the latter stop surface, the breechblock latch catch is inserted and secured by the three latch catch screws.
    (3)	The dovetailed seat at the top center line of the rear face of the breech hoop is for the rear sight. This rear sight is secured by the rear sight blind screws. Two leveling plates are located on the top center line near the breech end and form a surface in alinement with the bore for the application of the gunner’s quadrant.
    (4)	A recoil lug on the under side of the hoop contains a rectangular hole for the piston rod coupler key, by means of which the gun is attached to the piston rod coupler assembly. The hole which extends upward through the recoil lug into the breech recess is for the safety bolt. The recess in the front face of the recoil lug is for the piston rod cushion. The right and left cradle protection plates, 14L (fig. 3), are attached with seven screws each to the sides of the hoop. They form the continuation of a similar shape on the sides of the jacket for the purpose of protecting the slides and roller paths on the cradle from the entrance of foreign matter.
    d.	Jacket.— (1) The jacket envelops the middle portion of the tube. It has on its under side a box-]ike extension which supports the gun in the cradle. The lower faces of the right and left sides of this extension are inclined slightly, with relation to the center of gun, inclining farther from the center at the breech than at the muzzle end of the jacket. These lower faces are fitted with the front, intermediate and rear slides riveted to the jacket and these slides rest upon the inclined slide surfaces in the cradle, while the gun is in battery. In recoiling, the gun moves off the inclined surfaces onto the jacket rollers.
    (2)	Between the front and intermediate slides, a jacket roller (fig. 3) is housed in a jacket roller upper bearing, and intermediate roller lower bearing. Between the intermediate and the rear slides, a jacket roller, 19K (fig. 3, sec. C-D), is housed in a jacket roller upper bearing and rear roller lower bearing. These are retained in the jacket by the jacket roller bearing screws and the latter are secured with the jacket roller bearing screw locking screws.
    (3)	Two roller oiler nozzles are located in each side of the jacket above the rollers to facilitate oiling the upper and lower bearings. Each nozzle contains a valve and valve spring.
    (4)	The rectangular hole through the sides of the jacket receives the jacket crosspiece, the upper side of which bears against the upper
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    GUN AND CARRIAGE, 75-AIM, Ml 89 7	6
    roller paths when the gun is in battery. This prevents the gun from whipping upward in the cradle when it is fired.
    (5)	The T-slot in the muzzle end of jacket receives the sweeper plate guide assembly. The sweeper plate is held against the sweeper plate guide and the front end of the jacket. Both are secured in position by the sweeper bolt and its pin.
    (6)	The dovetailed slot in the top at the rear end of the jacket receives the front sight which is secured in position by the front sight pin.
    e.	Muzzle hoop.—On the bottom of the hoop a projecting lug extends from the right and left sides. A round hole in each at right angles to the bore of gun receives the two muzzle roller trunnions, which are secured on the inner side of the projections with the trunnion nuts. These are pinned in position permanently with the trunnion nut pins. Directly above the trunnions a rectangular hole passes through the hoop into each end of which a muzzle roller cover, 12A (fig. 3, sec. G-H), is inserted. Between the two covers a muzzle roller cover spring guide is placed with a roller cover spring on each end. The springs act to force the covers apart and the latter are retained in the hoop by a muzzle roller with its assembled bushing placed on the outer end of each trunnion. The rollers in turn are retained by a muzzle roller side plate placed on the end of each trunnion and secured with a muzzle roller center screw. The rectangular hole which passes through the hoop, being open on the under side between the two projecting lugs, is covered with the muzzle hoop bottom plate, secured with six muzzle hoop bottom plate screws, to hold the covers in position.
    /. Sweeper plate guide.—The guide is assembled into the T-slot in the under side of the muzzle end of the jacket and is formed to fit over the arched and flat surfaces of the cradle. It is provided with a sweeper plate guide felt lining secured to the guide with the six sweeper plate, guide lining rivets, the felt lining sweeping the surfaces during recoil and counterrecoil.
    g. Sweeper plate.— (1) The plate, 16A (fig. 3, sec. J-K), together with the sweeper plate guide, is secured to the muzzle end of the jacket with the sweeper bolt and its pin. The plate is for the purpose of excluding dust and dirt from the roller paths and inclined slide surfaces of the cradle, and at the same time distributes the lubricant by wiping the surfaces each time the gun recoils. It also helps to center the gun in the cradle.
    (2) The plate carries at each end a felt-pad holder, 15D (fig. 3), each secured to the sweeper plate with two felt-pad holder rivets. The
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    roller path felt-pads (right and left) are carried on the stem of the holders and compressed between the surfaces of the sweeper plate and the felt-pad plates. The latter are provided with four felt-pad plate points in each and these project into the pads at the four corners, tending to preserve their shape and position. The pads are held between the plates and secured in position by the felt-pad holder nuts.
    (3) The slide sweeper blocks. 15A (fig. 3, sec. J-K), assemble in the plate against the pressure of the slide sweeper block springs, and are retained by cotter pins. The outer ends or surfaces of the blocks sweep the inclined slide surfaces of the cradle.
    7. 75-mm guns M1897A3, M1897A4, and M1897A2.—a. The M1897A3 and M1897A4 guns are M1897 guns modified. This modification consists of removing a portion of the jacket forward of the front sight, all parts attached thereto including the rollers and sweeper plates. Four supports are then assembled over the tube and locked in position by tangential pins. To these supports are fitted steel rails on which are assembled bronze bearing strips.
    b. Except for the above mentioned modification, these guns are duplicates of the M1897 in all respects.
    c. The 75-mm gun M1897A2 is similar to the M1897A3 and M1897A4, and is now standard for future manufacture.
    8. Breech mechanism.—a. General.—The breech mechanism of the 75-mm gun Ml897. M1897A3, M1897A4, and M1897A2 (figs. 5 and 6), consists of the breechblock assembly, breechblock latch assembly, breechblock latch spring, firing hammer assembly, firing hammer pin, firing rack assembly, firing rack spring, firing rack spring assembling pin, operating handle plunger, operating handle plunger block, operating handle plunger screw, and safety piece assembly.
    b.	Breechblock.—The breechblock, D1789 (13C) (fig. 6), is cylindrical in shape with threads on its outer circumference. Two holes extend through the breechblock just above the center and are spaced 156° apart. The larger or loading hole is cut through to the exterior of the block on one side, making a U-shaped passage for the insertion of the ammunition into the chamber of the gun. The smaller hole receives the firing pin, B 8378 (24E), by means of which the primer is exploded. A small vent hole extends upward at an angle from the breech face of the block to the forward interior of the firing pin hole. This gives vent to any gases that may escape to the interior of the breechblock due to a punctured primer or from other causes.
    c.	Loading hole.—The forward portion of the loading hole is beveled on one side by forming upon it a helix of approximately 15° angle. This bevel acts on the base of the cartridge case, forcing it into the chamber of the gun.
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    GUN AND CARRIAGE, 75-MM, Ml 8 97	8
    d.	Circular groove.—The circular groove and circular incline in the muzzle face of the block form a clearance for the extractor, C3746 (27B) (fig. 5), and the extractor tang, B8381 (14C), the latter protruding from the rear of the extractor. At the termination of the circular groove the extractor cam is inserted, which actuates the extractor by striking the extractor tang near the end of the opening movement of the block, thus ejecting the cartridge case.
    e.	Oval recess.—An oval recess is located in the exterior near the front face of the breechblock. This opening is used to engage the safety bolt in locking the block in the open position to prevent its operation while the gun is uncoupled from the recoil mechanism.
    f.	Safety bolt assembly.—The safety bolt, 23L (fig. 7), is a device to prevent the gun from being fired when the piston rod coupler key 15B, is not in place. The safety bolt lug projecting from the muzzle side of the bolt, engages in the sloping groove of the coupler key and when the key is removed this action causes the head of the safety bolt to engage in a slot in the breechblock. The breech side of the bolt contains a leaf spring (the safety bolt spring is secured with the safety bolt spring screw), which locates the bolt in its two positions by means of notches in the bolt seat into which the spring engages. Before attempting to remove the coupler key, place the breechblock in the open position.
    g.	Extractor.—The extractor, C3746 (27B) (fig. 5), is a hollow shaft having on its exterior two vertical projecting arms which lie in the pockets in the face of the breech recess. Between the arms is a projection containing a channel to receive the extractor tang, B8381 (14C). The hole through the shaft portion receives the extractor spindle which passes through it from the left exterior of the breech hoop, the spindle forming the pivot on which the extractor moves. Near the extremity of the arms, tangent to the bore of the chamber, lips are formed which engage the rim of the cartridge case in extraction.
    h.	Extractor spindle.—The spindle. C3751 (27A) (fig. 5), is a cylindrical shaft on one end of which is a curved projecting arm at right angles. The end of the arm is formed to enter upward into a hole in the projection which houses the breechblock stop and a groove in the end of the arm engages with the stop when the latter is swung into place. This securely locks the extractor spindle in position.
    i.	Extractor tang.—The tang, B8381 (14C) (figs. 5 and 6), slides into the channel or groove in the extractor. An oval projection on the tang acts as a key and enters into an oval hole in the extractor.
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    ORDNANCE DEPARTMENT
    The extractor tang is retained in position by the extractor spindle passing through the parts from the exterior of the breech hoop. The tang is so formed that it projects to the rear and has a beveled surface on one side, which contacts with the extractor cam near the end of the opening movement of the breechblock. A semicircular notch is provided on the opposite side to facilitate the removal of the tang in case of difficult disassembly.
    j.	Breechblock arm.— (1) The breechblock arm, D1788 (18A) (fig. 5), is set into a depression in the breech face of the breechblock and is secured thereto by five breechblock arm tap rivets. An oval hole in the outer end of the arm receives the breechblock latch pawl catch, A25057 (24A) (fig. 6). A threaded hole at the lower end of the arm receives the operating handle, C3748 (25K) (fig. 6), which is secured against turning by a steel pin. In the breech face of the breechblock arm a threaded recess in line with the hole for the firing pin receives the safety piece, C3749 (26A), assembly.
    (2)	Between the two projecting lugs on the breech face of arm the firing hammer. C3747 (24B) (fig. 6), is pivoted on the firing hammer pin, A25064 (24H). The hollow projection adjacent receives the firing rack spring, A25081 (24G), and the firing rack. C3750 (24C), which are retained by the firing rack spring assembling pin. The eye on the exterior of the projection is for the lanyard to pass through. A recess in tire forward face of the arm receives the breechblock latch spring and breechblock latch, the latter containing the pawl spring and the pawl. These are retained in the recess by the breechblock latch pin passing through the arm and the breechblock latch.
    k.	Operating handle.—The handle, C3748 (25K) (fig. 6), is a hollow cylinder having a threaded end to screw into the outer end of the breechblock arm. It 'is secured therein by the handle pin. The opposite end is threaded to receive.the operating handle plug, A25066 (25N), which retains the plunger cushion. The plug is secured in position with the handle plug locking screw. The interior receives the operating handle plunger. B8379 (25C), and the opening in the side is for the insertion of the operating handle plunger block. B8371 (25A).
    I.	Operating handle plunger.—The plunger, B8379 (250) (fig. 6). has a sliding fitted inside the operating handle. The rectangular hole in the rear end is located in line with the opening in the operating handle and receives the operating handle plunger block when the latter is inserted through the opening in the handle. The hole in the rear end of the plunger receives the operating handle plunger
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    GUN AND CARRIAGE, 75-MM, Ml 8 97	8-9
    screw which passes through the plunger block, retaining the parts in the operating handle.	x
    m. Operating handle plunger block.- The block. B<8371 (25A) (fig. 6). is a flat piece having two projections, and is assembled into the operating handle plunger, as previously explained. It moves with the plunger as the latter slides forward and rearward in the handle. The projection on its outer side protruding to the rear of the breechblock latch pawl, B8376 (26H), engages the latter when the forward movement of the handle plunger occurs in the recoil of the gun. The projection on the forward side covers the forward end of the elongated opening in the handle.
    n. Breechblock latch spring.—The spring, A25079 (26G) (fig. 6), is flat, having two leaves formed in the shape of a V. It assembles in the breechblock arm to the rear of the breechblock latch and presses the latter into engagement with the breechblock latch catch in the breech face of the gun.
    o. Breechblock latch and pawl.—The breechblock latch, B8375 (26M) (fig. 6). pivots in the breechblock arm on the breechblock latch pin. It has a prbjection on its inner end toward the gun, which engages in the groove in the breechblock latch catch when the breech is closed. Its outer end projects forward of the projection on the operating handle plunger block. A hole and a slot in this same end receive the pawl spring and pawl, respectively. The pawl pivots on the pawl pin and is actuated by its spring when the handle plunger moves forward as the gun recoils. This causes the rear end of the paw] to engage against the latch pawl catch and holds the breechblock latch disengaged from the breechblock latch catch in the breech face of the gun.
    p. Breechblock latch pawl catch.—The catch. A25057 (24A) (fig. 6), is an oval section having a flattened portion at its middle against which the pawl engages. It is inserted into the outer end of the breechblock arm and secured by the latch pawl catch screw passing through the arm into the hole in the end of the catch.
    9.	Firing mechanism.—a. General.—This mechanism is of the percussion type and is assembled in the breechblock arm and breechblock.
    b.	Firing rack spring.—This is a helical coiled spring assembled in the hollow projection on the breech face of the breechblock arm. It is retained therein by the firing rack and by the firing rack spring-assembling pin. the latter passing through the parts. The spring. A25081 (24G) (fig. 6). when compressed by pulling on the lanyard, furnishes the necessary force to the firing hammer to explode the
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    ORDNANCE DEPARTMENT
    primer. The rack also assembles in the projection on the breechblock arm, one end of it passing through the firing rack spring. The outer end, which protrudes from the projection, is furnished with a rack having seven teeth which engage with the spur teeth of the firing hammer. Between the second and third teeth from the end a small screw (rack screw) is inserted in the space and a corresponding gap is made in a tooth of the firing hammer. This compels the correct assembly of hammer to the rack. A slot crossing the outer end of the hole through the rack engages the projecting keys on the firing rack spring assembling pin.
    c.	Firing rack spring assembling pin.—The pin, A25065 (24F) (fig. 6), passes through the hollow projection on the breechblock arm, the firing rack spring, and the firing rack. It has two projections or keys on its smaller end, and on the opposite end a head containing a slot for the purpose of assembly and disassembly. The projection or keys are opposite one another and pass through keyways in the extremity of the hole in the firing rack. When the pin is inserted and' turned 90°, it engages in depressions in the rack and holds the parts together.
    d.	Firing hammer.—The hammer, C3747 (24B) (figs. 5 and 6), is pivoted between the lugs of the breechblock arm on the firing hammer pin. On its pivot end a number of spur teeth are formed in the shape of a small gear, its teeth meshing into those of the firing rack. The outer end forms the hammer portion and has attached to it the firing hammer link.
    e.	Firing hammer link.—The link, A25062 (25D) (figs. 5 and 6), forms a swinging connection between the firing hammer and the lanyard. It is secured to the hammer by the firing hammer link pin passing through the parts.
    /. Lanyard.—This consists of approximately 25 inches of sevenstrand chord, one end of which is passed through a pear-shaped hardwood handle and tied in a knot. The other end is passed through the eye on the breechblock arm and then looped in the firing hammer link.
    g.	Firing hammer pin.—The pin, 24H (fig. 6). is cylindrical a., each end with a projecting key at about its middle portion. One end being larger than the other in diameter, it can be inserted only through the arm into the hammer in one direction. It forms the pivot on which the firing hammer swings.
    h.	Firing pin.—The firing pin. 24E (fig. 6). passes through the hole in the breechblock arm and breechblock and is retained in position by the safety piece. It has a slight longitudinal movement which
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    is limited by a shoulder near its breech end. This movement allows the conical point of the firing pin to protrude through the muzzle face of the breechblock sufficiently to strike the primer cap when the firing pin receives the impact of the firing hammer.,
    i.	Safety piece.— (1) The safety piece. 26A (figs. 5 and 6), screws into the threaded recess in the breechblock arm and can be located at the two different points by means of the safety piece plunger. These two points are marked “Safe” and “Fire” on the outer surfaces of the breechblock arm. (On guns of French manufacture, these two points are marked “Tir” and “Route.”) In either position, the plunger engages into a suitable depression or recess in the arm. The plunger is assembled in the safety piece together with .the plungei spring and is retained therein by the plunger knob and plunger knob pin. Opposite the plunger a projection is fitted which forms the firing hammer lock.
    (2	) On the breech face of the safety piece a circular incline is formed which acts on the firing hammer when the safety piece is turned and located at the “Safe” position. The hammer is then drawn away from contact with the firing pin. In addition, the hammer is locked against operation by the firing hammer lock, which enters into a hole in the side of the hammer by reason of the safety piece being turned to the point “Safe.” When located at the point “Fire.” the hammer is free to function in firing.
    10. Piston rod coupler.—a. The piston rod coupler, 14A (fig. 7), is a forging having two arms and a seat for the piston rod nut. The arms have rectangular slots which line up with the rectangular slot in the gun lug. The gun lug and coupler are connected by the coupler key which is inserted through the rectangular slots in the coupler and gun lug. On the side of the coupler is attached a plate reading “Open breech before withdrawing key.” On the recoil mechanism of French manufacture the plate reads as follows: “OUVRIR LA CULASSE AVANT DE RETIRER LA CLAVETTE.” Due to the mounting of the gun and of the angular movement of the piston rod with respect to the gun during recoil, it is necessary that its attachment to the gun permit a certain amount of play. This play is taken care of by the coupler.
    6. The rear face of the piston rod coupler key. 15B (fig. 7), has a sloping groove in which a lug on the safety bolt engages. The lower face of the coupler key has a spring to lock it when in position.
    11. 75-mm gun carriages M1897 and M1897MIA2.—a. Cradle.—(1) The cradle is a steel forging, the ends and lower diagonal sides of which are covered by plates. Trunnions project from
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    the sides about midway of the length and rest in the hollow trunnion bearings of the rocker. Extended lengthwise in the upper part of the cradle body are two channels, one on each side of the gun and opening toward it. The inner surfaces of the upper and lower sides of each channel provide a path for the rollers or bronze bearing strips of the gun.
    (2)	In addition to the lower roller paths on the cradle there are two slightly inclined planes which slope downward to the rear upon which the gun rests when in battery. Bearings for the elevating yoke of the elevating mechanisms are attached by screws to the lower side toward the rear of the cradle body.
    (3)	Two circular openings, with a connecting hole between the two near the rear end, run lengthwise in the body of the cradle. The smaller opening, which is the recoil cylinder, houses the recoil mechanism and the larger, called the recuperator cylinder, houses the recuperator or counterrecoil mechanism.
    (4)	The front end of the recoil cylinder is closed by means of the respirator assembly. The rear end is closed by means of the recoil stuffing box head through which the recoil piston rod slides.
    (5)	The forward end of the recuperator cylinder is closed by means of the recuperator cylinder front head. The rear end is closed by means of the oil index assembly and the recuperator cylinder rear head assembly.
    1). Shield.— (1) (a) The 4-piece shield of American manufacture is for use on the 75-mm gun carriage M1897MIA2, and consists primarily of a right shield, a left shield, a right apron, and a left apron. An additional shield is provided for the protection of the sight.
    (5) The 4-piece shield of French manufacture is used with the 75-mm gun carriage M1897MfA2 (French). It is identical with the 4-piece shield of American manufacture, except that it is thinner. Shims are riveted to the shield at the points where the brake worm support and the left shield bracket come in contact with the shield. These shims increase the thickness of the shield to that of the American 4-piece shield at these points. This shield can be used on the 75-mm gun carriage M1897 (French), using additional shims, if necessary.
    (2)	The right and left shields are stiffened across the top and bottom by shield angles which are riveted thereto. Reinforcing strips are riveted to the edges of the opening in the shields which are made for the gun. cradle, and trail. Projections on the edges of the openings are reinforced and fit in sockets provided in the trail side plates for supporting the shield.
    (3)	The aprons, right and left, are hinged to the lower edges of the right and left shields. When in action, they hang down, protect
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    GUN AND CARRIAGE, 75-MM, Ml 8 97	11
    ing the space below the axle. For traveling they are swung up against the front face of the shields, slots in their faces engaging with apron latch staples riveted to the front face of the shields. They are secured in traveling position by keys through the staples, retained in place by leather thongs. The apron latch keys are attached to the shields by chains. The apron hinges are different in design from those used on the 7-piece shield; they are not interchangeable.
    (4)	Sight case hooks for supporting the sight and quadrant cases are riveted to the rear face of the right shield; two eyes, at the top of the case, hook over the two upper hooks, and a spring-controlled hook at the bottom of the case snaps over the sight case lower hook. A strap also passes through holes in the shield and secures the sight and quadrant case in place.
    (5)	Brackets for the sight extension case are riveted to the rear face of the left shield. The lower sight extension bracket forms a pocket for the lower end of the case; the two upper sight extension brackets form ears which support the case on each side. A strap around the upper sight extension brackets secures the case in place.
    (6)	The spare parts pouch carrier, consisting of an upper and a lower bracket, is riveted to the front of the left shield.
    (7)	The tool roll carrier, consisting of a built-up frame, is riveted to the front of the right shield.
    (8)	The 7-piece shield of French manufacture is for use on the 75-mm gun carriage M1897 (French), and consists of a right and left shield, a connecting shield, a right and left extension shield, and a right and left apron keyed and bolted together. An additional shield is provided for the protection of the sight.
    (a)	The connecting shield is riveted to the right and keyed to the left shield. The extension shields are bolted to the lower ends of the shields, right and left. The aprons are hinged to the lower ends of the extension shields. The apron hinges are different in design from those used on the 4-piece shields. They are not interchangeable.
    (6)	The sight shield, 48B (fig. 2). is attached by screws and nuts to a bracket on the left side of the rocker, forward of the main shield. An eyebolt in the sight shield carries a chain which secures the sight bracket cover.
    (c)	The method of attaching the shield to the carriage is the same as that used for the 4-piece shields.
    () With the traversing nut, 56F (fig. 8), in place, the portion of the axle to the left of the traversing nut is covered with the axle sleeve, 42C, the outside diameter of which is the same as that of the thread on the axle. Thus, bearing surfaces of the same diameter, right and left, are provided for supporting the trail. The axle sleeve, 42C, has a key riveted to its interior which fits a corresponding keyway in the axle, preventing rotation.
    (3) Rocker assembly.—(«) The rocker assembly of the M1897, M1897MIA2, and M1897A4 carriages makes it possible to change settings in elevation without disturbing the angle of site setting. It is the intermediate part between the trail and the cradle and is composed essentially of two rocker arms and the rocker segment.
    (&) The rocker arms, right and left, terminate at the front in hollow half trunnions resting in corresponding trunnion bearings in the trail side plates.
    () The inner ends of the spokes seat in the hub; the outer ends in openings cut in the fellies.
    (c) The tire is held in position on the fellies by shrinkage and by means of seven tire bolts.
    (<7) No lubrication opening is provided in this type of wheel; it is necessary to remove the wheel to lubricate the axle.
    12. High speed adapter for 75-mm gun carriage M1897A4.— a. There are two designs of high speed adapters. The first 496 carriages modified to take these adapters were designated as M1897MIE7. Later their designation was changed to M1897A4.
    20
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 89 7	12
    (1)	The left- and right-hand brake and axle brackets, group assemblies (fig. 24) bear on the axle of the carriage. The radius rods, group assemblies (fig. 11), one on each side of the trail, are attached at their ends to the radius rod ball studs assembled to the spindle brackets (fig. 11), and to the ball ends of the compensator shaft, restraining the brackets that bear on the carriage axle.
    (2)	To the machined face of the spindle bracket (fig. 24), there is attached by means of six cap screws, the housing plate assembly, consisting of the internal brake mechanism.
    (3)	The wheel spindle, C45203 (fig. 24). is pressed into the tapered hole in the spindle bracket, and the inner wheel spindle washer. A130413, slotted nut, BBHX2B, and cotter pin are attached to secure it.
    (4)	The brake drum inner packing, A130452 (fig. 24), is composed of a steel sleeve, two steel washers, and a ring of hard felt. This assembly is placed over the wheel spindle with the hard felt portion inserted into the recess of the brake drum. C62525. The purpose of this packing is to provide a seal for the grease within the hub and to keep all grease from the braking surface of the brake drum.
    (5)	The hub, C62505 (fig. 24), is a malleable iron casting. The inner flange is machined on its outer face for the brake drum, C62525, which is attached by eight screws, BCBX1DD, nuts, BBBX1I), and lock washers. BECX1L. The outer flange is also machined, and the outer rim is drilled for six wheel studs to which is assembled the disk and rim wheel on which the tire, 7.50 by 24, is mounted. The disk and rim wheel is secured by six conical-shaped nuts. The bore of the hub is recessed at its inner and outer ends for the taper roller bearings.
    (6)	The brake drum, C62525 (fig. 24), is a casting machined on its inner face to provide a bearing surface for the brake shoes.
    (7)	The hub cap, B144454 (fig. 24), is a pressed steel plate that is dome shaped. The hub cap and hub cap gasket, B144356, are secured to the outer flange of the hub by three round head machine screws and lock washers. The hub cap protects the outer roller bearing from grit, and acts as a seal for the grease within the cavity of the hub. It also provides an opening to allow adjustment for end play of the wheel.
    c.	(1) The radius rod group is composed of the radius rod, which is hollow, threaded internally at each end for a short distance to provide seats for the inner and outer radius rod compression spring plugs. Openings are milled on opposite sides of the rod a short distance from each end.
    21
    TM 9-1305
    12
    ORDNANCE DEPARTMENT
    (2)	The radius rod forms a housing for the ball seats, the ball seat compression springs, the ball seat compression spring plugs, inner, the ball seat compression spring plugs, outer. Two straight button head grease fittings are screwed through the rod and into the reservoirs.
    (3)	The ball seat compression spring plug, outer, is cylindrical in shape and threaded externally. Its faces are flat and the rear face has a slot milled in it for a screw driver.
    (4)	The ball seat compression spring plug, inner, is cylindrical in shape with both ends chamfered. The faces of the plug are flat.
    (5)	The ball seats are so shaped that they fit the radius rod ball studs and the ball ends of the compensator shaft.
    (6)	The ball seat compression spring, of i/^-inch square steel, is helical in shape. The outside diameter of the spring is approximately iy2 inches and the inside diameter % inch.
    (7)	The reservoirs are cylindrical in shape and hollowed out to retain the lubricating grease. They are drilled and tapped to receive the grease fittings.
    d.	The left- and right-hand compensator shaft support brackets are castings bushed with compensator shaft support bracket bushings and drilled and tapped to receive straight button head .grease fittings.
    e.	The compensator shaft, C45099 (fig. 11), is 1.76 inches in diameter and 45 inches long. Ball-shaped knobs are machined at each end. The shaft is drilled at the center and counterbored for the compensator ball stud.
    f.	The wishbone, C45202 (fig. 11). is of angle iron, bent into an irregular U-shaped piece. The ball socket bracket is riveted at the bottom of the U. Riveted to the left and right ends of the U are the left and right brackets which fit into the grooves of the axle collars. They are clamped into position by means of the axle clips.
    g.	(1) The left-hand brake level1 assembly is composed of the brake lever, to which are riveted the bracket and guide. The head of the brake lever is bushed with the brake lever bushing. The head of the lever is also drilled and tapped for a straight button head male grease fitting.
    (2)	The right-hand brake lever assembly is composed of the lever, to which is riveted the guide. The head of the brake lever is bushed with a long steel tube. On the opposite end of the tube is assembled the brake connecting lever. The tube is bushed at each end with the brake lever bushing. The head of the brake lever is drilled and tapped for a straight button head male grease fitting.
    h.	The wheel assembly is composed of the disk and rim wheel to which is assembled the 7.50 by 24 balloon tire group assembly. The
    22
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	12-13
    balloon tire, group assembly is composed of a puncture proof inner tube and a 7.50 by 24 8-ply casing. The balloon tire group assembly is retained on the disk and rim wheel assembly by the locking ring.
    i.	In all other respects the 75-mm gun carriage is the same as the 75-mm gun carriage M1897 or M1897MIA2.
    13. 75-mm gun carriages M2A1 and M2A2.—The carriage is of the split trail type. A trail lock is provided to lock the two trails together for travel. When the trails are in the closed position the ball portion of the drawbar end bearing. B144201 (fig. 15). welded to the right trail, seats into the socket portion of the drawbar end bearing bracket, B144200, welded to the left trail. The trails are locked together by a toggle type clamp actuated by the trail connection hook handle. C62484.
    a.	Recoil mechanism holding cradle.—The cradle trunnions (fig. 18) are assembled with trunnion bushings. Bl44265. which rotate on self-alining type bearings, consisting of trunnion balls, A156944. and caps, B107013 (fig. 17). The latter are alined in the top carriage by a projection seating in mating grooves in the trunnion bearings of the top carriage. 1 he assembly is locked to the cradle trunnions by the cradle trunnion nut. A143912. locked by screw, A167444. trunnion ball spacer, A156943. against trunnion bushing, B144265. and is secured to the trunnion bearing of the lop carriage by the trunnion ball outer and inner retainers. B144268 and B143600, with the inner and outer trunnion bearing plates, B144266 and B144267. connected by screws, BCKX1FU.
    b.	Elevating mechanism.— (1) By means of the elevating mechanism, the recoil mechanism holding cradle, recoil mechanism and gun are elevated or depressed to the various firing angles from 10° (178 mils) depression to 45° (800 mils) elevation. The elevating arc. 1)6658 (fig. 17), a segment gear of 42-20° involute teeth, is an integral part of the recoil mechanism holding cradle assembly. This elevating arc is actuated by the elevating pinion. B142227 (fig. 20). mounted on roller bearings housed in the elevating gear case, the latter being welded within the frame of the top carriage. On the right of the elevating pinion, B142227, is fixed the elevating worm wheel, B141439. It meshes with the elevating worm that is actuated by the elevating handwheel through the medium of the elevating handwheel gear assembly', B107062, and elevating shaft gear, B107043, which are mounted on ball bearings.
    (2) The elevating handwheel gear case, C58657 (fig. 20), is bolted to the outer right side of the top carriage. A straight button head fitting. CLDX1A, is assembled in the side of the case for lubricating purposes.
    23
    TM 9-1305
    13	ORDNANCE DEPARTMENT
    c.	Traversing mechanism.— (1) Traverse is accomplished by turning the top carriage about its pivot, the pintle pin. Movement of the traversing handwheel supported by the traversing handwheel shaft bracket is transmitted by the flexible joint, A138006 (fig. 22). to the traversing worm, B109247. which drives the traversing worm wheel, B109248 (fig. 21). The traversing worm wheel is assembled on the traversing pinion. B109246, and meshes with the teeth of the traversing rack. C59949, bolted to the axle. The traversing rack is stationary and the traversing mechanism is assembled to and moves with the top carriage.
    (2)	Rotating members of the traversing mechanism are mounted on antifriction bearings. Lubrication of the traversing handwheel shaft bearing and the traversing worm is through button head fittings, CLDX1A, assembled in the traversing handwheel shaft bracket and the traversing gear case.
    (3)	Control of maximum traverse is by means of stops, A141605 (fig. 22), one on each end of the traversing rack. C59949 (fig. 21). Assembled to the traversing gear case is a mechanism that controls the 45° traverse of the gun. By turning the spring plunger knob, A141655 (fig. 21), to lower the spring plunger, A141592, it engages with a stop welded to the axle bracket.
    (4)	Bolted to the left side of the top carriage is the traveling lock mechanism which is provided to secure the top carriage to the axle when traveling. This is accomplished by lifting up on the lock knob assembly, releasing it from its latched position, and swinging the traveling lock shaft to the rear. Maneuver the traversing handwheel until the traveling lock shaft can engage the traveling lock socket, which is bolted to the traversing rack.
    d.	Equilibrators.— (1) Two spring type equilibrators (fig. 23) are provided to neutralize unbalanced weight and reduce the manual effort required to elevate the gun through the elevation mechanism.
    (2) Each unit is composed of an outer cylinder assembly, an inner cylinder assembly, and an equilibrator spring. A155906.
    (a) The outer cylinder assembly is composed of a cylinder, B143542 (fig. 23). and an end, B443540, which is welded to the cylinder. The rod, A155908, passes through the end, B143541, is screwed into the end. B143540. and secured with a straight steel pin.
    (&) The inner cylinder assembly is composed of a cylinder, B143543, to which is welded an end, B143541.
    (c) The equilibrator spring. A155906, is placed inside of the inner spring cylinder assembly and the outer cylinder assembly slides over the inner cylinder assembly. The equilibrator trunnion pin, A441451.
    24
    TM 9-1305
    GUN AND CARRIAGE. 75-MM, Ml 897	13
    is screwed into the end. B143540, secured by lock A3552, and is used for adjustment as described in paragraph 18.
    e. Axle.—The axle is of welded steel construction and consists of an axle bracket assembly, axle bracket, left, assembly, axle bracket, right, assembly and axle tube assembly, welded into one complete unit. The disk and rim wheel spindles, C62266 (fig. 25), are assembled and secured by slotted nuts, washers, and a split cotter pin, to the axle brackets, left and right. They transmit the weight of the top carriage, gun and recoil mechanism to the disk and rim wheels and the firing jack.
    /. Brahe mechanism—(1) The brakes. C64675 (fig. 25), are of the internal expanding type. The brake shoes are' actuated by hand brake levers. C64752, which are connected to the brake cam shaft. B150693.
    (2) The movement of the brake levers (fig. 25) is controlled by the brake rack catch, engaging teeth in the brake ratchet rack, B150685.
    (3) The brake shoe (fig. 26) is a flanged segment, the outside diameter of which is covered with a brake lining and secured by ten tubular brass rivets. The brake consists of an assembly made of the brake shoes secured to the brake housing plate, assembly, C62668, by brake cam roller pins. B144962, and connected with the brake shoe adjusting wedge. B144959, by brake shoe links, B144960. The brake cam rollers, B144955, are held in contact with the brake cam, B144968, and the links are held in contact with the wedge by means of the three retracting springs.
    g. Brakes.—(1) When engaging the brakes, the movement of the hand brake lever, C64752 (fig. 25), through the linkage rotates the brake cam, B144968, causing the brake cam rollers, B144955 (fig. 26), to ride toward the high point of the brake cam and thereby forcing the brake shoes against the brake drum which is secured to the hub of the disk and rim wheel.
    (2) When the brake lever is released the tension of the retracting spring and the spring on the brake rod causes the brake cam to rotate to the released position. This action forces the brake cam rollers to the low point of the brake cam and thereby releases the pressure of the brake shoes against the brake drum.
    h. Disk and rim wheels.—The assembly consists of a commercial disk and rim, upon which is mounted a commercial 7.50 by 24 heavy duty truck and bus balloon tire. The inner tube of the tire is a commercial 7.50 by 24 puncture sealing tube equipped with a Schrader valve. The tire is secured to the disk and rim by a locking ring.
    25
    TM 9-1305
    14
    ORDNANCE DEPARTMENT
    Section IV INSPECTION OF GUNS, CARRIAGES. AND SPECIAL FIELD ARTILLERY VEHICLES
    Paragraph
    Inspection of M1897 gun mounted on 75-mm gun carriages M1897,
    M1897MIA2, and Ml 897A4________________________________________________ 14
    75-mm guns M1897A3, M1897A4, and M1897A2 mounted on 75-mm gun
    carriages M2A1, M2A2, and M2A3___________ _____________________________ 15
    inspection of gun carriages M1897, M1897MIA2, and M1897A4________________ 16
    Inspection of high speed adapter of the 75-mm gun carriage M1897A4_______ 17
    inspection of 75-mm gun carriages M2A1, M2A2, and M2A3___________________ 18
    Recoil mechanisms and their modifications________________________________ 19
    Inspection of recoil mechanisms__________________________________________ 20
    Checking distance from roller paths to inclined planes of cradle on car-
    riages M1897, M1897MIA2, and M1897A4___________________________________ 21
    Nitrogen pressure and floating piston friction of recoil mechanism mounted on 75-mm gun carriages M2A1, M2A2, and M2A3____________________________ 22
    Inspection of special field artillery vehicles___________________________ 23
    14. Inspection of Ml897 gun mounted on 75-mm gun carriages M1897, M1897MIA2, and M1897A4.—a. Accidents, and local defects of the bore, such as scratches, nicks, pitting, scoring, etc., cannot be passed on by any definite rule. The effect of all such defects is either to allow leakage of gas past the rotating band of the projectile and thereby promote further erosion of the forcing cone, or to wear away the rotating band so that the projectile does not attain its proper rotational velocity. Such defects should, therefore, be smoothed and rounded and, on the basis of their location, character, and extent, determination should be made as to whether they are apt to be injurious from the point of view of gas leakage and wear on rotating bands. Guns badly scored beyond the forcing cone should be reported to the Chief of Ordnance for final action,
    b.	The effect of pastilles upon the safety and accuracy of the gun is negligible so far as can be determined. It is realized, however, that definite facts are lacking and that the presence of pastilles is annoying to the battery personnel, and it has been decided to withdraw from service the guns having more than three pastilles the size of a 5-cent piece.
    c.	Deformation of the rifling at the origin in general consists of sheared lands and a flow of the metal in the grooves so that the pitch of the rifling for the first inch or two is considerably reduced. This is considered a serious defect and guns showing it to a marked degree will not be reissued.
    d.	The advance of the forcing cone is measured with the forcing cone gage or by means of a projectile. The normal distance from the
    26
    TM 9-1305
    GUN AND CARRIAGE, 7 5-MM, Ml 897	14
    edge of the chamber to the face of the projectile when shoved with the usual force of loading is 12 inches. When this distance (as checked by the use of several projectiles) has increased to 12.3 inches, or when the forcing cone gage shows the advance of the forcing cone 0.25 inch and the gun exhibits the usual amount of other defects, it should be withdrawn from service.
    e.	Experience has shown that the wear of a gun of small caliber, such as the <5-mm. is a factor of so many variables that condemnation on any single basis is unwise. The limits previously given should be used only as a general guide and a gun should be condemned only after careful consideration of each of the factors involved. It is evident that, a gun is still serviceable in spite of numerous bore defects if its dispersion is not great enough to endanger troops adv ancing under cover of a barrage or to cause waste of ammunition.
    /. Check the wear of the sweeper plate guide in the cradle ways. Insert a screw driver blade between the sweeper plate and the ciadle slide face and force the gun to one side. Draw a fine vertical pencil line over the face of the sweeper plate and the face of the cradle. Push the gun to the opposite side. The movement of the gun is indicated by the amount the line on the sweeper plate has separated from the line on the cradle front. Mark on the cradle the new position of the line of the sweeper plate, ff the distance between the two lines on the cradle is as much as 0.06 inch, put in a new sweeper plate guide assembly.
    g. Examine for missing sweeper bolt pin, condition of the threads of the sweeper bolt, worn or fouled condition of the roller path felt pads, worn slide sweeper blocks, broken spring, pins, etc.
    A. Examine for worn or fouled guide felt lining and condition of the threads of the jacket and guide for the sweeper bolt. These threads are frequently stripped by firing with the slide sweeper blocks incorrectly assembled so that they overhang the front of the cradle when the bolt is excessively loose in its seat. See that the jacket crosspiece is firmly secured and that it is modified in accordance with FSMWO C4-W15.
    i. The inclined intermediate slides of the gun and cradle are subjected to wear, especially if there is lost motion endways between the gun and piston rod, which allows a slight movement of the gun and cradle when traveling. Check the wear of the slides by means of the clearance, gage 10 (fig. 36), in the following manner: Remove the gun and thoroughly clean the rollers and the slides of the gun and the roller paths and slides of the cradle. Replace the gun and see that it is fully in battery. With the sweeper plate and sweeper plate
    27
    TM 9-1305
    14	ORDNANCE DEPARTMENT
    guide removed, force the gun over to one side. Insert the leaf of the clearance gage between the intermediate rollers and the lower roller path; it should go in easily. If it does not, or if the rollers are touching the cradle, it indicates that the cradle or the gun slides are worn and should go to a heavy shop for repairs. Look for flat spots on the rollers and see that the rollers revolve easily. Correct the rollers and refit (shim) the roller bearings, if necessary. Test the rear rollers and correct, if necessary, in the same manner as outlined for the intermediate rollers.
    (1)	In using the gage, pass it sideways between the intermediate roller and the side of the cradle. Turn the rod so as to place the thickness gage flat on the roller path. When the index mark on the handle of the gage is flush with the front edge of the cradle, it indicates that the gage is under the roller.
    (2)	Examine the muzzle rollers to see that they turn freely and have no flat spots. See that the spring covers are not damaged and that they function properly.
    (3)	Normally there is a clearance of 0.02 inch (manufacturing limit) between the gun rollers and the roller paths on the cradle when the gun is fully in battery. If the inclined planes show a wear of 0.01 inch and the blade of the clearance gage is 0.004 inch thick, it is readily seen there remains but 0.006 inch for wear of the gun slides. Therefore, it is important to determine the amount of wear of the inclined slides of the cradle when using the clearance gage in order to obtain a maximum wear of 0.016 inch of gun slides. Jacket rollers that are loose in the bearings will reduce the desired clearance between the rollers and the roller paths. Roller bearings must be corrected if looseness exceeds 0.002 inch. If the looseness of roller bearing should exceed 0.01 inch, the gun should be returned to an arsenal for repair.
    j.	The rear end of the piston rod will be found to have a flat cone point, which protrudes into a recess in the gun breech hoop apron in which piston rod pellets' (disks of leather) are fitted. These pellets, between the rod and recoil lug. take up all looseness in the coupler and key. The point prevents the loss of the pellets which should not be allowed to become too hard.
    Note. It is important that all looseness between the gun and piston rod be taken up to prolong the life of the gun slides, the cradle inclined paths, and the surfaces at the front end of the cradle. These surfaces which are in contact with the guide sweeper blocks and sweeper guide wear rapidly during road travel of carriages if there is any looseness present.
    k.	Examine the breech end for scores and bruises in the threads of the breech recess and at the edge of the chamber, wear of the rear
    28
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	14
    sight by the pawl, loose or worn latch catch, and operation of the hinged breechblock stop.
    1.	Breech mechanism.— (1) Breechblock and breechblock arm assembly.—Examine for scored or bruised threads on exterior of breechblock, worn, roughened, or loose extractor cam. bruised threads in the breechblock arm and deformed threads of the safety piece. Check fit of safety piece in breeckblock arm to see that it is not loose or unserviceable and that it does not allow the hammer to strike the firing pin. See that the gas vent hole is not clogged and that no looseness exists in the breeckblock arm and the operating handle, and that the latch pawl catch is not worn or loose. Examine the firing pin and see that it is not deformed or bent.
    (2)	Breechblock stop pin assembly.—Examine for bent or missing pins or breechblock stop pin head.
    (3)	Safety bolt assembly.—Examine for deformed upper end of bolt. 1 ug sheared off. or broken spring. Test the safety bolt by attempting to push it down after the piston rod coupler key is removed. If it can be pushed out of the way by ordinary pressure of the hand, the cause of the defective action must be ascertained and corrected.
    (4)	Extractor tang.—Examine for deformation or breakage.
    (5)	Extractor spindle.—Examine for bending or scoring.
    (6)	Extractor.—Examine for binding or breakage.
    (7)	Safety piece assembly.—Examine for bruised threads and deformed hammer stop screw.
    (8)	Firing pin.—Examine for deformed point or rear end.
    (9)	Firing hammer assembly.—Examine for condition of gear teeth or deformed hammer.
    (10)	Firing rack spring assembling pin.—Examine for deformed projections.
    (11)	Firing rack assembly.—Examine for condition of rack teeth and rack dowel screw.
    (12)	Firing rack spring.—Examine for weakness or breakage.
    (13)	Breechblock latch pin.—Examine for bending or breakage.
    (14~	) Breechblock latch assembly.—Examine for wear or breaks, worn breechblock latch pawls, weakened or broken pawl spring.
    (15)	Breechblock latch spring.—Examine for weakness or breakage.
    (16)	Operating handle plunger screw.—Examine for condition of threads.
    (17)	Operating handle plunger block.—Examine for worn or broken projections.
    (18)	Operating handle plunger.—Examine for condition of threads and scores on exterior.
    29
    li
    TM 9-1305
    15-16
    ORDNANCE DEPARTMENT
    15. 75-mm guns M1897A3, M1897A4, and M1897A2. mounted on 75-mm gun carriages M2A1, M2A2, and M2A3.— a. Examine the position-of the supports encircling the gun tube and note if they have moved from their original position. If supports have moved, a report should be submitted to the Chief of Ordnance. Examine the bearing strips (fig. 4) for rough or scored surfaces. Inspect for clearance between the front support and the bottom of the ways of the recoil mechanism. If the clearance found is less than 0.056 inch modify in accordance with FSMWO C12-W3.
    Z>. Examine the breech mechanism as outlined in paragraph 14Z (1) to (18), inclusive.
    16. Inspection of gun carriages M1897, M1897M1A2, and M1897A4.—a. General.—Try the smoothness of action in the trunnions in the following manner:
    (1)	Swing back to the trunnion caps, take off the rocker arm caps, and note whether the trunnions and caps are dirty, rusted, or show evidence of friction. Clean and lubricate the surfaces and then replace the caps.
    (2)	Remove the elevating screw pin and range rack screw. See that the cradle rocks freely in the zone of travel and that when the breech is raised, the rocker, although disengaged from the elevating pinion, is not drawn up with it.
    (3)	With the elevating screw pin and the range rack screw replaced, bring the range scale to 5,500. Run the rocker off the angle of site pinion and tilt the whole mechanism—rocker, cradle, and gun—without turning the elevating screw.
    (4)	When the parts are well kept, the breech preponderance should be such that the breech will move downward if the gun is approximately horizontal.
    b. Maneuvering mechanism.—Examine the traversing and angle of site mechanism to see that they are not damaged and that they function as they should. Measure the lost motion of the traversing handwheel—it must not exceed one-sixth of a turn. Measure the space between the elevating nut collar and yoke—it must not exceed 0.04 inch. See that the yoke oscillates freely and is not excessively loose in trunnion bearings. See that the angle of site worm gear shaft housing is not loose in the trail. Examine the rammer staff and sponge staff, make sure that they can be removed, replaced, put together easily, and that they are securely held by the chain.
    (1)* Examine for loose pinions on the elevating crankshaft and range scale shaft.
    30
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	16-18
    (2)	Examine for excessive wear as evidenced by end play and looseness of pinions on either of traversing or angle of site handwheel shafts.
    (3)	Examine for bent or loose handwheels, loose keys, and spherical covers.
    (4)	Examine for proper functioning of the angle of site handwheel latch and note if the latch enters the holes in the rim of handwheel.
    (5)	Examine axle spindles of the 75-mm gun carriages M1897 and M1897MIA2, for wear, scoring, and improper lubrication.
    (6)	Look over the shields to see that they are firmly secured, that the keys are equipped with thongs, and that the hinges of the aprons are in serviceable condition. Examine the sight case to insure that it is not torn or ripped, that it is held firmly by the locking catch, and that it contains the articles intended to be there. The packing should be properly covered with leather. See that the sight shield does not strike the bracket. Try the sights in the sight bracket.
    (7)	Examine brake worm quadrant housing for looseness on axle bracket and loose locking screws.
    (8)	Examine wheels for loose steel tires, broken, cracked, or loose spokes and fellies, excessive dish, and longitudinal play on axle.
    17. Inspection of high speed adapter of 75-mm gun carriage M1897A4.—a. It is necessary periodically to disassemble the high speed adapter in order to make an inspection of parts that are subjected to wear by the accumulation of sand and dirt getting into movable parts. Disassembly and assembly are covered in TM 9-305. . b. Examine all springs to see that they have not lost their flexibility or taken a set.
    c. Examine all ball and sockets for wear.
    (I. Examine bushing in the compensator shaft brackets and see that they are receiving proper lubrication.
    e. Examine all the rods and shafts for bending and misalinement.
    18. Inspection of 75-mm gun carriages M2A1, M2A2, and M2A3.—a. The force required to revolve the elevating handwheels should not exceed 10 pounds and the force required to revolve the traversing handwheels should not exceed 8 pounds. These forces will exceed the limits if bearings, bushings, gears, or worms are binding or insufficiently lubricated. The elevating handwheel might require excessive force due to improper adjustment of the equilibrators.
    b.	Examine all welds of the recoil mechanism and holding cradle for broken or cracked welds.
    c.	Examine the elevating arc for burred or deformed teeth.
    31
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    ORDNANCE DEPARTMENT
    d.	lest the elevating and traversing mechanism for backlash by turning the handwheels back and forth, noting the amount of play. If it exceeds one-quarter turn of the handwheel, make the proper adjustments.
    e.	Examine all fastenings welded to trails and top carriage for broken or cracked welds.
    f.	Examine the lifting jack of the M2A1 carriage, and note that there is no malfunction in the raising or lowering of jack.
    g.	Examine all traveling locks and see that they perform their function without binding or undue force in their maneuvering.
    h.	Examine the traversing rack and note whether the teeth are burred or deformed.
    i.	Elevate and depress the gun to test the action of the equilibrators. If the turning of the elevating handwheel requires more force than is prescribed in a above, make adjustment in the following manner: Depress the cradle until the equilibrator assembling nut. A137149 (fig. 23), carried as an accessory in the tool box, can be assembled at full length on the equilibrator spring rod. A155908, thereby retaining the equilibrator spring in compression. Elevate the gun until the equilibrator trunnion pin. A141451, is clear of its bearing. Release the trunnion pin lock and make the desired adjustment by screwing the equilibrator trunnion pin in or out. After making the adjustment, reengage the trunnion pin lock and lower the cradle until the equilibrator trunnion pin is seated in its bearing. Then remove the equilibrator assembly nut and place it in the tool box.
    j.	Examine the automobile balloon tires for wear of the treads.
    k.	Test the air pressure in the tires. The air pressure should be maintained at 30 pounds per square inch, regardless of the marking on the tires. Examine the side of the tire for broken wall.
    19. Recoil mechanisms and their modifications.—The following is a brief history of modifications that have been made to the M1897 and M1897MI recoil mechanisms. It is imperative, when making reports that the model designation of the recoil mechanism be given.
    a.	Recoil mechanism M 1.897.—This mechanism is the original “French” designed recoil mechanism and is designated as 75-mm gun recoil mechanism M1897.
    b.	Recoil mechanism M1897Al.—This mechanism is a modification of the 75-mm gun recoil mechanism M1897. This modification consisted of removing certain packing and substituting metallic packing.
    c.	Recoil mechanism M1897A2.—This mechanism is a modification of 75-mm gun recoil mechanism M1897. This modification consisted
    32
    TM 9-1305
    GUN AND CARRIAGE. 75-MM, Ml 897	19-20
    of removing certain packings of the recoil piston, stuffing box and floating piston and substituting X6 type metal packing. (The decision to make the above change in packing was revoked.)
    d.	Recoil mechanism M1897A3.—This mechanism is a modification of 75-mm gun recoil mechanism M1897. This modification consisted of eliminating the pump filling mechanism and some other parts of the mechanism.
    e.	Recoil mechanism, Al 1897Al^.—This mechanism is a modification of the 75-mm gun recoil mechanism M1897A1 and M1897MIA1. This modification consisted of eliminating the pump filling mechanism and some other parts of the mechanism.
    /. Recoil mechanism Al 1897A5.—This mechanism is a modification of the 75-mm gun recoil mechanisms M1897 and M1897MI. This modification consisted of substituting Duprene for certain packing, the elimination of trunnion connections for the oil pump M1A1, and the elimination of the elevating mechanism. This mechanism is to be used when mounting the 75-mm gun M1897A3 on 75-mm gun carriages M2A1 and M2A2.
    g.	Recoil mechanism M1897Ad.—This mechanism is a modification of the 75-mm gun recoil mechanism Ml 897 and M1897MI. This modification consisted of converting the mechanisnl to the 75-mm gun M1897A3, mounted on 75-mm gun carriage M1897A4.
    h.	Recoil mechanism M1897AU.—This mechanism is the original recoil mechanism of American manufacture.
    i.	Recoil mechanism A11897MIAl. This mechanism is a modification of the 75-mm gun recoil mechanism M1897MI. This modification consisted of removing certain packings and substituting metallic packings.
    7. Recoil mechanism Al1897ARIAft.—This mechanism is a modification of the 75-mm gun recoil mechanism M1897MI. This modification consisted of removing certain packing from the recoil piston, stuffing box and floating piston and substituting a new type packing known as X6. This modification was rescinded and the use of metallic packing abandoned.
    k. Recoil mechanism A11897MIA3.—This mechanism is a modification of the 75-mm gun recoil mechanisms M1897MI and M1897MIA1. This modification consisted of elimination of trunnion connections for the oil pump M1A1.
    20. Inspection of recoil mechanisms.—a. General.—(1) Inorder to make an intelligent and consistent inspection of the recoil mechanism, it is essential that the inspector be informed-not only as to its action, but also to certain technical peculiarities of the mechanism with which he will come in contact. The front and rear cylinder 449370°—42-----3	33
    TM 9-1305
    20	ORDNANCE DEPARTMENT
    packings, recoil piston and rear stuffing box, oil index, and filling valve, should be examined tor oil leaks. The recoil piston and rear stuffing box packings normally indicate a very slight leakage of oil, which insures lubrication. The leakage from the rear stuffing box is utilized to lubricate the elevating nut of the 75-mm gun carriage M1897, and modifications.
    (2)	The oil reserve or “reserve oil” are terms applied to that portion of the oil which normally separates the floating piston from the regulator. In the sectioned view (fig. 13) it is apparent that the compressed nitrogen will act to put pressure on the oil only as long as there is oil between the front, of the regulator and the floating piston. After these pieces come in contact, further movement of the floating piston is prevented and consequently the pressure of the oil may drop to zero. In amount, the reserve oil represents a volume corresponding to a movement of the floating piston of about one-half inch or exactly the same as the travel of the oil index between its extremes of movement.
    (3)	In determining the gas pressure, the operator is actually measuring the pressure on the oil transmitted to it by the compressed nitrogen through the medium of the floating piston. The gas pressure is originally established with the oil reserve in the recuperator and, therefore, it is necessary that a full reserve be present or its equivalent, if correct readings are to be obtained. The difference in pressure when full reserve is present and when there is barely sufficient reserve to indicate any pressure at all will be about 30 pounds per square inch.
    (4)	The friction of the floating piston to be considered is the sliding friction and not the standing friction. Therefore, the floating piston must be in motion when the reading is taken on the pressure gage.
    (5)	The oil in passing from the vicinity of the pressure gage to the vicinity of the floating piston, or vice versa, must pass through very small orifices. Because of the resistance offered in these orifices, if the recoil piston jack is operated rapidly in either direction, a misleading pressure will be generated in the vicinity of the gage and be registered thereon. For this reason the recoil piston jack screw must be operated at not over four turns per minute.
    (6)	Since the oil within the recuperator becomes sluggish at a low temperature its action through the small orifices is erratic, and the reliability of gas pressure measurements with the recoil mechanism at a low temperature is always doubtful. Therefore, if pressure must be tested in cold weather, it is necessary that the mechanism and extra oil be in a room warmed to at least 50° F. for 24 hours preceding the test.
    34
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	20
    (7)	Since the amount of nitrogen originally placed in the recuperator cannot increase, the pressure at any given temperature cannot become higher except by moving the floating piston forward so as to reduce the volume. This can occur if an excess of oil is introduced, as may be the case if the oil index is stuck and the sticking not noticed. Make sure the oil index is registering properly by draining the reserve oil and restoring some of it. The oil index will move in when the oil is drained and should move out as the reserve is reestablished. I ailure of the oil index is almost invariably on the outward movement.
    (8)	If nitrogen leaks past the floating piston it may be detected by sputtering and the foamy appearance of the reserve oil when draining out.
    b. Manometer test.— (1) When measuring the nitrogen pressure and friction of the counterrecoil mechanism, the gun must be in the horizontal position, disconnected from the piston rod, and the muzzle even with the front of the recoil mechanism.
    (2)	Remove the filling and drain plug located near the rear end of the right side of the cradle and insert the recoil pressure gage connection, C67579 (fig. 37). Before inserting, make sure that the valve release handle of the pressure gage connection is in the full open position. Secure the pressure gage, C6529, in the upright position by means of nut. A169748. In order to drain reserve oil from the cylinder, open the drain handle, A174168, and then screw in valve release handle. A174168. Oil will flow from the shaft of the drain handle and should be caught in a suitable receptacle until the flow practically ceases. The oil index should move in beyond the rear face of the cradle.
    Note.—If the oil index is binding and has not moved the full distance, it should be repaired.
    (3)	Place the thermometer in the reserve oil drained from the mechanism and make a record of the temperature. Keep the thermometer out of the sun. The thermometer should represent the temperature inside the recoil mechanism.
    (4)	The pressure gage connection described in (2) above, will be used for reading the pressure within the recoil cylinder. In this case the drain handle will be kept closed and the valve release handle turned all the way in so that the pressure will be transmitted to the pressure gage.
    (5)	To determine the nitrogen pressure of the mechanism and the friction of the floating piston—
    (a) Move the recoil piston to the rear by means of the recoil piston jack (fig. 37), inserted in place of the respirator, until a
    35
    TM 9-1305
    20	ORDNANCE DEPARTMENT
    pressure of approximately 100 kg. per sq. cm. (1420 psi) at 68° F. is registered on the pressure gage.
    Note.—1 kg. per sq. cm. s= 14.2 psi.
    (7?) Slowly turn the jackscrew (at a rate of 4 rpm) ten complete revolutions and while slowly making the tenth revolution read the pressure gage, tapping the gage lightly to overcome the effect of friction in the gage itself. This gage reading represents the gas pressure plus the friction of the floating piston (Ap + F). (Make a note of the gage reading.)
    () above_________ 133	kg.	per	sq.	cm.	(1,888 psi).
    Gage reading, () Low friction is caused by breakage of the flange of the silver ring bearings, cracking of Belleville springs or deterioration of the rubber, due to the action of sulphur in the ring. Any effort made to increase the friction by increasing pressure on the Belleville spring is likely to result in breaking the spring into small pieces, which would probably cause damage to the interior of the cylinder and piston rod.
    () Spin the wheel, moving the top of the tire forward; the jack-shaft and chains should move freely without dragging at the clutch.
    () Take out screw. A172171. holding filling and drain plug housing locking plate and take off the plate. A172141.
    (c) Remove the six screws of the right rear cradle side plate and pull off the plate.
    () If a new filling and drain plug housing is to be assembled, the Hat surface on the housing provided for the locking plate. A172141. will not be filed until the housing is screwed in place and the position of the flat marked, after which the housing will be removed for the purpose of cutting the flat.
    (c) Put the valve and its spring in place, triangular stem forward, after having cleaned all of the parts with greatest care. Place on the seat of the housing the leather housing gasket. A19767. which has been thoroughly cleaned and soaked for several hours in recoil oil. Screw the housing in tight. Put on the right rear cradle cover plate temporarily in order to mark on the housing the two flat sides required. Also mark the top part of the housing which will have to be cut to receive the housing locking plate. Back the housing out. cut the flats, and return the housing to place. Fill the reserve and retain the recoil mechanism for observation for 24 hours to ascertain that no leakage takes place. If at the end of that time there is no leakage, reassemble the right rear cover plate, the six cover plate screws, valve housing lock plate, and screw.
    (4)	To remove filling and drain valve housing.— (a) With the parts removed as indicated in (2) (a), (7>), and (c) above, remove the elevating screw oiling pipe, 2-97-22A (C57121), bv removing the screw, 2-97-44U (Al73736).
    (h) Remove the filling and drain valve housing support screw. A172194 (fig. 27). In removing this screw the gun will have to be dismounted, as the screw goes in through the top of the recoil mechanism.
    (c) Pull the filling and drain valve housing support off of the housing.
    (rZ) Remove the filling and drain valve housing screws, 2-97-44W (A172448), figure 27. fap the housing gently with the copper ham
    53
    TM 9-1305
    26	ORDNANCE DEPARTMENT
    mer until it loosens and then it can be completely removed by inserting a screw driver between it and the recoil mechanism and prying gently.
    d. Leakage around oil index.—(1) Tighten the oil index follower with the oil index follower wrench, A7488 (fig. 47). If the leakage does not stop, take out the follower and assemble new packing. Test the action of the index by draining and replenishing the reserve oil.
    (2) If any defects in the oil index cannot be corrected by the above methods, the recoil mechanism will have to be sent to an arsenal for repairs.
    e. Jerky action in returning to battery.—(1) Dirty or worn gun slides and rollers will cause this trouble. These parts should be corrected.
    (2)	Dirty oil or small particles interfering with valves, scored cylinders or piston rod. Return to an arsenal for repair.
    (3)	Recoil oil may contain air. This is due either to the escape of the nitrogen past the floating piston, or pumping air into the cylinder when refilling or replenishing with recoil oil. If air is introduced with the oil, the oil when drawn off, will contain large bubbles instead of the foamy appearance when nitrogen has escaped past the floating piston.
    (4)	If the presence of air in the recoil oil is due to the escape of nitrogen past the floating piston, the recoil mechanism must be returned to an arsenal for repair.
    (5)	When the presence of air in the recoil oil is due to the introduction of air with the oil when refilling or replenishing, proceed as follows: Drain off the reserve oil. Remove the air vent plug, A154552 (fig. 27), on top and near the rear of recoil cylinder. Raise the rear end of the recoil mechanism slightly and, using the oil pump, pump oil into the system, using slow and continuous strokes until the air bubbles cease to flow. Replace air vent plug. (If new air vent plug is required it will have to be made locally.)
    /. Retraction test.—A final test may be given the recoil mechanism as follows: With one end of a sufficiently strong cable passed through the gun bore and looped securely around a hardwood block at the muzzle and the other end secured to a 2-ton chain block or tractor, the gun may be carefully retracted a maximum of 45 inches. A piece of sound 2 by 4 timber, exactly 44 inches long, and placed between the gun breech lug and the rear end of the cradle so that it does not bear upon the oil index, will hold the gun in the retracted position. Be sure the timber is securely set against gun and cradle. Carefully detach the chain block or tractor from the cable and, standing well to one side of the gun, pull out the hardwood block at
    54
    TEXAS STATE COLLEGE FOR Wnur,.
    ■ g --- u 'UK WuMtN
    LIBRARY ™ 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	26-27
    the muzzle, draw the cable out of the gun through the breech, and close the breech. Allow no one to stand in front of the gun or to project an arm in front of it while the cable is disconnected. Elevate to maximum elevation and jerk out the rear end of the 2 by 4 timber with a piece of rope. Note that the gun returns smoothly and fully into battery without shock. It will require approximately 4,400 pounds pull to retract the gun.
    g. Repair of worn trunnions.— ^ When it is found that the oil grooves in the trunnion bearings of the rocker arms have worn ridges on the trunnions, the trouble should be corrected as follows:
    («) Remove the recoil mechanism and place it on a work bench or trestle bottom side up. With a flat file smooth off the ridges caused by the oil groove and finish with fine emery cloth. No effort-should be made to true up the trunnions, as they only have a movement of 29° and a true circle is not absolutely necessary for a repair job. When time is not a factor the recoil mechanism should be returned to an arsenal where the trunnions can be turned down and a split steel liner applied.
    (b) Replace the recoil mechanism in the rocker trunnion bearings. Before replacing the rocker arm caps, place on each trunnion, a piece of lead about y16 inch thick, y$ inch wide, and 1)4 inches long. Put on the rocker arm caps and force them all the way down with the trunnion bearing caps. Remove the rocker arm caps and measure the thickness of the leads with a micrometer. The thickness of the leads represent the amount to be planed off the edges of the rocker arm caps to bring them to a bearing on the trunnions. Remove this amount from the edges of the caps.
    (2) The space between the rocker arm caps and the trunnion caps should be filled in by welding or by brazing on sufficient metal to allow them to be bored to the correct diameter to form a bearing on the rocker arm caps. The boring should be done in a lathe.
    (3) It is advisable to use a file with two safe edges so that the shoulders of the trunnions will not be marred. Care must be taken to insure that no more than the required amount of metal is removed from the edges of the rocker arm caps. Remove only enough metal to give a proper bearing and to take up the lost motion without binding. It is advisable to make a tool steel key for forcing the trunnion caps down on the lead instead of using the regular trunnion cap keys.
    27. Recoil mechanism M2.-a. The recoil mechanism M2 combines the cradle and recoil and counterrecoil mechanisms. The cylinders which house the recoil and counterrecoil mechanism are
    55
    TM 9-1305
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    ORDNANCE DEPARTMENT
    attached to the cradle by screws and dowel pins as indicated in figure 16.
    b. The recoil and counterrecoil parts of the mechanism function in the same manner as described for the M1897 recoil mechanism.
    c. The manometer test should be made in the same manner as prescribed in paragraph 205, c. and d.
    28. Elevation mechanism and range scales of carriages M1897, M1897MIA2, and M1897A4,— a. (deneral.—The elevating mechanism controls the angular relation of the cradle and rocker. As the frame or yoke of the elevating mechanism is fitted and attached to the cradle, it is regarded as a part of the recoil mechanism.
    b.	Ta replace elevating yoke bearings.—After considerable use the elevating yoke bearings may become worn and require adjustment.
    (1)	Dismount the elevating yoke as outlined in c below.
    (2)	Replace bearings and reassemble.
    c.	To dismount elevating yoke.-—It will be found much more convenient to dismount the recoil mechanism and turn it upside down upon trestles or other suitable support.
    (1)	Remove the screws from the elevating yoke bearing, right, having previously marked the screws to insure their return to original holes.
    (2)	Likewise remove the screws from the elevating yoke bearing, left.
    (3)	The elevating yoke is then free from the cradle.
    (4)	Examine the bearings for excessive wear.
    d.	To dismount elevating crank.— (1) Remove the cotter pin from the elevating crank pin.
    (2)	Remove the crank pin, being careful not to lose the washer, spring, and cotter pin.
    (3)	The crank will then lift off.
    e.	To dismount elevating crankshaft.— (1) Dismount the elevating crank as described in d above.
    (2)	Using a screw driver behind each end of the crosspiece of the shaft, apply enough leverage to remove it. Be careful not to lose the elevating crankshaft washer.
    (3)	It is well to mark the position of the shaft on the elevating crank locking plate when the crank is vertical or in some noted position so that the pinion can be reassembled on its hexagon seat exactly as before.
    /. To dismount elevating crank locking plate.— (1) Drive out the elevating crank locking plate pin.
    56
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	28
    (2) lap gently on the rear of the plate with the copper hammer until it moves off.
    (3) Do not straighten the pin as the bend in it is to hold it in place.
    g.	To dismount elevating nut.—fJT) The elevating crank, shaft, and bevel pinion must be dismounted before the nut can be removed.
    (2)	Drive out the elevating nut collar taper pin.
    (3)	Unscrew the elevating nut collar.
    (4)	Lift out the elevating nut.
    h.	To remove range scale.— (1) With the gun horizontal, set the range scale at zero.
    (2) Lake off the elevating crank locking plate.
    (3) Take off the range scale shaft nut, 67 A (fig. 10), and slide the range scale assembly off the shaft. Note that it is the function of the range scale movable pinion spring, 67B. to push the movable pinion to slightly mismatch the teeth of the fixed pinion and thus take up any lost motion in the range rack.
    i.	To dismount range rack. range scale being dismounted.— (1) Set the range rack to about 2,000 meters.
    (2)	Remove the elevating screw pin and let the cradle down upon the rocker.
    (3)	Remove cotter pin from range rack screw and remove the screw.
    (4)	Raise the rear of the cradle and take hold of the rack to prevent its falling, lhe rack will slide downward and clear of the guides. Let the cradle rest on the rocker.
    (5)	When the hole for the range rack bushing and the range rack becomes worn sufficiently to warrant replacement, the oversize bushing, 2—97—71 A, will be used and the range rack reamed to fit.
    (6)	When it becomes necessary to replace the range scale shaft, the shaft, 62H (fig. 10), will be issued with a blank flange and will have to be marked and drilled at assembly, as the holes in the cradle for the retaining screws are not equally spaced.
    j.	To remove range rack and range scale—cradle and gun being as ,eft by preceding operation.—Lift the rear of the cradle, place the range rack between its guides, the lower end of the rack resting in its place on the rocker, and let the cradle down on the rocker.
    (2)	Assemble the elevating screw pin and set gun horizontally with the angle of site handwheel.
    (3)	Set the range rack at zero by means of the elevating crank and shaft assembled momentarily for this purpose.
    (4)	Turn the range scale so that the zero faces the index and slip the range scale assembly into place. Note that it is only when rack and scale are at zero that the four beveled teeth of the movable
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    TM 9-1305
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    ORDNANCE DEPARTMENT
    pinion are opposite the four upper teeth of the rack which are beveled to suit.
    (5)	Screw the range scale shaft nut on tightly, care being taken not to break it.
    (6)	Slide the rack up and down to make sure there is no stiffness-in the motion.
    (7)	Screw in the range rack screw and put in cotter pin.
    (8)	Assemble the elevating crank shaft and locking plate and pin.
    k.	To dismount range rack only.— (1) The range scale nut may be unscrewed and the range scale slid outward sufficiently far to disengage the pinions from the rack without dismounting the elevating crankshaft locking plate.
    (2) The scales on the range scale and range rack are supposed to come to zero when the bubble of the angle of site level (angle of site dial being at zero degrees) and of a master level placed on the leveling plates of the gun are centered. When the gun is in normal horizontal position, movement below zero is prevented by contact of the lug on the elevating yoke with a projection on the rocker. If, in changing either range scale or range rack, the zeros on range scale and range rack do not agree, the difference measured on the scale should not exceed 2 mm. If it does, try first another rack, then, if necessary, a new scale. If the range scale zero coincides fairly well with that of the range rack, but neither moves as far as the index, file the upper face of the lug on the elevating yoke, being careful to keep the lug straight and in contact over its whole surface. After any change in range scale or rack, test the sight bracket setting.
    7. Lost motion in elevating nut.—Note that firing stresses tend to force the elevating nut upward through the yoke. Looseness, therefore, probably represents wear of the contact surface of the elevating nut collar against the elevating yoke. Vertical play of the elevating nut often results in chattering in the beveled gearing. I he maximum end play allowable has been fixed at 0.04 inch. Note also that the stop on the elevating nut collar is located with reference to the start of thread on the elevating screw. With the stop in contact it is convenient to have the 5,500 graduations on the range scale and range rack fall opposite their indices. Obviously the stops must not be advanced so as to prevent the range scales coming to full elevation. A little further movement does no great harm. The principal object of the stop is to prevent the locking together of the elevating screw and elevating nut by forcing the nut against the shoulder. To eliminate the lost motion in the elevating nut, measure the existing end motion of the elevating nut and subtract this amount from the thick-
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    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	28-29
    ness (nominally 1 mm) of a washer, 2-97-69B. Take off the elevat-mg nui co!lar 68D (fig. 10), using the elamp wrench, 1 (elevating nut collar) (fig. 36), true up in the lathe chuck and face off from the upper edge the difference so found. Assemble the washer and collar and the elevating nut should turn freely in the yoke without any end play 1 l)t a new taper pin in the elevating nut collar, correcting the hole tor it, if necessary, with No. 2 taper reamer, 5 (fig. 36).
    ’M7a/7 new elevat™g ’>«< collar. 2-97,-70A .—Remove the collar, 68D (fig. 10), to be discarded and any adjusting washers which may have been added and screw on the new collar until the elevating nut rotates freely without play. Trace on the collar the shape of the radial stop. File that stop to shape. File flush, if necessary, the lower face of the collar. Place the elevating nut collar so prepared 111 the elevating nut collar jig, 9 (fig. 36). Ascertain whether the collar is well seated m the jig and the vertical face of its radial Stop IS m contact with the corresponding vertical face of the jio-. Fix the collar in this position by means of the clamp and tightening screw. Start the hole m the nut collar with the end milling cutter to avoid starting the drill on an oblique surface, then drill the hole with the. 4-mm twist drill. 3 (fig. 36). Mount the collar on the e evatmg nut and ream with the taper reamer, 5 (fio- 36) Qut recess in the collar for the head of the pin. Assemble the pin
    29. Trails M1897, M1897MIA2, and M1897A4.-«. Angle of site worm gear shaft housing loose.—Tighten and lock (center punch) tie screws, except three on the French carriage M1897, which are to be removed for the insertion of rivets having heads 20-mm diameter which function to oppose the shearing stress. The heads of these rivets go through the housing and enter by 1 mm in the side plate The American-built carriages M1897MIA2 have these rivets alreadv set. Figure 28 shows the rivet hole on the right side and the two on the left side of the French carriages M1897. which are to be fitted with the housing rivets, 2-94-60M. The square-faced counterbore which it may be necessary to improvise for enlarging the rivet holes’ in the housing and side plate of French carriages to 20-mm (25/ inch) diameter, should have a guide to center the counterbore with the old rivet hole. In setting the rivets lay the trail on the side. Do not brace the bucking-up bar against the opposite side plate. Set it against a block of wood. Set rivets hot after checking the location o the housing. The rocker rack must not come in contact with the rack guide of the housing.
    b.	Axle bracket bolts.— The axle bracket bolts may become loose or broken.
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    TM 9-1305
    29	ORDNANCE DEPARTMENT
    (1)	Loose bolts.—Remove cotter pin. tighten nut, and replace cotter pin. It may be required to file the face of the nut slightly to bring the slot in the nut around opposite the cotter pin hole in the bolt to permit assembly on the pin.
    (2)	Broken bolts.—Broken bolts must be removed and replaced. Neglecting to do so may result in the cracking of the axle brackets. To replace the lower bolts of the left axle bracket it is necessary to remove the rammer sheath nearest the left side plate: remove the two bolts securing the mouthpiece to the front plate and then withdraw the sheath and mouthpiece as a unit from the trail.
    c.	Left axle bracket cracked.—If the sum of the lengths of the cracks on each side of the trail of the traversing gear case is greater than 40-mm (1%6 inches) replace the bracket.
    d.	To dismount left axle bracket.—(1) Mark the bolts and their respective nuts in order that the cotter pin holes match as desired in remounting.
    (2)	Remove both shields and the brake worm quadrant shaft socket nut directly under the left axle bracket. Place a lifting jack in the center of the axle housing and raise the carriage high enough to get a trestle or blocking crosswise under the shield lower sockets. The trestle or blocking should be high enough to raise the wheels about 2 inches clear of the ground. Remove the left wheel and drop the brake mechanism. With a socket wrench remove the nuts, and with a screw driver under the front end pry off the angle of site worm gear housing. Take out the locking screw and take off the angle of site worm gear shaft nut. 2-94-60E, on right side of trail. Pull angle of site worm gear shaft out to the left, being careful not to let the angle of site worm gear pinion drop. Remove the axle bracket bolt nuts and draw the axle bracket to the left along the, axle. If it is desired to remove the axle bracket completely, remove the right wheel and right axle collar and withdraw the axle.
    (3)	Before replacement of the bracket, inspect, and if necessary, improve the fit of the gear cover, 2-94-56E (fig. 9). on the gear case and of the handwheel shaft, shaft brace and gear cover key assembly. Examine the traversing gear case half bushings for wear and for end play of the traversing intermediate gear and refit or replace the bushing to secure a running fit of the gear. Try the traversing nut for wear on the axle threads; if necessary, replace with a new traversing nut assembly (par. 31 d).
    e.	Axle housing rivets loose.—Put in new rivets. The heads must fit the countersink exactly. On the side plate form a half button head. 3 to 4 mm high (0.14 inch).
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    f.	Axle housing or axle bracket distorted and out of line._If dis-
    tortion is m the direction which tends to bring the trunnion beariuos closer together and persists after tightening all the bolts, the rails may be spread by a jack improvised from a 0.75-inch bolt cut to length, and a nut. Peening the axle housing on the side it is desired to lengthen may be necessary in extreme cases.
    g.	1 runnion caps loose.—The rocker arm caps (fig. 1) and trunnion caps must be kept in good condition, free from rust and scores. The rocker arm caps may be just loose enough to allow full and easy movement without play. Oversize trunnion cap keys, 2-94-73D. are issued for fitting in worn key slots. These keys are hardened and must be ground to fit. If trunnion cap pins are to be replaced, refer to FSMWO C4-W8.
    h.	Bent or broken tail handles.—Straighten or replace. New tubes with plugs may be pinned in the old handle brackets. Replace any loose or sheared rivets in handle bracket. Entire trail handle assemblies are included in the list of organization spare parts.
    «. Bloat damaged.—The float may be cracked or lunette seat stretched. Replace the damaged float with a new one fitted in place.
    j.	Float bushing worn.—Replace the float bushing, 2-94-22F. when the lunette is loose in the bore and when wear, evidenced by end play of lunette, is in excess of %2 inch. In replacing the new bushing, the chamfered end must be beaded over after assembly and its flange should contact solidly with float. (This applies to M1897MIA2 carriage only.)
    k.	Lunette bent, ring worn or broken, and threads worn.—Replace rhe lunette when the metal of the eye is reduced to 1 inch in thickness and threads are worn excessively as evidenced by end play of the nut on threads. To dismount the lunette take out the float protection plate pin, 2-94-22C. and remove the float protection plate assembly. Take out the lunette nut locking screw, 2-94-23M, and unscrew the lunette nut, 2r-94-23F, with the lunette nut wrench, 6 (fig. 39). In replacing a lunette be sure that the small table in the eye which contacts with the spur of the limber pintle hook, to hold up the pole, is underneath. If a spare nut only is to be assembled, the locking screw holes are drilled and tapped after the lunette nut has been set up. If. after reassembling the removed nut, the locking screw notches go beyond their former positions, the locking screw must be relocated. The lunette nut must be set up tight enough to prevent the lunette from moving. (This applies to M1897MIA2 carriage only.)
    I.	Spade distorted.—If the distortion is greater than 10-mm (about % inch), change the spade. The spare spade 2-94-73K. is issued
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    29-30	ORDNANCE DEPARTMENT
    without bolt holes and must be fitted to the spade flasks, 2-94—39C and 39D. The condition of the bolt holes in the flasks may require special spade bolts.
    30. Angle of site mechanism of carriages M1897, M1897MIA2, and M1897A4.—a. General.—The angle of site mechanism controls the angular relation of the rocker and the trail. Description and detailed information on the angle of site mechanism are given in TM 9-305.
    b.	To dismount angle of site worm gear shaft.—(1) Take out the gear cover screw, 2-94-57E (fig. 9), and lift off the cover, handwheel shaft, and pinion. Slide the gear cover key, 2-94—57B, to one side.
    (2)	Take out the worm gear case plug locking screw and tag it; unscrew the angle of site worm gear housing plug, 2-94-53E (fig. 9), and drift the angle of site gear up through the worm clear of the gear case.
    (3)	Remove the worm gear housing and worm gear shaft (par. 29a).
    c.	Angle of site pinion (at handwheel) worn.—Replace. Same procedure as outlined for the traversing pinion (par. 31e).
    d.	Angle of site gear too low, leaving bevel gears loose.—Replace rhe upper bushing, 52D.
    e.	Angle of site gear case loose and key loose in cover.—The gear case, 2-94—52E (fig. 9), screws into the worm gear housing. 2-94—53G. and its shoulder should contact solidly with that of the housing when the handwheel shaft comes parallel to the axle. The headless gear case locking screw, 2-94-52C, prevents unscrewing the case. Should the gear case become loose, enough metal is faced off the underside of the shoulder to allow the assembling of a steel washer, 1 mm thick, under the shoulder. If the key is loose in its seat, weld stock on side of key for a distance of % inch from the ends and then fit to slots so that it will be necessary to drive it lightly in place. If the gear case cover persists in being loose, face off the shoulder of the cover screw adjacent to the threads.
    f.	To test planeness of sight bracket seat on left rocker arm.—Use a surface plate with red lead, prussian blue, or similar marking material and true up the surfaces with a file or scraper. The seat should be perfectly flat to get good contact with the sight bracket and should have its surface perpendicular to the cradle trunnion. The sight bracket nut. 2-94—55E, must screw on the threaded stud of the sight bracket seat without undue friction and must not be loose as evidenced by end play. If the stud is worn, true it up carefully and try a spare nut. If the spare nut is loose, return the rocker to the shop for a new stud.
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    31. Traversing mechanism.—a. General.—Description and detailed instructions on the traversing mechanism are given in TM 9-305. The axle mounting sleeve, 6 (fig. 40), should be used when reassembling an axle to guide the axle through the bearings. The tapered end of the sleeve will prevent damage to gaskets, bearings, and the threads of the traversing nut.
    b.	Axle traverses hard.-(l) The axle housing or axle bracket may be distorted or the axle bent. (See par. 29/.)
    (2)	The threads of the traversing nut may strike high spots in the bottom of the axle thread spaces. The rubbed spots will show and may be carefully dressed down with a smooth file. This fault is not unusual.
    c.	Axle collars loose on axle.—Fit oversize key.
    d.	Lost motion in traversing mechanism.—Repairs are necessary as soon as it exceeds a sixth of a turn of the traversing handwheel. If due to wear of axle housing bushing, or ends of traversing nut. the replacement of the housing bushing and nut requires the dismounting of the left axle bracket. (See par. 29(7.) When ready to reassemble the axle bracket, determine the thickness of the traversing nut thrust washers by the use of special test washers (fig. 40) as follows: Remove the traversing handwheel shaft, leaving hi place the intermediate gear and bushings. Hold the bracket in a vise with its inner face turned upward, place in the bracket a left traversing nut thrust test washer of medium thickness, set the new nut against it, and try the fit of the gear teeth. Beginning will a test washer obviously too thin, try successively thicker washers until the gears have the slightest perceptible play. Lay aside the traversing hut and measure the distance between a straightedge held against the inner face of the bracket and the right face of the tentatively accepted left test washer by stacking up the special thickness gages, 5 (fig. 40). Return to the carriage, place a trial test “right traversika nut thrust test washer" against the shoulder of the axle housing bushing, 2-94-39E (fig. 8), and follow it with the traversing nut Lay a straightedge, thin enough to pass between two teeth of the geai wheel, against the outer face of the traversing nut and endeavor to pass the stack of thickness gages previously determined between the straightedge and the face of the trail side plate. Begin with a right test washer obviously too thick and decrease the thickness progressively by 0.3-mm and adopt provisionally the first washer that will not allow the passage of the thickness gages. Assemble the whole mechanism, including the axle, and bolt the bracket tight with three or four bolts. Change the test washers, if necessaryfto
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    obtain finally thickness which results in the least possible lost motion, which must not exceed one-eighth turn of the handwheel. Then take out the test washers and replace them with steel washers of the same thickness, made by facing down, if necessary, the thick repair washers, 2-94-70F and TOD, listed under special spare parts for field repair.
    e.	Excessive wear of traversing pinion. 2-94—580 (fig. .9), causing looseness on the traversing handwheel shaft.—This will show usually when the gears do not run smoothly, but will chatter. To replace the pinion, take out the locking screw and unscrew the shaft nut. 2—94—58K. Unscrew the gear cover screw, 2—94—57E, and remove the gear cover. Lift off the handwheel shaft and pinion assembly. Before replacing the new pinion, examine the outer face of the hub of handwheel for wear. Assemble a new handwheel if the pinion protrudes beyond the face of the hub. If the shoulder on the handwheel shaft, 58A, does not protrude just enough beyond the end of the pinion to allow the pinion free movement without end play, replace the shaft. Examine the rivets securing the shaft brace to the handwheel shaft to see that they are tight. This fault is not unusual.
    32. Brake mechanism, wheels, and shield of carriage M1897MIA2.—a. G-eneral.—Description and detailed instructions on the dismounting and replacing of the brake, wheels, and shield are given in TM 9-305.
    b. Brake operating mechanism pertaining to 1h-mm> gum carriage Ml891M1A2.— (1) Brake worm quadrant shaft socket nut. 2-94-33Q (fi,g. 8), damaged. cover lost.—-Use a new nut and adjust it so as to bring the cover pivot to the top. The weight of the cover tends to keep it closed. It may be necessary to file the face of the nut to bring the cover around. Spare nuts, 2-94-72A, having extra thickness to provide for this fitting and extra long cover pivots, 2—94-70G, are issued under special spare parts for field repair for use where the regular nut or pivot does not work satisfactorily. Make sure the cover pivot is properly riveted.
    (2)	Brake worm, quadrant cover, 2-94-31F (fig. 8). loose.—Take out the locking screw and screw cover in tight. Mark and tap a new hole for the locking screw. Cut out a new bevel to clear the worm. The worm must be out before the cover can be removed.
    (3)	Brake worm, support. 2-94-4OF (fig. 8), loose.—The support screws into the brake worm quadrant housing, 32A. and its position when tight against the brake worm support washer 2-94-31K, should be such that the hole for the bolt matches that in the housing. Use a
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    GUN AND CARRIAGE, 75-MM, Ml 897	32
    worm support washer of the right thickness for this. A spare washer, 2—94-72C, provides the extra stock necessary. If the brake worm is then tight in the support, take a little metal from the flat side of the bronze brake worm thrust block, 2-94-31N (fig. 8).
    (4)	Brake worm shaft.—The brake worm shaft was formerly made in sections, the worm quadrant bracket being a separate part screwed into the shaft with a square right-hand thread. Some carriages having this construction are still in the service and note should be made of the condition of this joint whenever the carriage is taken down or opportunity offers.
    (5)	Brake worm quadrant housing lock screws loose.—Assemble new locking screws or if necessary make oversize, screws sufficiently tight.
    c.	Slide rack mechanism.—(1) To dismount pawl shaft.— (Note that the slide rack pawl, 2-94-34C, and the pawl lever, 2-94-34K (fig. 2), lie nearly in the same plane.) Pull the cotter pin from the collar on the left end of the pawl shaft and the paw] shaft will come out to the right. To assemble a new pawl shaft put the lever on the shaft as nearly as possible in the plane which passes through the diagonals of both the square lever seat and the hexagonal pawl seat of the shaft.
    (2)	Pawl loose on pawl shaft.—The hub of the pawl is probably stretched. If no new pawl is at hand, the old one may be heated to cherry red and closed in. In refitting the pawl do all the filing in the pawl and none on the shaft except that the corners of the. hexagon on the shaft may be lightly dressed so that the bearing is on the flat faces. The fit should be tight.
    (3)	To dismount slide rod.— (a) Take off the slide rack nut and drop the compensating beam. Note the slide rod locking screw. 2-94-35L, lying vertically in the slide rod support, rear, the upper end being bent. Straighten it and unscrew from below. Remove the slide rod stud nut, 2-94-35K, from the front end of the slide rod and the slide rod screw, 2-94-35D, which enters the rear end of the slide rod through transom No. 4, 2-94-20E. The rod can now move to the rear and be taken out. In reassembling do not overlook the small pin in the slide rod stud which enters a notch in transom No. 2.
    (b) If the slide rod is made in two pieces, these can be removed by removing only the slide rod screw and stud nut.
    (4)	To disassemble tie.rod shackle.—Punch out the two rivets which hold the shackle in the tie rod block and drive out the shackle. The rivets should have a good tapping fit in their holes.
    449370°—42---5
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    d.	Maintenance of wheels.— (1) Field repairs to wheels are practically confined to tightening hub and tire bolts, renewing liners, and repainting.
    (2)	Hub and tire bolts should be kept tight at all times. Aftertightening up the nuts, the bolts should be slightly peened over to prevent movement or loss of the nuts.
    (3)	When the wooden wheels of the gun carriages become unserviceable they will no longer be shipped to arsenals for repair. When these wheels have reached a state where local repairs cannot be economically effected, they will be disposed of in accordance with existing regulations governing the disposition of unserviceable property.
    (4)	The hub of the French manufactured 1.334-mm wheel will no longer be reamed for the one-piece hub liner. C212. French manufactured wheels that have been fitted with a one-piece hub liner may have unserviceable liners replaced as long as the remainder of the wheel is serviceable. Otherwise these wheels will be disposed of in accordance with existing regulations governing the disposition of unserviceable property.
    (5)	The hub of the American manufactured 1.334-mm wheel is reamed to the correct size and tapered to take the one-piece hub liner. C212. To renew the hub liner, turn the wheel, large end of the liner down, inner end of the hub resting on a solid block of wood, and drive the old liner out with the hub liner driving tool. 12 (fig. 39). Clean and lightly oil interior of the hub before tapping the new liner into place with a block of wood.
    (6)	A fairly efficient replacement of a spoke can be made in the field. Take out the hub ring carriage bolt which holds the particular spoke to be replaced. Saw the old spoke into two or three pieces and get it out of the wheel. Detach the spoke shoe and spoke shoe plate. Make the new spoke about %2 of an inch longer than the old one, bevel the hub end on the inside so that it can be driven in, and tightly wedge the other Spokes together just as the end strikes the barrel of the hub box. Slip the spoke shoe over the outer end of the spoke and give the inner end a coat of white lead. See that the opening in the hub box is clean. Enter and drive home the spoke. Drive in the spoke shoe plate (it may be necessary to take off the end of the spoke to get room), put white lead on all the surfaces covered by the spoke shoe, bring the spoke shoe into place and set the rivets. Cut the hole for the hub box carriage bolt so that the bolt in bearing against the wood tends to force the spoke toward the wheel center.
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    GUN AND CARRIAGE, 75-MM, Ml 8 97	32-34
    (7)	The encl play of the wheel is taken up by varying the thickness of the axle washers and by taking advantage'of the steps on the axle cap. Before a carriage leaves the ordnance repair shop, sufficiently thick axle washers will have been assembled to take up the end play allowed by the lowest steps of the axle cap.
    (8)	It is prohibited to soak a wheel in water to tighten the fellies. I he wheels should be kept well painted to exclude water. A water-soaked wheel soon dries out and becomes worse than it was before being soaked.
    e.	Maintenance of shields.— (1) There are three types of shields, the description and detailed instructions on the dismounting and replacing of which are given in TM 9-305.
    (2) The openings in the shield and apron latch staples wear large. Whenever the regular shield or apron latch keys are found too loose, the oversize key should be fitted. These keys must be ground for fitting as they are too hard to file. See that the thongs are assembled in the apron latch keys.
    (3) Shields must not be heated. If they cannot be straightened cold, replace with a new shield.
    33. 75-mm gun carriage M1897A4.—Description and detailed instructions on the dismounting and replacing of the high speed adapter are given in TM 9-305.
    34. 75-mm gun carriages M2 Al, M2A2, and M2 A3.—a. Top camage.—The top carriage is of built-up and welded steel construction. Maintenance of the top carriage consists mainly of noting cracks that may develop in the welded joints. If appreciable cracks should develop to the extent of i/4 inch each side of the weld, and if when tapped with a hammer it does not sound solid, and if parts are subjected to firing stresses, the carriage should be withdrawn from service.
    5. Bearings.—The gun and recoil mechanism are housed in the cradle which pivots in the trunnion bearing of the top carriage. These bearings should be removed and examined for burs and scoring. If the ball and cup have a series of scored places they should be replaced by new parts.
    c.	Elevating mechanism.—Lateral adjustments of the elevating worm are made by means of the ball bearing retainer, A138027 (fig. 20), which is assembled in the elevating gear case and which bears against the ball bearing assembled on the end of the elevating shaft gear, B107043. The adjustment made by the ball bearing retainer is secured by means of the ball bearing retainer lock screw which engages a slot in the retainer.
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    d.	Traversing mechanism.—Control of maximum traverse is by means of stops, one on each end of the traversing rack. The screw holding the stops to the traversing rack should be replaced if bent.
    e.	Equilibrator.—(1) In replacing the spring in the equilibrator it is necessary to depress the cradle until it is possible to assemble the equilibrator assembling nut, A137149 (fig. 23), its full length on the equilibrator rod. (Spring pressure is approximately 1.200 pounds in this position. Measure the distance from the top of the equilibrator to the bottom face of the trunnion of the equilibrator trunnion pin, A141451. Elevate the cradle and remove the equilibrator trunnion pin and then the equilibrator assembly.
    (2)	If an arbor or drill press is not available for disassembly of the equilibrator, equipment should be made locally for its disassembly. The equipment should consist of two %-inch by 6-inch square steel plates drilled at each corner to receive a %-inch by 44-inch steel rod. and in the center a hole drilled large enough to pass over the equilibrator assembly nut. The rods are to be threaded on one end to receive a %-incli nut and the other end to be threaded about 12 inches to receive %-inch nuts.
    (3)	Set the equilibrator in the fixture and screw the nuts on the rod until the plates bear against each end of the equilibrator. Then remove the equilibrator assembly nut, A137149. Unscrew the %-inch nuts on the long threaded end of the rods until all tension of the equilibrator spring is released.
    (4)	Reassemble the equilibrator in the reverse order of disassembly.
    (5)	After assembling the equilibrator assembly in its position on the carriage, assemble the equilibrator trunnion pin in the same position as before disassembly and screw the equilibrator assembly nut its full length on the equilibrator rod.
    (6)	Depress the cradle until the equilibrator trunnion pin is seated in its bearing, and then remove the equilibrator assembly nut from the equilibrator rod.
    f.	Brake.—The procedure for adjusting the brakes is as follows:
    (1)	Set hand brake lever at full release position.
    (2)	Jack up wheel. Adjust the adjusting wedge by means of a wrench until a drag is felt on the wheel.
    (3)	Then back off the adjusting wedge just enough so that brake does not drag.
    (4)	Brakes must be cold when making adjustment.
    (<>) I he position of the brake lever can be adjusted bv removing it fiom its splined shaft and setting it in a different position on the shaft.
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    35.	Diffeiences between sights of French and American manufacture of M1897, M1897MIA2, and M1897A4 gun carriages. a. (1) Ihe auxiliary angle of site levels of French manufacture are inclined at an angle of 200 infantry mils, while those of American manufacture are inclined at an angle of 200 artillery mils.
    (2)	The angle of site scales on sights of French manufacture are giaduated in infantry mils, while those of American manufacture are graduated in artillery mils.
    (3)	Ihe elevation scales on carriages of American manufacture are graduate in artillery mils and meters, while those of French manufacture are graduated in meters only. The French scales are being modified when carriages are overhauled.
    (4)	The deflection drum on sight brackets of both French and American manufacture are graduated in artillery mils.
    b.	An inclination of 200 infantry mils is 11°27'32". An inclination of 200 artillery mils is 11°15'. The difference is 12'32".
    c.	In testing and adjusting the sights, all of the differences noted, with the exception of the auxiliary angle of site levels, will be disregarded.
    d.	Ihe setting of the sight on the 75-mm gun and carriages M1897 M1897MIA2, and M1897A4 is the most difficult field maintenance operation carried out on field artillery. However, when it is thoroughly understood it is relatively easy, but at no time does it become a maintenance problem that can be entrusted to any but the best of workmen. After the artillery section has been put through several days’ training, it would be well to choose four or five men who have shown the best mechanical ability and a knowledge of elementary algebra, and give them special training in sight setting. Before the set ting of the sight can be correctly performed, a number of facts will have to be known. Due to the inaccuracies in manufacturing and othei causes, all sights and levels contain inherent errors which cannot be removed but can be compensated for if they do not exceed certain limits.
    e.	The following information will have to be obtained before the sight can be correctly set:
    (1)	Accuracy of the master level.
    (2)	Accuracy of the line sights with the bore of the gun.
    (3)	Trunnion friction.
    (4)	Errors in the sight.
    (5)	Error in the angle of site level.
    (6)	Lost motion of the deflection drum.
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    When the above information has been obtained the following must be determined:
    (1) Sight bracket adjustment for elevation.
    (2) Sight bracket adjustment for deflection.
    36. Master level test.—a. The master level, 4 (fig. 45). is a sensitive instrument and should be corrected each time before being used. With the master level key in place and the indicator set at zero, place the master level on the leveling plates of the gun. Elevate the breech until the bubble is centered between the lines on the level vial. Turn the master level end for end. If the level is properly adjusted, the bubble will still be centered. If not, center the bubble by means of the indicator.
    b. The reading on the indicator will be twice the error of the level. If it exceeds Ti/ (one-fourth of a minute) the level should be adjusted.
    c. To eliminate the error, set the indicator at one-half the error noted and center the bubble of the level by elevating the breech. Set the indicator at zero and center the bubble by the adjusting screw, then the level will be properly adjusted. The adjusting screw is in a recess in the level foot directly under the indicator and is locked by a screw in the end of the level.
    37. Testing line sights.—a. Set up the testing target approximately 54 yards from the gun. Have the target about 3 feet higher than the gun and true with a plumb line.
    b. With the gun pointed in the direction of the target, level the axle, jacking up one wheel if necessary. The wheels should be on hard ground or a firm base of some description.
    . By means of the range crank, operate the elevating mechanism so as to raise the breech and bring the axis of the bore, by means of the bore sights, on the bore sight of target without overpassing the position, that is, without having to lower the breech after having raised it.
    (2) Place the master level, 4 (fig. 45), on the leveling plates of the gun with the indicator to the rear, remove the master level key, place the indicator at zero, and turn the thumb nut so as to bring the bubble between the index lines. Raise the breech by two or three turns of the crank, then lower it slowly so as to again bring the bore on the target without overpassing the position. Turn the indicator of the master level without touching the thumb nut and bring the bubble between its index lines. The angle, or the reading of the indicator, so found, is the measure of cradle trunnion friction.
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    ORDNANCE DEPARTMENT
    (3) This defect is reduced by a careful cleaning of the wearing parts, trunnion bearings, caps, half bearings, by using very fine emery cloth on rusty ami painted surfaces, and by a careful dressing down of burs and high spots.
    d. (1) Set the range scale at about 1,000 meters and the angle of site at zero. These figures are not compulsory but will be found convenient as angle readings are sure to be positive.
    (2)	By means of the angle of site handwheel, raise the breech (it may be sometimes necessary first to lower and then raise) so as to bring the bubble of the angle of site level between its index lines, without overpassing the position, that is, without having to lower the breech after having raised it. Otherwise, the operation has to be repeated.
    (3)	Place the master level, 4 (fig. 45), on the leveling plates of the gun with the indicator to the rear, remove the master level key, place the indicator at zero, and turn the thumb nut so as to bring the bubble between the index lines.
    (4)	Leave the master level in place on the leveling plates.
    (5)	Raise the breech by two or three turns of the angle of site handwheel, then lower it slowly so as to bring the bubble of the angle of site level between its index lines without overpassing its position.
    (6)	Turn the indicator of the master level without touching the thumb nut. and bring the bubble between its index lines, 'fake the reading of the indicator.
    (7)	The angle, or the reading of the indicator, so found, is the measure of the trunnion friction. If this reading is not greater than 3' (3 minutes), the condition is acceptable, but if time permits, it should be reduced as much as possible.
    39.	Testing sight.—a. As previously stated, all sights have inherent errors. There are errors for elevation and deflection, and to be able to adjust the sight to the gun, these errors must be known. They are determined by comparison with the master service sight, the errors of which are known. Before taking up this test, the following facts should be understood:
    b.	When the master sights, 3 (fig. 44). are received, it will be found that one of the sights has its known elevation and deflection errors engraved on the flat surface of the sight shank directly below the rear end of the collimator, in characters approximately % inch high. (Example : E = +0.7 minute. D= —0.0 mil.) The other master sight is unmarked, as the measuring of the errors of this sight is performed in the field. The engraved sight is known as the master test sight, the other as the master service sight. The master test sight should
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    GUN AND CARRIAGE, 75-MM, Ml897	39-40
    be used only for testing the master service sight and the master service sight for testing the battery sights. Both sights should be handled carefully and always carried in their proper places when not in use. I he master test sight should be returned to an arsenal for correction about every 3 months during the time of war and about every 6 months in time of peace. In peacetime the master service sight should be compared with the master test sight each time before being used, and about every 2 weeks in time of war.
    c.	The error of a sight, the line of which points too high, is expressed with the minus (-) sign, as it causes the gun to point too low. If the sight line points too low, it is expressed with the plus ( + ) sign, as it causes the gun to be pointed too high. 'These are the elevation errors and are expressed in minutes.
    d.	If the sight line points to the left, it is expressed with the plus ( + ) sign, because it causes the gun to point to the right. If the sight line points to the right, it is expressed with the minus (—) sign, because it causes the gun to point to the left. These are deflection errors and are expressed in mils.
    e.	Testing the master service sight is carried on by comparison with the master test sight in exactly the same manner as for measuring the errors of the battery sight (par. 40) with the exception that, as greater accuracy is required, nine comparisons are made instead of five.
    40.	Testing battery sight for elevation.—a. ‘With the gun and testing target set up as explained in testing the line sights (par. 37), remove the angle of site level and put in place the level testing seat, 8 (fig. 45).
    6.	Place the master service sight, 3 (fig. 44). in the sight bracket and set the angle of sight dial at zero. Set the deflection drum at 100. and lay the sight on its corresponding target of the testing target by elevating the breech with the angle of site handwheel.
    c.	Set the indicator of the master level. 4 (fig. 45). at zero and place it on the level testing seat with the indicator to the rear. Center the bubble of the master level by means of the angle of site worm wing knob. This marks the position of the master service sight.
    d.	Remove the master service sight, put in place the battery sight, and bring the sight on its target as was done with the master service sight. Center the bubble of the master level by means of the indicator. Take the reading of the indicator and record it with its sign.
    e.	Repeat the operation with the two sights five times, recording each reading. The mean of the five readings will give the relative
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    ORDNANCE DEPARTMENT
    error of the battery sight. However, the master service sight has an error, and to get the absolute error of the battery sight this error must be’ added to it algebraically. For example, the known error of the master service sight is +0.2' (plus %0 of a minute), and the relative error of the battery sight is -0.3' (minus %0 of a minute). This will give a correct error of —0.1' (minus y10 of a minute) for the battery sight.
    /. An error not to exceed ±3' (plus or minus 3 minutes) is permissible. Rule for adding two algebraic numbers:
    (1) If the numbers have like signs, find the sum of their absolute values, and prefix the common sign to the result.
    (2) If the numbers have unlike signs, find the difference of their absolute values, and prefix the sign of the greater number to the result.
    g. In comparing the master service sight with the master test sight, the operation is carried out nine times, as greater accuracy is required.
    41. Testing battery sight for deflection.—a. With the testing target and the gun set up as for the elevating test, put in place the master service sight, 3 (fig. 44), and set the deflection drum at 100 by rotating from zero to 100 without passing the index line.
    1). Lay the sight on its corresponding target of the testing target by means of the traversing handwheel. This marks the position of the master service sight.
    c. Remove the master service sight and put in place the battery sight. Bring the battery sight on its target by rotating the deflection drum knob from 0. Do not pass the final setting and do not use the traversing handwheel for this part of the test.
    (I. Take a reading on the deflection drum and record it. Repeat this operation with both sights five times, recording each reading. Determine the mean reading. Record the difference between the mean reading and 100, using the minus ( —) sign if the mean reading is below 100, and the plus ( + ) sign if it is greater than 100. For example, if the mean reading is 98 mils the value to be recorded is — 2 mils. The result is the relative deflection error of the battery sight with respect to the master service sight.
    e. To get. the absolute error, the known deflection error of the master sight must be added algebraically.
    /. An error not to exceed ±2 (plus or minus 2) mils is permissible.
    g. In comparing the master service sight with the master test sight, this operation must be carried out nine times, as greater accuracy is required.
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    42.	Angle of site level test.—a. Place the level testing seat. 8 (fig. 45), on the leveling plates of the gun.
    b.	Place the angle of site level on the level testing seat with the cover open to the left. This is the position in which it sets on the sight bracket.
    c.	Bring the bubble of the angle of site level between its index lines by means of the angle of site handwheel.
    d.	Remove the angle of site level and the level testing seat.
    e.	With the master level key in place, set the master level. 4 (fig. 45), on the leveling plates of the gun with the indicator to the rear.
    f.	Level the master level by means of the indicator.
    g.	The reading of the indicator with its sign will be the error of the angle of site level.
    43.	Auxiliary angle of site level test.—The auxiliary angle of site levels of French manufacture are inclined at an angle of 200 infantry mils (ll°2t 32 ), those of American manufacture are inclined at an angle of 200 artillery mils (11°15'), the difference being 12'32".
    a.	French manufacture.—(1) Place the auxiliary level testing seat (11°27'32"), 6, (fig. 45), on the leveling plates of the gun.
    (2)	Place the auxiliary angle of site level (11°27'32") on the auxiliary level testing seat in the same position in which it sets on the sight bracket.
    (3)	Bring the bubble of the auxiliary angle of site level between its index lines by means of the angle of site handwheel.
    (4)	Remove the auxiliary angle of site level and the auxiliary level testing seat.
    (5)	With the master level key in place, set the master level, 4 (fig. 45). on the leveling plates of the gun with the indicator to the rear.
    (6)	Level the master level by means of the indicator.
    (7)	The reading of the indicator with its sign will be the error of the auxiliary angle of site level.
    b.	American manufacture—Using- the auxiliary level testing seat (11°15'), 7 (fig. 45), test the auxiliary angle of site level (11°15') in the same manner as prescribed (a above) for testing the auxiliary angle of site level of French manufacture.
    44.	Testing sight bracket for lost motion of deflection drum. a. If the lost motion of the deflection drum exceeds 4 mils, the sight bracket cannot be used.
    b.	Place, the gun in the center of the cradle, using the following method: Place a screw driver between the side of the recoil mechanism
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    and the sweeper plate and pry the gun as far to one side as it will go, then back as far as it will go to the other side, then to the center of the two extreme positions.
    c.	With the testing target in position as described in the preceding tests, put the master service sight, 3 (fig. 44), in the sight bracket.
    d.	Lay the line sights of the gun on their corresponding target on the testing target.
    e.	Bring the vertical line of the sight on its corresponding line on the testing target by revolving the deflection drum from zero.
    /. With a sharp pencil and the deflection drum index scribing guide, 3 (fig. 45), draw a line on the sight support opposite the 100 division of the deflection drum.
    g.	Revolve the deflection drum until the 200 division is reached, then in the opposite direction until the vertical line of the sight again rests on its line on the testing target.
    h.	As before, scribe a line with a pencil opposite the 100 division.
    i.	The distance between these two liners represents the lost motion of the deflection drum. If it exceeds 4 mils, the sight bracket cannot be used.
    j.	Revolve the deflection drum so as to bring the 100 division midway between the two pencil marks and draw a third line.
    k.	To this line add algebraically the known deflection error of the battery sight.
    Z. This position will indicate the index line to be scribed on the sight bracket for the zero position of the deflection drum. However, do not scribe this line permanently until the test for elevation has been made, as that test may show that the sight bracket will have to be changed. After the test for elevation is made, if it is found that the sight bracket can be used, the line must be permanently scribed.
    45. Testing sight bracket for elevation.—a. This test is intended to determine errors in laying for elevation due to defects of the sight bracket, or its adjustment on the seat of the rocker arm. The adjustment will not be undertaken if the trunnion friction exceeds 3' (3 minutes) or the lost motion of the deflection drum exceeds 4 mils.
    b.	The test requires the working out of an algebraic example such as is shown in example A (table of examples, par. 48). In going through this test the first time, it will be well to have example A before you and to use the figures shown on it instead of the actual figures obtained.
    c.	As the sight and angle of site level are both on the sight bracket, and are both moved when the angle of site handwheel is turned, they
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    both have to be taken into consideration in this test.* It must be remembered that the errors of both have been determined in preceding tests.
    d.	As the test is for elevation, the deflection need not be taken into consideration.
    e.	The gun and testing target being in position as previously described, place the battery sight in the bracket and the angle of site level on the level holder.
    f.	Set the range scale at zero (do not use the range rack), the sight at zero and the deflection drum at 100.
    g.	Lay the bore sight on its target of the testing target by elevating the breech with the angle of site handwheel. If the target is passed, lower the breech and start again.
    A. Place the master level, 4 (fig. 45), with the indicator to the rear, on the leveling plates of the gun. Remove the master level key and set the indicator at zero.
    i.	Turn the thumb nut of the master level so as to bring the bubble between the index lines. Leave the master level on the leveling plates of the gun and lower the breech by two or three turns of the angle of site handwheel.
    j.	Raise the breech until collimator sight rests on its corresponding target of the testing target, If the target is passed, lower the breech and start again.
    k.	Turn the indicator of the master level until the bubble is centered. Do not touch the thumb nut. Take the reading of the indicator and record it with its sign, say for instance +0.3'.
    Z. Again lay the bore sight on its target of the testing target, Set the master level indicator at zero and center the bubble by the thumb nut. Raise the breech by means of two or three turns of the angle of site handwheel.
    m. Lower the breech until the collimator sight rests on its target of the testing target, Do not pass the final point,
    n.	Turn the indicator of the master level until the bubble is centered. Do not touch the thumb nut. Take the reading of the indicator and record it with its sign, say for instance +0.9'.
    o.	It will be noted that one reading was obtained by raising the breech and one by lowering it. This is done to get the mean point of friction that may remain in the angle of site mechanism.
    p.	Set the angle of site worm wheel index at zero. By lowering the breech two or three turns with the angle of site hand wheel, then raising it, bring the bubble of the angle of site level between its index lines.
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    ORDNANCE DEPARTMENT
    q.	Put the master level key in position and center the bubble by means of the indicator. Take the reading of the indicator and record it with its sign, say for instance, +0.1'.
    r.	Bring the bubble of the angle of site level between its index lines by first raising and then lowering the breech by means of the angle of site handwheel. Center the master level bubble by means of the indicator. Take the reading of the indicator and record it with its sign, say for instance, +1.1'. This will give an example like the one shown in example A. column 3 (par. 48).
    s.	By taking the mean of the sight readings N, +0.6' is obtained as shown in column 4. By the same method the level reading L. +0.6' is obtained.
    t.	This has to be further corrected, however, as in column 2, it is shown that there is a known error of —0.6' for N (obtained from par. 41) and +1.3' for L (obtained from par. 43). By subtracting column 2 from column 4 algebraically, a mean reading after correction of known errors is obtained for N of +1.2' and —0.7' for Z, as shown in column 5.
    u.	By subtracting L from 8 algebraically and dropping the sign, error B of the sight bracket is obtained in column 6.
    v.	For example A shown in table of examples (par. 48), S is +1.2'. L is —0.7', and B is 1.9'. Since these values are within the limits shown below, no adjustment is necessary.
    V). The limits of errors allowed are—
    For N, ±3' (plus or minus 3 minutes)..
    For Z. ±2' (plus or minus 2 minutes).
    For B. 3' (3 minutes).
    x. Should B exceed 6. the bracket will have to be exchanged if another sight or level on hand does not bring it within the prescribed limits. As the permissible error in the sight is ±3' (plus or minus 3 minutes) and the limit to which the angle of site index can be moved is ±3' (plus or minus 3 minutes), it will be seen why the limit of the permissible error in the bracket is six (6).
    y. Before taking up the other examples in which adjustments are required, it will be necessary to understand what adjustments mean and how they are made.
    46.	Adjusting sight bracket.—a. As previously explained, adjusting the sight bracket can be undertaken only if the trunnion friction does not exceed 3' and if the lost motion of the deflection drum does not exceed 4 mils. If these conditions are not fulfilled, it is necessary to reduce the trunnion friction, change the bracket, or use another sight or another level that has a different error,
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    b.	Adjusting the bracket consists of two distinct operations:
    (1)	Adjusting the level holder.
    (2)	Adjusting the bracket on the rocker arm.
    c.	Krom the preceding it will be seen that an error can exist by means of the bracket on the rocker arm or of the level holder in the bracket.
    d.	The defect in the bracket itself is shown by error B. If this exceeds 3 , an adjustment is necessary; if it exceeds 6. see paragraph 45a?.
    e.	As error B is the algebraic difference between errors N and L, it is evident that this error is clue to a defect in the relative position of the sight on the bracket and of the level on the bracket when the angle of site worm wheel is set at zero. To correct the defect, means altering these relative positions, and due to the construction of the bracket this can only be done by altering the zero setting of the angle of site worm wheel by moving the angle of site worm wheel index line.
    /. On account of the eccentric position of the level holder on the angle of site worm wheel, the index line can be moved only to a small extent, the limits of which are determined by the thickness (0.6 mm) of the reference line etched on the bracket to the rear of the index line. Since the divisions of the worm wheel are not equidistant, it is evident that the correction made for the division of zero would not be the same correction necessary for extreme divisions. Therefore, the index line can be displaced only within close limits, beyond which readings made at some distance from the reference line would be too inaccurate. I he limit within which the index line may be displaced is 0.6 mm. Moving the index line 0.6 mm corresponds to an alteration of 3' in the position of the level. Thus 3' is the maximum correction given to error B by changing the position of the level. After correction of L. B should not exceed 3'. A bracket with an error B of more than 6' is beyond correction. The 6-mm reference line is etched on the bracket by the manufacturer and must not be moved. Should a bracket be received on which this line is not etched, the bracket cannot be used.
    g.	It should be understood that a correction of 3' is not always possible. It depends upon the original position of the index line in relation to the reference line. Should the index line be exactly in the middle of the reference line, a correction of only 1%' is possible either way.
    h.	A correction which is intended to elevate the gun means moving the index line up, to depress the gun. down.
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    ORDNANCE DEPARTMENT
    i.	The movement of the index line adjusts the level holder and is made as follows: When the errors of aS, L, and B have been determined, the amount and the direction of the necessary correction in the support will be known. Suppose that the correction of minus 2' has been found necessary, that is. a correction such that the use of a level on the bracket will depress the gun by an additional 2'. Set the angle of site worm wheel scale exactly at zero, remove the angle of site level from the bracket, and place on the level holder the level testing seat, 8 (fig. 45). With the master level key in place, set the index knob at zero, and place the master level, 4 (fig. 45), on the level testing seat and center the bubble by means of the angle of site handwheel. Adjust the indicator at plus 2'. Moving the index line down corresponds to elevating the level holder; then center the bubble by means of the angle of site worm wheel knob. This will lower the zero line of the angle of site worm wheel to the position where the new index line should be scribed. Should the new position of the index line fall outside the reference line, the zero line should be brought to the extreme lower position within the limit. Bring the bubble of the master level between the index lines by means of the indicator. This will then give the maximum correction possible. By reference to the remaining errors in the example it will be seen whether this correction is sufficient to bring error B within the required limits. If the position for the correction is not sufficient, and if another sight and level on hand do not bring it within the prescribed limits, the support will have to be changed. If the correction required has been plus 2Z, the opposite sign would have been used and the index line would have been moved up.
    j.	The defect of the adjustment of the bracket on the rocker arm is shown by errors 8, sight, and L. level.
    k- Adjustment of the bracket on the rocker arm will, of course, change both aS and L the same amount, as shown in example B, columns 9 and 10. Column 9 shows the correction of the bracket on .the support. This correction is added algebraically to aS and L of column 6 giving the new values of aS and L in column 10. If A and L had the same value, a correction would bring them both to zero. As aS and L usually differ, the best correction would be that which brings one above and one below zero about the same amount. The adjustment is made by altering the thickness of the lower shim, which determines the position of the bracket on the rocker arm. This shim is under the tailpiece of the bracket and rests on the bottom lug of the rocker arm.
    /. A correction which is intended to elevate the gun means moving the tail of the bracket up by use of a thicker shim. To depress the
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    gun means moving the tail of the bracket down by use of a thinner shim. A difference of 0.1-mm thickness of the shim corresponds approximately to a difference of 2' in the position of the bracket.
    m. If the correction is intended to depress the gun, which requires the use of a thinner shim, proceed as follows:
    (1)	The consideration of the errors 8 and L will determine the amount and direction of the necessary correction of the bracket on the rocker arm. (This will be explained further on.)
    (2)	Suppose a correction of minus 4' has been found necessary; that is, a correction such that the use of either the sight or the angle of site level on the bracket will depress the gun by an additional 4'.
    (3)	1 his correction may be made by filing down the shim by 0.2 mm. measured with a micrometer, or as follows: Remove the sight from the bracket and place in the sight socket the sight testing seat, 2 (fig. 44). Loosen slightly the upper adjusting screw in the rocker arm upper lug. Loosen the sight bracket clamping nut and the sight bracket center nut enough to allow the bracket to be moved stiffly up and down. I ighten the upper adjusting screw enough to insure contact of the tailpiece on the shim.
    (4)	With the master level key in place, set the indicator at zero and place the master level, 4 (fig. 45), on the sight testing seat with the indicatoi to the rear. I hen center the bubble by elevating the breech of the gun by operating the angle of site handwheel.
    (5)	Release the upper adjusting screw, remove the lower shim and file it down approximately 0.2 mm. At frequent intervals place the shim on the rocker lug. tighten the upper ad j listing screw to insure contact and center the master level bubble by means of the indicator. Ihe reading will give the value of the correction corresponding to the filing of the shim. Thus filing should be (in this case) carried on until the reading is plus 4'. Filing down the shim corresponds to elevating the sight.
    n. If the correction is intended to elevate the gun, which requires the use of a thicker shim, or if a new support is to be put in place, the selection of the shim is to be made as follows:
    (1)	'rhe bracket to be adjusted, or the new bracket, should be held on the rocker arm by the sight bracket center nut, tightened just enough to allow the bracket to rock stiffly.
    (2)	Set the range scale at zero and lay the bore sights on their respective target of the testing target by means of the angle of site handwheel.
    (3)	Raise the sight bracket as high as possible. The collimator sight is then directed below its corresponding target on the testing target.
    449370°-- 42-----6
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    ORDNANCE DEPARTMENT
    (4)	Bring the sight on its target by slowly turning the upper ■adjusting screw.
    (5)	Insert successively between the lower lug of the rocker arm and the tail of the bracket different thickness shims until one is found that is just a little too thick to be used. Use this shim to fix the bracket on the rocker arm. Go through the regular test to get the errors 8, Z, and Z, and proceed for adjustment as previously explained.
    o. The foregoing operation for adjustment of the bracket on the rocker arm should always be followed by a complete new test with the bracket tightly secured to the rocker arm. Very often errors for /S', L. and B will be found, and should they be beyond the permissible limits they will have to be corrected.
    47.	Table of examples in sight testing.—The four examples following are typical of conditions that will be found. Headings of the columns are self-explanatory. (See par. 48.)
    a.	Example A.—As has been stated before, the permissible error allowed for the sight is plus or minus 3', for the angle of site level, phis or minus 2', and for the bracket. 3'. From this it will be seen that the results obtained in this example are within the limits and no adjustment is necessary.	* t
    b.	Example B.—Column 6 shows that error B is within the limits; so no adjustment in the bracket is necessary. Error L is also within the limit, but error S is not. Therefore, the position of the bracket has to be changed which will also change L. As both errors elevate the gun, the correction should be made to depress it. This means moving the tailpiece downward by using a thinner shim. Column 9 shows that changing the position of the bracket by —2.5' brings all errors near the center line of the gun and within the prescribed limits. The value of —2.5' is found by trying different figures and then working out the example to get satisfactory results in column 10. After a reasonable amount of practice, these figures can be guessed so closely that the example need only be worked out once.
    c.	Example C.—As errors L and B are larger than the permissible limits, it is necessary to reduce error L and bring it nearer xS, which would reduce B. By reducing L minus 2' by means of changing the angle of site index, the results shown in column 8 are obtained, which bring all the errors within the prescribed limits.
    d.	Example I).—Column 6 shows that xS and B are larger than the prescribed limits By bringing L nearer xS', as shown in column 7. the results shown in column 8 are obtained. This brings B within and leaves xS greater than the prescribed limits, which necessitates
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    an adjustment of the bracket on the rocker arm of phis 21// for the reduction of 8. This adjustment will then give the results shown in column 10. Thus the errors of N and B are within the prescribed limits.
    48.	Summary.—a. It is important to understand the use of all the handwheels, adjustments, sights, and tools used for the sight bracket inspection and adjustment.
    b.	A careful study and understanding of the testing and adjustment of the sights are necessary before attempting to carry out the procedure.
    c.	Summary of procedure for testing and adjusting sights:
    (1)	Master level test (par. 36).
    (2)	Testing the line sights (par. 37).
    (3)	Trunnion friction test (par. 38).
    (4)	Testing the battery sight for elevation (par. 40).
    (5)	Testing the battery sight for deflection (par. 41).
    (6)	Angle of site level test (par. 42).
    (7)	Testing the auxiliary angle of site levels (par. 43).
    (8)	Testing the sight bracket for lost motion of the deflection drum (par. 44).
    (9)	Testing the sight bracket for elevation (par. 45).
    (10)	Adjusting the sight bracket (par. 46).
    (11)	Sciibe index mark for zero position of the deflection drum (par. 44Z.).
    d.	Error B is obtained by performing the algebraic subtraction between L and N and dropping the sign.
    e.	The values of L and B are changed by adjusting the angle of site level support.
    /. I he value of N is changed by adjusting the sight bracket on the rocker arm. I his also changes L by the same amount as it does 8, thereby not changing the value of B.
    IB The values in column 8 are obtained by the algebraic addition of the value in column 7 to L of column 6. B is then recalculated from 8 and L of column 8.
    h. Changes in the sight bracket setting are shown in column 9. Since these changes affect both 8 and Z, the figure in column 9 is added algebraically to the previous values of 8 and L to give their new values shown in column 10. B is not changed by this adjustment.
    ?. A final check should be made with all sights, levels, and adjustments, making certain that these parts are secured by their respective bolts, nuts, or locking screws.
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    ORDNANCE DEPARTMENT
    TABLE OF EXAMPLES
    Column 10	Mean readings after adjustment of bracket on support	1	CO	r-HI >:	+7 1	sq । । ।		B2?4 >.8- 1. 3 L4-1. 1		B2. 4
    Column 9	Necessary adjustment of bracket on its support	None	 -2. 5 >None	 > +2. 5
    Column 8	Mean readings after adjustment of level support	1	1 i	i	CM	O 1	: 1	4- 1	; 1	1			B2. 2 >8-3. 8 L-l. 4	p za •
    Column 7	Necessary adjustment of level [ support	’N one	 ’None	 -2. 0 -2. 0 ।
    Column 6	Remaining errors	>S+1. 2 L-0. 7	Bl. 9 54-3. 8 L~\~ 1. 4	B2. 4 >8-1. 2 L4-3. 0	CM	00	CO tT	CO	O' 2Q	|	+	i f fa
    Column 5	Mean readings after correction of known errors	+ 1. 2 -0. 7 + 3. 8 + 1. 4 -1. 2 + 3. 0 -3. 8 + 0. 6
    Column 4	Mean readings	1 +0. 6 J +0. 6 - +3. 2 + 2. 2 2. 8 1 4-2. 2 1 ;• -2. 6 } -L0
    Column 3	Readings	Sight— 11st reading -j- 0. 3 ■ 2d reading + 0. 9 Level-— 11st reading 4-0. 1	O rf	X> CO	CO O	N M	O CM	X CM T-i	CO CO	CM	CO CM	r— CO	CO CM	>-i O 4-	4-4-	4—H	II	4—K	II II bC 3 b£ 3 be ¥ bt ¥ «	3 be ¥ tt c	.S	a	.8	q	.a	q	,s	q	.q	q	.8	q 3	I	3	3	|	3	3	i	3	3	1	3	3	I	3	3	|	8	q 1	o	rt	C	53	'	O	03	4	03	1	$	53	4	$	"3 r“>	r-—1	' r*.	r34	£> T5	-SP	a	T5	®	a	-O	m	tJ	®	a	q	a	tJ CM	CM >-4 1-1 CM CQ rt CM	-h CM	CM	rH CM

    Column 1	,	Column 2	Known errors	1 Sight, 0.6	 < .Level, 4-1.3	 'Sight, - 0.6	 < ,Level, 4-0.8	 f Sight, —1.6	 (Level, —0.8	 'Sight, 4-1.2	 .Level, —1.6
    		I	1 Illi 1	1	1	1 <	M	O	Q 0,0	O 3.	o	3.	3. 2	8	8	8 eg X	X	X	X w	a	w	ta
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    49. Special field artillery vehicles.—a. General.—The personnel of the organization to which a vehicle is issued is responsible for its general upkeep and is, therefore, authorized to perform a limited amount of repair work. Detailed instructions for this work appear in TM 9-305. However, through accident and general wear and deterioi ation, conditions will arise which cannot be corrected by such personnel and vehicles will therefore have to be turned over to an ordnance maintenance company. In any event, ordnance personnel vill render all possible assistance in the performance of repair work and will, when necessary, do work outlined in TM 9-305 as well as the special repairs given in b to ) Adapter, 8.—The. adapter, 8, is issued with al] outfits but is
    449370°—42---7
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    ORDNANCE DEPARTMENT
    used only with the 155-mm and 240-mm howitzer materiel.
    ( inches wide, and 18 inches deep.
    1). There are a number of tools provided for the maintenance, repair, and adjustment of the materiel, such as taps, dies, chisels, drifts, files, hammers, pliers, screw drivers, wrenches, and punches, the names or general characteristics of which indicate their uses and application. Therefore, detailed descriptions and methods for their use are not outlined herein. Those tools, however, which are of special design and not commonly used are described and their uses outlined in the paragraphs following.
    52.	Clamp, axle sleeve.—The axle sleeve clamp. 4 (fig. 40), is used to grip the sleeve during disassembly and assembly of the axle.
    53.	Counterbore 4-mm.—The 4-mm counterbore, 7 (fig. 36), is used with the elevating mil collar jig for starting the hole to be drilled in the elevating nut collar when relocating the pin hole.
    54.	Drill, twist, 4-mm.—The 4-mm twist drill, 3 (fig. 36), is used in the elevating nut collar jig for drilling the pin hole in the elevating nut collar when relocating the pin hole.
    55.	Extractor, sweeper plate.—The sweeper plate extractor, 14 (fig. 36) is a hook for aiding in the removal of the sweeper plate and sweeper plate guide.
    56.	File, breech thread.—The breech thread file, 2 (fig. 36), is a special file for smoothing the threads of the breech recess.
    57.	Filler, oil screw.—'The oil screw filler (fig. 37) is used to replenish the oil in the recoil mechanism. For description, use, and operation of the screw filler see TM 9-305.
    100
    TM 9-1305
    GUN AND CARRIAGE, ?5-MM, MI 897	58-69
    58.	Gun, grease.—The grease gun, 9 (fig. 39)i is used for injecting grease into holes Nos. 4, 6,. 9, 10, and 11 of thes carriage. Detailed instructions on lubrication are given in TM 9-305.
    59.	Gun, oil.—The gun, 15 (fig. 3G), is used to force dil into die oiler nozzles on the carriage. Detailed instructions on its use. and operation are given in TM 9-305.
    60.	Jig, elevating nut collar.—The elevating nut collar jig, 9 (fig. 36), is used when relocating the pin hole in the elevating nut collar in changing the collar.
    61.	Nut, assembling, equilibrator.1—The equilibrator assembling nut is an elongated hexagonal nut which is used for retaining the equilibrator as an assembled unit while removing or replacing the equilibrator. This applies to the 75-mm gun carriages M2A1. M2A2, and M2A3 only.
    62.	Puller, gear.1—The gear puller (fig. 47), consists of a plate and three screws, two of which have cotter pins. It is used to remove the elevating worm wheel, B141439 (fig. 20), and traversing worm wheel, B109248 (fig. 21), from their shafts. This applies to rhe 75-mm gun carriages M2A1, M2A2, and M2A3 only.
    63.	Pump, oil, M1A1.2—The oil pump M1A1 (fig. 38) is used to replenish the oil in the recoil mechanism. The oil pump is attached to the right trail and its pipe connection is screwed into the. filling and drain plug hole.
    64.	Reamer, taper (Nos. 1, 2, and 3).—The reamers 4, 5, and 6 (fig. 36) are used in resetting the elevating nut collar pin.
    65.	Roll, tool with contents—The tool roll M4 (fig. 33) contains an assortment of tools for general use in work on the materiel. SNL C-18 lists the proper tools to be carried in this tool roll.
    66.	Screw driver, oiler nozzle.—The oiler nozzle screw driver, 8 (fig. 36), is used only for removing the gun roller oiler nozzles.
    67.	Sleeve, axle mounting.—The axle mounting sleeve, 6 (fig. 40), should be used when reassembling an axle to guide the axle through the bearings. The tapered end of the sleeve will prevent, damage to gaskets, bearings, and the traversing nut threads.
    68.	Tap, 16 by 1.5-mm (PX) (filling and drain plug hole).- The 16 by 1.5-mm (PX) tap, 19 (fig. 41), is used for reresizing the filling and drain plug hole.
    69.	Set, gage hand.-—I he gage hand set, 4 (fig. 35), is used in replacing the gage indicator Hand. when repairs are made to the pressure gage.
    1 lor M2A1, M2A2, and M2A3 carriages.
    2 Common to all carriages.
    101
    TM 9-1305
    70—80	ORDNANCE DEPARTMENT
    70.	Tool, hub liner driving.—The hub liner driving tool, 12 (fig. 39). is used in replacing liners in the hub of wheels.
    71.	Wrench, axle dust washer gland.—This wrench, 3 (fig. 40), is used on the axle dust washer gland.
    72.	Wrench, clamp (elevating nut collar).—This clamp wrench, 1 (fig. 36), is used to turn the elevating nut collar.
    73.	Wrench, hook spanner, 47-mm (worm gear shaft nut).—This wrench, 8 (fig. 39), is used on the angle of site worm gear shaft nut, 2-94-60E.
    74.	Wrench, oil index follower.2—The oil index follower wrench, A7488 (fig. 47), is used in the disassembling or assembling of the oil index follower. It is turned with the handle, A6788.
    75.	Wrench, pintle and trail.1 2—The pintle and trail wrench, B108514 (fig. 47), has on one end an open end wrench used for assembling and disassembling the pintle pin slotted nut, A140574 (fig. 14), and on the other end a hexagonal box wrench used for assembling and disassembling nut. A136607 (trail hinge pin nut). This applies to the 75-mm gun carriages M2A1, M2A2, and M2A3 only,
    76.	Wrench, piston rod nut, front.2—The piston rod front nut wrench, A8765 (fig. 47), is used for tightening the front nut of the piston rod. It is turned with handle. A6788.
    77.	Wrench, socket 24-mm.—The 24-mm socket wrench, 3 (fig. 39), is used on the 14-mm (French) nuts. It is turned with the wrench handle 24-10-LH37L, 4 (fig. 39).
    78.	Wrench, socket, 26-mm.—The 26-mm socket wrench, 2 (fig. 39), is used on the 16-mm (French) nuts. It is turned with the wrench handle, 24-10-LH 37L, 4 (fig. 39).
    79.	Wrench, stuffing box head and follower.2—The stuffing box head and follower wrench, A8161 (fig. 47), is used for adjusting the recoil piston rod stuffing box. It is turned with the wrench handle. 4 (fig. 39).
    80.	Repair tools for special field artillery vehicles.—a. General.—The special repair tools pertaining to special field artillery vehicles are listed in SNI C-18.
    b.	Standard tools— The names of a number of tools required for maintenance, repair, and adjustment of this materiel, such as chisels, drifts, files, hammers, pliers, screw drivers, wrenches, and punches indicate their use. Detailed descriptions of them and methods of use are not outlined herein. Nor are these standard tools included
    1 For M2A1, M2A2, and M2A3 carriages.
    2 Common to all carriages.
    102
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	80
    in the set of special repair tools for the vehicles covered here as they are included in such sets for the various guns and carriages, and in the general equipment of ordnance maintenance companies. Those tools, however, which are of special design and not commonly used are described and their uses outlined in c to o, inclusive.
    c.	Expander.—The expander, 1 (fig. 49), is similar to an expansion mandrel; that is, the outside diameter is increased or decreased by the menchanism assembled inside the expander. The purpose of the expander is to expand the connecting pieces into place in the ammunition chest.
    d.	Expander, short.—The short expander, 6 (fig. 49), is composed of the same parts as the expander, except that the body of the latter is % inch longer. The purpose of the short expander is to hold the connecting pieces rigidly in place, in order that they may be set into the thumb notches of the diaphragm and also act as a guide for the trimming tool (m below).
    e.	Mandrel, driving.—The purpose of the driving mandrel (24-10-47) is to drive the connecting pieces into place.
    /.	Nut, feed.—The feed nut, 9 (fig. 49), is used in conjunction with the trimming tool. Its purpose is to force the ratchet wrench, sleeve wrench, and cone of the trimming tool forward, thus forcing the cutter into the work.
    g.	Pin, adjusting.—The adjusting pin, 4 (fig. 49), is used for turning the long knurled feed nut on the inner and outer expansion rollers.
    h.	Roller, expansion, inner.—The rollers inserted into the cage mounted in the head of the expansion roller. 3 (fig. 49), are operated by the movement of the rear roller shaft, which is controlled by the adjusting nut assembled to the rear roller body and bearing against the crank attached to the rear end of the rear roller shaft. The purpose of the inner expansion roller is to form the bead in the connecting piece just forward of the rear diaphragm and turn the farther end out.
    i.	Roller, expansion, outer.—The rollers inserted into the cage mounted in the head of the expansion roller. 5 (fig. 49), are operated in the same manner as described for the inner expansion roller. The purpose of the outer expansion roller is to roll the bead and set in the front diaphragm.
    j.	Set, square end.—The square end set, 12 (fig. 49), is used to finish the flanging of the connecting piece at the front face of the front diaphragm.
    103
    TM 9-1305
    80-81	ORDNANCE DEPARTMENT
    k.	Set, thumb notch.—The thumb notch set, 11 (fig. 49), is for the purpose of flanging the metal of the connecting piece in the thumb notch.
    Z. Shell, dummy.—The dummy shell, shown on drawing (24-10-55). is for the purpose of resizing and removing the dents in the connecting pieces of the ammunition chest.
    m. Tool, trimming.—The trimming tool. 7 (fig. 49), is for the purpose of removing the surplus stock of the connecting piece after it has been assembled in the ammunition chest.
    n.	Wrench, ratchet.—The ratchet wrench, 10 (fig. 49), is utilized in revolving the expanders.
    o. Wrench, sleeve.—The sleeve wrench, 8 (fig. 49). is used as an extension on the short expander to connect the ratchet wrench with the trimming tool.
    Section VIII
    INSPECTION AND REPAIR OF SPECIAL TOOLS
    Paragraph Inspection and repair of special tools_ ___________________ 81
    81.	Inspection and repair of special tools.
    Condition	Cause	Correction
    a.	Press u r e gage a. Accidental move- a. Repair consists of inaccurate.	ment of the hand pulling the hand off
    upon the spindle, the spindle using the Wear or distortion of gage hand jack (fig. the linkage. Apply- 35), and resetting it in ing pressure suddenly agreement with the causing the band to master gage utilizing strike the stop pin. the p r e s’s u r e gage tester (par. 50z). The most effective readings that are involved lie between 30 and 160 kg. per sq. cm. (430 to 2,300 psi). The m a s t e r gage should be returned to an arsenal periodically for the verification of its accuracy.
    b.	The inspection and special repair tools are of such design that, with proper handling and storage in their respective retainers, they
    104
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, .Ml897	81-82
    A
    should require very little care. Each tool should be inspected before and after use and all burs removed with a smooth file or oilstone. When placed in their container, they should receive a light coat of oil, engine, SAE 30.
    Section IX
    FIELD SERVICE MODIFICATION WORK ORDERS (FSMWO)
    Paragraph Field service modification work orders_:_______ ____ _ _ S2
    82.	Field service modification work orders.—Field service modification work orders are issued from time to time authorizing the modification of materiel. When making inspections and repairs to materiel covered by the manual, it is essential to check the materiel against existing field service modification work orders to keep the materiel up-to-date.
    105
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    SCALE-64E---------------- ---------------ROCKER, ASS'Y
    PLATE - 64A------------------------------  BRACE	- 47C
    CRANK- 62A------------------------------  SHIELD	-45 A
    PLUG - 29C---------- --------------------CAP - 59 C
    THONG-32M---------- r—CAP-38G
    FASTENER-AI59662--
    COUPLER-14 A----	\_____
    '-----------
    TUBE, TRAIL HANDLE, ASS’Y-]	V*	' An)	P . W----------------------- \F»)'
    BRACKET-23D---1 I	TO ,	□ “	3 = Ul----Ja+wH---------------------U=J—1-A
    rLUNETTE, M4-67B	/	&	^)L	____________________I
    / /	YOKE - 6IA-------___________________________________A
    X„	V———	=v|	l-PLATE-AI44092
    J // CRANK-3IA
    FI.OA-22A -	GUARD-44B----,	/ //------H0USING-32A
    ,/V^ _______ — >^^7/ / / \\	----AAyZ //--------HINGE-46U
    SPADE-39A—77	-----BRACKET-23B^gY>A\\V+\ \	// // \\	^/ol//
    —y	0+^ // // \' IX---------------///--------HINGE-46W
    I \\X //	//	\\	\\ 7 //----------APRON-45B
    + SHOE - 28A------1	jJy- XXx
    BEAM-28C	GROUND LINE	RA FSO 2196
    1—GUARD-23Q ---------R0D-30F	---------- --------------------------
    ------ SHACKLE-30D
    Figure 1.—75
    i-mm gun carriage M1897MI right side.
    106
    TM 9-1305
    82
    GUN AND CARRIAGE, 7 5-MM, M1S97
    I--	®	------------------1-----BRACKET - 47A
    SHIELD-45C------------------•	------------------------PIN - 47 F
    SHIELD-48B-------------I----x < v~	-------------J------------BRACE-47C
    HANDWHEEL-56A------------V- ~ I	•-----/-------------SHIELD-45A
    HOUSING - 39B------1---T\\	T	\ /----------1---j--------' YOKE -61A
    CASE-52E---------|r--V Xlhl M	/	/----f----if-------BRACKET-40A
    BRACKET-44A---------\'i	//---/----H---------SHAFT-67A
    BRACKET-4IA---------4-—/ / I JI -----------------------------------------B0X-C209
    HOUSING-53G---------1//	% |	।----CAP-B58I4
    PLUG-42B---x>T	L ) '/Tl WX hIB"------------PIN-A3827
    SEAT - 27B--------f /\ ''zXxfc) --------------------------------------LATCH -A3826
    SHOE-28A------J==	------COLLAR-B5875
    TUBE-29K--------------------------------------------------------------SEAT-27A
    BEAM-28D------P 5r] [Si	/ ■<	Th----‘---BEAM-28C
    SHAFT-26A------ffLU---||	------AXLE-42A
    BL0CK-2IF-------------------zX'l l| / /XZH-----------------------------H0USING-32A
    R0D-30F-------------------i	/ I------------------BRACKET -25A
    BL0CK-30C---------------N.	~r\ ’	---------------LEVER - 34K
    SHACKLE-30D----------------------------------------------------—---------BEAM - 34A
    <	z r---------°\ \
    /	°	o	\
    HANDLE, TRAIL, LEFT, ASS’Y. z	o____o N_ HANDLE, TRAIL, RIGHT, ASS'Y
    -yZ--------SPADE - 39A
    RA FSD 2195
    Figure 2.—75-mm gun carriage M1897MI—rear view.
    107
    TM 9-1305
    82	ORDNANCE DEPARTMENT
    ;-----SCREW-I4B
    f----SIGHT-I4A	,----SIGHT-7C
    I, |-r~PLATE-AI22I5	r—TUBE'IIA
    ; 5
    prjg-H00P-8A
    ' -----CATCH-24A	--------7 SLIDE-230
    PLATE-I4L—->	D-||---N0ZZLE-AI80I5--:-	---CR0SSPIECE-23G
    P-------------------------______________________r-F K-,__________ H-i
    Bn	I
    ,___i______________I A,	1	°1	f
    _	%	|	° i °	°	° o X m	M	r
    -3 i °'iT~"	jt~A<_______-__>’< ....w? w-------------------------vfi/
    \~| J-r 7j	0 0 0 0 6 6 0. •P^,.°.cffgRpAD-| 5L	PLATE - I2H
    jo I	c—1 I-SUDE-23A	BEARING-I9D—1 pE I 1-PLATE-150	G-*
    __	LfiEARING-l9A SLIDE-23E-'	!-B0DY-I7A
    z^^^S-G,J,DE'l2B
    FW	jS9rCROSSPIECE'23G (j B	M )w. [COVER-12A fttf J)ffl
    XAl	iWy^-BEARING-l9E	PLATE-'GA -AAfAA	JjctgWi
    [jr^^nQ-R0LLER-i9K 5r==A>=7jy	flj 7 , 1mholder~i5Dh|T*"Tq
    BEARING-I9A "	^-^BLOCK'ISA
    SECTION A-B SECTION Q-P	SECTION E~F	SECTION J-K	SECTION G~H	MUZZLE END
    0§=jp	TcjJ
    LU--.111	RA FSD 2|86	T -f
    -	Figure 3.—75-mm gun M1897 (French)—sectioned views.
    108
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	82
    109
    r-JACKET —2OAI
    U.
    tost ^a	1 lq cr
    ^^SUPPO^^;60^j-SVProRT-C6^W4|-^UPPORT^eO59^-SUPPORT-CeO592
    // SECTION A-a\\	SECTION B-B SECTION C-C /SECTION D-D
    /% Al L~D30008	\^STRIP-D8096	'L RIVET-AI572O7 RA FSD 2189
    ^-STRIP-DBOGA '-RAIL-D300II
    Figure 4. -75-mm gun M1897A3.
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    --PIN, ASSEMBLY-A25056	_	-----------------PLATE-AI22I5 |STOP~A25O82.	TRIP-B8382	___ -------------[SCREW-A25073
    HsTOP- 27C	SIGHT-I^A	STOP-A 25082	[SCREW-27D
    _ISCREW-A25077	ST0P-27C \	[-PIN-B8378 (24E)
    ISCREW-I4B	\
    PIN, ASSEMBLY-A 25056---?\ j
    £	PIECE - C3749 (26A)--\ Uy. fA/r
    ff	\ HAMMER-03747 (24B)-
    Xu	/Xw\ \ LINK-A25062 (25D)----- kX
    _J / I	\\ % jCATCH-B8374 /\ J ■	~
    || I£Uw^^r™-7h ® vzH I
    Q (Z 1 H M	BREECHBLOCK-617891	I	R
    7 I	V 1 ■ y r*	BREECHBLOCK-I3C I	I	L
    \\ ILBy Jx	[CUSHION-A25058
    soREw-XXwX^ ZF
    SCREW-23N I if| I EXTRACT0R-C3746 %	SCREW-A 25078 u -1	_|SPRING-B8380
    - ■ -- EXTRACT0R-27B X—C0RD-B6722E SCREW' 23 N	■ '''	|SPR|NG-23M
    3™dlEE'2C7A75'	'	-r^G-BBSS,	J0LT-B8372
    LPINDLE-2TA	QANG-I4C	tW	-------
    - HANDLE - A8520	““
    ZUX HANDLE-25 E	RA FSD 2188
    Figure 5.—Breech mechanism—side and rear assembled and sectioned views (75-mm gun M1897).
    HO
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 89 7
    82
    ill
    SAFassembl.y]------iIKm Z7Z <	BURR-A250521/T[ A \\X	/:/ //"/////
    SECTION THROUGH	BURR-25 H]	I I	//////////
    EXTRACTOR TANG	LINK-A250621/A	//////////
    ----------S0LT-23L	PIN-A25064] if	h.PRING-26G —UU- _ (SCREW-A25078	PIN-24HJ pflg? X7 ■ /// ///■' ’ -■ Z	[CATCH-B8375
    I fflh	[SCREW-23N	SCREW-A250751	H	^^1 X^V-Z/Zz/Z z ..	/X [LATCH-26M
    I Hr	JSPRING-B8380	SCREW-24D]	M [f XX
    [SPRING-23M	RACK-C3750I	H	f—THl TTt
    RACK-240 Vi -— 1 l - ' /j—J	ESPRINC—A25080
    OPTION SHOWING	S>RING-A2508fl_ IM /-ZpRING-26L
    S> ETY	SPRING-24G|	; ! kl / pawL_B8J76
    r-EX++	pinp““4||---Il':’ IL""'—™-bpowl
    [LOCK- 26F	H 2 P +^70-^	!CATCH-A25057
    [PIECE-C3749	1	____________ |qrpFW-A25r>fi7
    + PIECE- 26A /-PIN- BFDX3U	c :	.......—-^rL
    \ \	/ /	*X;'j  —-J-—i—'ft >	/'	f
    \\ x- //	------ g-F-___-_xp—-A ___
    S/	rXXXX_( U_______A
    ---B0LT-23L ,rvvvfJ^;dCBa A R0LLER-I9K -\J J vSXJ--; 1	11 ^-KEY-I5B LL^/'	PLATE-I8A--^J	‘ \	/	' JA
    d-- "C0UPLER~14A | PtyptL ■ '	-C0UPLER-I4A	Nk J k Z
    B0LT-23L—z M	--KEY-I5B	\	//
    tSXlwfc.SPRING-23M— \ffllXVZX/Hr— LATCH-I5A	Nd .
    y—	7 x
    SECTION A-B	SECTION X"-Y
    SECTION C-D RA FSD 2|9|
    Figube 4. —Connections between gun and carriage (MIX97MI and M1897MIA2).
    112
    TM 9-1305
    GUN AND CARRIAGE, 7 5-MM, Ml 89 7	82
    SS
    '7C	HOUSING-39BGLAND-44H
    3	BUSHING-39E R//BRACKET-40A GASKET-42H
    /AXLE-42A	BUSHING’44E\WASHER-42G|
    y&w • u	iSr \
    ISLEM-.42C	lT ^71 R A
    ^.2j-A:.2 " ' -jtfrT ' ; '.R1S' ]	I XQ)
    /~~~7	yyyy I	p F0RK-33D Gp I SHAFT ~67A	“ rJ ;
    / /	\ BUSHING-32H lB0LT-32L	' BEARING" 32N	11
    I !	y RING-29G PIN-33E	COLLAR - 32C
    I W	/Z /	/	* HEAD-33H	BUSHING -32F
    \	LEVER-33C	HOUSING -32A'
    W0RM-32E \ -V-	—— SUPPORT-40F
    BLOCK - 3IN	BUSHING - 3IG	RA FSD 635
    QUADRANT- 33A	' NOZZLE - 32D
    COVER- 31 F\©7	TfciJ |-- CRANK-3IA
    SHAFT - 67A^^^■SPINDLE-SlC
    Figuke 8.—Traversing i
    and brake operating mechanism—assembled views (M1897M1 and Mt897MIA2».
    449370°—42----8
    113
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    -------------------WASHER -56D ----------------HANDLE-568 ---------------------HANDWHEEL - 56A ,-------------------------SPINDLE - 56C
    n I —---------------PINION-58C	(fl ft
    t	rrnrl," Sr	HANDWHEEL	-	52A~	+T
    H	-----COVER-56E--------------/d<+toTF^\
    X\	/'-BRACE-58B---------—Ehf—	\\ SHAFT-52K
    l\\ /AfT'toto“KEY-57B-------"-----------NOZZLE - 58G	|
    ZA\ GEAR-530-------	"toF\w~^'' f. "l] PINION-53A---W
    '// J GASE-52E---------------PY	\\
    HANDWHEEL-52A	° StoBUSHING"520 |\\ flT
    // NTll°lnr LAT0H-53H----------------I fl	DX fT[
    // I C ° T1 H0USING-53G--------------Ary-BUSHING-52F	fpL-.
    \C	to---CASE-57A	/	POINTER - 60A—to	S
    'j^~ BUSHING 58E	Jfetx SHAFT-GOG	•' "Ttol
    A 3	C0VER-52N------SHAFT 60G	]ZZZZ
    O' /d -------------GEAR-58D	|	HOUSING-60F---f P-TrnZ
    /	—GEAR-570	W\ ■	JL 4U
    BUSHING-58F	to^ JY \ WORM-53D	PtoA .. TU
    !- z "•	COLLAR-53B----Hj	L PLUG-53E
    NNV^NNAXN mW	SPRING-52M---- - I
    •	.... V / HANDLE-53K--------1 ANGLE OF SITE ELEVATING MECHANISM
    ! toYTtop	—1	RA FSD 2198
    WASHER-56G-----1 T+ L -WASHER-57G
    r uUl ----NUT-56F
    TRAVERSING MECHANISM Figure 9. Traversing and angle of sight mechanism—assembled views (M1S97 and modifications).
    114
    TM 9-1305
    82
    GUN AND CARRIAGE. 75-MM, Ml 897
    SPRING - 67B--------------------
    STOP - 67C-—-------------
    = RACK-65H--------------------\
    PINI0N-64D--\	g GUIDE-63A-----------—----/TUT *3t*7 \
    PJNI0N-64C ■■	= GUIDE-66K——-----------	/ / /	\
    8USHING-64B--\	° / f XW* \
    PINION-68C x	gB .-scale _£4E.-	AgMJJ MWJ \
    \	_/j-'lW-SPR|NG-67G x\
    -----\ JX^WASHER’62K \	\	. -SHAFT - 62H	W ,^"'0 W9 # \	A
    <	-VALVE-67E H f(S)l R I	U
    _____Xs	/4	r----NUT-68B
    :X^-i|^/M~<::0LLAR-68D	iZ)
    •------SCREW-68A	/zSl
    -----	RA FSD 2197
    Figure 10.—Range elevating mechanism—assembled views (M1897 and modifications).
    115
    TM 9-1305
    82	ORDNANCE DEPARTMENT
    r ~T SB TZ
    STRAP - QBDXIAB \ y /.	. .--::-v. J
    WISHBONE - 045202\	//XR’
    \ \ ---jxftO' 'R0D-AI30438
    SEAT - 045205	CLIP'Bl28735
    BRACKET-D28I98B\1	'	' xZR1 rf BRACKET - 0452066
    BRACKET - Bl28734 x " XX	' \ R/ pTR BRACKET-4IA
    BOLT-AI30435] T|	H/SHIELD'SIGHT~ 48B
    SPRING -AI30440 *\ x|	BRACKET - CH3A
    □ygj1E3H	1	n""x—s—y
    Rh c * C u	J—
    N---■ -T	X
    GUARD - 44B —I uRR I Si	BRACKET - 40A
    BRACKET-D28I98A	=	ATTING-CLDXIA
    ■ SHAFT - C45099 -Xyk	LR-— BRACKET - C45206A
    f . ’ \	XyJJ ------AXLE-42A
    V '	---CUP - BI28735
    ---OO, /R0D-AI30428
    ROD - C45204 ■ _____ySIR	rWHEEL, D'lSK
    NUT-AI57225	U-yR R 'AND RIM. ASSY
    k r.--;rtk., -RCy	RA FSD 2205
    Figure 11. -75 mpi gun carriage M1897A4 plan view.
    116
    TIME 9-1305
    82
    GUN AND CARR PAGE, 7 5-MM, MIS 97
    /P^^^/-bi28737 R°D v	y
    AI30430-SPRJNC?	k	&3S,	''T'S--—"
    \ _jLtesS--------------x „______I—
    BI28736-HANDLE-----1	---—U^Z"' ■	1 i
    -- .
    AI304I5-BOLT. SHOULDER] /
    BBBXIB—NUT	\-^ // %\ \	.'
    BECXIH -WASHER,LOCK J // / M \\v7
    BFAXJCC-PIN.COTTER----—y /
    AI304I8-PAWL,BRAKE----/'	' *
    AJ30417-RATCHET, BRAKE—rT=h’"l I I I •
    ------BI28739-LEVER B128742-SHAFT [BCAXIBK- SCREW, CAP /-----B8AX1B-NUT
    1-D28I99B-LEVER	~"r"	*\j _j_ fl / (BECXIH-WASHER, LOCK
    --F- Jy RA Po 4329
    ■ HAND BRAKE ARRANGEMENT	lLp.J
    I
    Figure 12.—Hand brake arrangement—75-mm gun carriage M1897A4.
    IFAXICC—PIN,COTTER
    117
    118
    TM 9-1305
    82	ORDNANCE DEPARTMENT
    ■' ' ' ' ■ .. ' ' '. •.................................................................'■ ; ' .
    BELLEVILLE SPRINGS v	ANTIFRICTION BEARING^	RESPIRATOR----7
    LEATHER WASHER—-Xx	LEATHER PACKING \\ SWEEPER,RECOIL CYLINDER^
    ANTIFRICTION BEARINgX^X	BELLEVILLE SPRINGS\\^\	NUTy	/
    OUST WIPER^	\ \ X. • PISTON ROD^	\.	\\	/	/
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    \	1	MP'	<“3CX
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    yfhSr’—W^ni §» Jl^x,	> 'aX F
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    \	\ X'0IL INDEX PACKING ^REGULATOR	\ FILLING HEAD^
    \	‘Oil. INDEX	^CONTROL ROD	'^FLOATING PISTON
    \ LR£AR COVER PLATE ^COUPLER	RA RD 4958
    Figure 13.—Schematic diagram of recoil mechanism for 75-mm gun carriage M1897, ail types.
    TH 9-1305
    82
    GUN AND CARRIAGE, 75-MM, Ml 897
    CARRIAGE, TOP—j pB OLT-AI5 6024
    AJmwbirww*
    »|»I^IW5iWIW -* J jjriMHMIwr^to, -r, .......	\( ...... -Mf y
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    S	"CORO-B6 722E
    "UHAKOtE
    w3MK;<&.	A852°
    **	"--“HAMDWHEEL-C225I
    BRACKET-B 14 4 2 76—--1
    j-eouilibrator
    -O-r	30928
    HANOSPIKEn	O /T'FXlv til \	1.
    1	;
    ■•; J*. -'***’"’’W jB
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    H '■	\
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    RA PD 4831'
    Figure 14.—75-mm gun carriage M2- -left elevation.
    119
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    SCREW-AI56909-J
    Rz	NUT-BBDXIE-K	I	FITTING-CLDXIA
    DRAWBAR-D3I673’	BUSHING-AI56847 \	''.BUSHING-AI56845
    t	jiR LOCK, DRAWBAR,/\\ • PSk'Z R
    \\	SR?/I. ASSEMBLY-^X^ XR ^REARING-D31096
    V\	/ ]\P3^RTRZZx''^ REARING-BI4420I
    \ Xx / ./1 /S/JTl	/	( '	--r' 0	/
    RRljl	I (jff ?	BRACKET-BI44200
    TRAIL. RIGHT \ J 7fl	^R	R	T	TRAIL. LEFT
    \ILr|]	RN0B-BI4428I' \J | ~~TV	I | zRR
    FITTING-CLDXIA-RgJ_ F J/z=
    II rZ/	11 rTF^R/a xxR+ P YPIN-AI57I32
    RRlI	BUSHING-AI56846 R~4"---R-S U.>R-—
    PIN-AI57I34-. __IJ- 'HR H00K-BI444I0—R1 I I I fe^XX^X'' --PIN~Al57133
    PIN-BFAXIDF-'^ I ^R	Lj ElZZJlJ—W ~ PIN-BFCXIDE
    CONNECTION-AI57I3IR' i	_\V |ftv. HANDLE-C62484
    X-R	R X n ' RTR STRAP-QBDXIBC
    NUT-BBDX2C-^" RRRj'	I ____H BRACKET-BI444II
    L00P-BI44409	R----/— U RA FSD 641
    Figure 15.—Trail and spades
    120
    TM 9-1305
    GUN AND CARRIAGE, 7 5-MM, Ml 897	82
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    r n	h M
    1	_______________y/ (©)\
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    A '-Y0KE-C6I7I7	A0KE-C617I8 GJ	--jpJ -y XoUPLER- C6I533
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    Cl	_)	/+~\\ ---VALVE-C68995
    | I______________I |	L-PIN-BFAXIDG	A. (	) "---KEY-AI37933
    Y0KE-C6I719- ARC’ ELEVATING-D665
    fSTOP- BI06995
    / /L A \J) f Yrt CYLINDER-D30700	// y SCREW-BCKXIFK
    0	0	0	IlWASHER-BECXIM	-J L du\aii-k
    \\	JJ /)	[SCREW-BCBXIED
    X+A7 Z"^A AAa+TZ-----TURNBUCKLE-AI5733
    X	(___	\	7	I (fl-SPRING-AI564I
    I J  -----_Hr—-WASHER-AI5642
    1	PIN-BFAXIRD
    H--" AC—NUT-BBFXIA
    NUT-BBGX2C—T_rf	/-,	mJ	F O-HANDLE- BI44502
    PIN-BFAXCK-g jFR	44	<'-':
    WASHER BEBX2K —4 /	'	[ xz --PIN-BI43748
    a T~^	BIG0/-4B	RA FSD 2|9Q
    VIEW A-A
    Figure 16.—Mechanism, recoil, 75-mm gun M2.
    QCPFM/	[SCREW-AI45697	SCREW-AI455321
    SCREW-BCKX2AD	nwiRE-BFWXIA	W|RE_BFWX,A
    121
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    r———END-AI5724I	r————PIN-BFDX2AK
    I I W--------12---------TEL. MT. T27EI [u/OVj
    //	~n\	/	\	CAP-BI070I3----------
    ' /	\ ‘	1/ Ml	SCREW-BCBX4BD------
    i~i-T j	| T--m	\	WIRE-BFWXIB------
    L—U	[	J U-----8	/~\\	—CRADLE-D30957
    i I Jx— bolt-ai42104 —iinfx^	______x I
    CFFiX Fwasher-becxim	I	-Q, hX '! KMX	\ //
    FC \ / I SCREW-BCBXIED	“	113 U D 'Ff '))
    J	.	X~X	PIN-BI43748--
    (	j /X''----------------KEY-AI37933
    7	ARC, ELEVATING-D6658-X- X—
    _	ST0P-BI06995 I_______
    SCREW-BCKXIFK	wu^vv<-
    X-X	RA PD 8379
    Figure 17.—Cradle and arc- elevating.
    122
    TM 9-1305
    GUN AND CARRIAGE, 7 5-MM, Ml 89 7	82
    ------If0, F—7 ' r  -------------------- --------------------1-------------------
    RETAINER -BI43600------- ,M-------R—~L-»?/, I .	j-----v-J----
    X	I-------— CUP-AI56945
    PLATE - BI44266-------------
    //// ./	\\\\ I----------------BALL-AI56944
    PLATE-BI44267---------/////	\ vX\
    gTW'ZZZ.i  iwzX-dn	SPACER-AI56943
    RETAINER-8144268-------	177777?^ SCREW-BCKXIFU
    Hf Z I'	n
    / '	HT'z--Hl--------- SCREW-AI73734
    I	__। I | '/ ®
    SCREW -AI73729---------------. . Lgf	| '
    SCREW-BCTXIBF----------------Wj#! ) R ( I
    STUD-AI4I476 --—--------------1
    WASHER - BE AX3G------------—'•'"WEpR ( f- )
    NUT -BBBX2B-------------------" x
    fTR—H~Fk
    U4Z-^J	LA—n	RA FSD 2201
    Figure 18.—Trunnions.
    123
    9-1305
    82
    ORDNANCE DEPARTMENT
    TM
    [I______ j- SCREW - BCBX5B	----
    "'\Zl WASHER - BECXIG X®
    /	COVER-AI3799I /	\
    / z z<\	/	A
    FITTING - CLDXIA --L	' ' z/y \ Z ■
    PIN-BFDX5R -■	\	___\	/
    G ASKET- Al 37992	W^Z\	/
    SCREW - BCUXIFG Xz \	F FITTING ' CLDXIA
    SCREW - BCBXICD q Z\ 'x7^/J 7Z /	r SCREW-AI3804I
    N U T - B B B XIC	P ^Z X.
    WASHER - BECXIK ~ SCREW-BCDX2CC-1T GLAND-AI3803I Z	MS)
    NUT-BBAXIC 7	SCREW - BCUX1FG Z	\Z J
    WASHER - BECXIK -	^ZZZZZZZZZ=T:2ZZj
    /WASHER-AI36639 -	'	L SCREW - AI8498
    KEY-BGBXI —1	X. RETAIN ER-BI06970
    W0RM-AI37879 —	---BEARING - CADXIAD
    RA RD 7341
    Figure 19.—Elevating mechanism.
    124
    TM 9-1305
    82
    GUN AND CARRIAGE,
    7 5-MM, Ml 8 97
    X	FITTING-cldx i a
    K\	FGLAND-AI44539
    |\ P >ij "	[SCREW-BCUXIFG
    z'-zz	l xi\nj/i
    FC jv	r ? -Sswr r™/
    \	/ '.piL / i—n
    / f \ yen r' ' =C=-_1__________i____,	------tzX-HXt??
    X	/ :	II I \\	bearing, roller-caaxicn
    -SECTION A-A	XX	/ ;	jl • V ------WASHER-AI4370I
    NUT-BBRXIA’E I i y/	/ ' i| ' ; V-----PINION-BI42227
    PLUG. EXPANSION-BEDXIAZ_/ feUhWH-------------------------WASBER-A,43700
    I   —-ZZ(_    	______ / p O J I	y	BEARING, R0LLER-AI43826 -
    BEARING, BALL-CAAXIAE-{~R| nSpUtgL, j n	_____[RETAINER-AI43703
    GEAR-BI07062-------I	j —	[SCREW-BCUXIFG
    CASE, GEAR - C58657----, y	*Xj	’	--WHEEL, WORM - BI4I439
    BEARING, BALL-CAAXIAK-J '■ X	I K-k—— 1.___[NUT -AI438I0
    RETAINER-AI380271	GEAR[s_CREW-BCFX2AF
    SCREW-BCUXIFG | “	I	QLAND AI57035	[COVER-AI44538
    GLAND-AI380I8—------------------ 0LL0WER-AI57036	--------GASKET-AI44537
    HANDWHEEL-C225I-PACKING-AI57037	[SCREW-BCKX2AE
    NUT-BBFXIE71	___[SCREW-BCUXIFG
    PIN -BFAXICRJ	^Z"	' --WASHER“AI380I9
    -tp---KEY-AI38046
    RA FSD 2202
    Bigure 20.—Elevating mechanism—sectioned views.
    1.25
    TM 9-1305
    82	ORDNANCE DEPARTMENT
    n [SCR EW- BCBXICD
    -----QOVER^4I59I	\VwASHER-BECXIK -----WHEEL-6109248	S'LPtXoXo	’ -----IwSHERBBECXIG	x—PLUNGER-AI4I592\\ MAJHER,?.ELCX G /	KN0B-AI4I655		\\
    1X^^-P'n-bpaxIDkzM^spr1ng a141626	iW? ---------------
    . 1 ..... I	-----
    \ L	IX। QJ / n
    XIaM M !! H •[	1^Tr+jSWv
    MZX— :rXs=_==M	z“
    ]_[__/-----------------------.|	/ [SCREW-BCDX2CC
    VEzX—/ZX	I	/ MWASher-becxik
    RACK-C59949—///	\\	I	I	NUT-BBAXIC
    L COve R-AI4I590	\	i HANDWHEEL-C225l->
    ____PINI0N-BI09246 \ \\	//	j |	NUT-BBFXIE ____[SCREW-BCBX5B \ \\	//	|	PIN-BFAXICR--------- [WASHER-BECX1G	;	KEY-AI38046----
    -------RETAINER-AI4I589 ( -------SPACER-AI4I588	\------] -------BE ARING-CA AXIAL \---1—~ZZ^.7ZEZ:=	7
    j /	RA PD 634
    Figure 21.—Traversing mechanism.
    126
    TM 9-1305
    82
    GUN AND CARRIAGE, 75-MM, Al 18 97
    SCREW-AI38041	-------PIN-BFDX5.IL
    r— WORM- BI09247	[SCREW BCBXIEE
    r—RETAINER-BI06970	//// ^7/ l/TTTr^ WASHER-BECXIM
    rBEARING’CADXIAD	II /// t' IAhf] NUT-BBBXIE
    rSCREW-AI8498	,y// ! U ij.jJfjj/	- '""d-F-----
    -----------Fxt	"F—i
    | 111-—ffiOXX©»©J \M>	i I
    if----------nF----------	j) i
    ---FFF —H-J0INT.FLEXIBLE-AI38006	X	F XXNGCLDX^=^^^,xhi^^^^dxLPIN’BFAXIDK I F.	F
    SCREW-BCUXIFG--1	X
    WASHER-AI36639- |A \ \	F	-
    GLAND-AI38O3I-- LA-^F-LL______JX FFtFL __________J______. i \\	/
    SCREW-BODXIBD	.	1	“ =S^	2
    WASHER-BEAX2B	F'VxF	X IIV A//FxCTXl
    NUT-BBAXIE ------/fl i
    SCREW-BCFX2EF----(L---WF XF. ----------PIN-BFDX2CC	XFu/1 /
    ST0P-AI4I605-----ZFZF 7^	BUSHING-AI5670I-
    I [SCREW~BCBXIEC	l/l /I
    n	XFasher’becxim / 7
    c^F-i	HOUSING-6109226- W / /
    ' -..	। 1 y
    RA FSD 2203
    Figure 22.—Traversing mechanism—sectioned views.
    127
    TM 9-1305
    82
    ORDN ANCE DEPART M ENT
    NUT-AI37I49
    SCREW-BCNX2AC -L0CK-A3552
    PIN-AI4I45I -END-BI43540
    CYLINDER-B143542
    PIN- BFDX5F
    R0D-AI55908
    SPRING-AI55906
    END-BI4354I---
    CYLINDER-8143543
    RA PD 638
    Figure 23.-—Equilibrator assembly.
    128
    TM 9-1305
    82
    GUN AND CARRIAGE, 75-MM, Ml 897
    <0 o CM CM
    O
    axle---------------1; j :(
    SHIM-AI30442------------11--------------------------------“---------------RATCHET-AI304I7*
    BEARING-AI304II-------- -------T--J	---------'--------—SPINDLE - C45203
    BRACKET,LEFT-E281 I	j !'■ fto	(	---------STUD-BI28738
    BRACKET,RIGHT-E282 |	H'. I ;: | /frntTK,	CP^Tl-----)--(---------PIN-BFAX2AM
    *	SCREW-BCBXICG~1	J+g—1-—F,' / |/|; j	| J	\ -NUT-BBHX2B
    ★_________________________NUT-BBBXIC ______________Y j i |	;	-*4^/ U'~~'!V7 • ^Tl-"-WASHER-AI304I3
    *	WASHER-BECXIK_J	f~| | M	1 I I _Zj L-to	—NUT-BBFX2E
    FITTING-CLDXIA-----------7	; i ((	))	■;_	;| f 11 jjftoX-----PIN-BFAXIDL
    I I ; I ---------7	| :'H i I	PSCREW-BCBXIED
    -tF ,	I'F'lH |l""li''	NUT-BBBXIE
    BEARING-AI304I2---1 ji ■ --------------------- [	f —■	.WASHER-BECXIM
    TIRE-AI37854A“lj^_^^^^^ 1,1________—PACKING-AI30452
    TUBE-AI37854BJ	'p to, I;	p------- --------b>Jj DRUM-C62525
    WHEEL,DISK AND RIM--'■	I;	______feCzni______to FSCREW-BCBXIDD
    ASSEMBLY	pl il ■; ;	— NUT-BBBXID
    SHIM-AI30443--------1RT~--------------------------------_WASHER-BECXIL
    PIN-BFAX2BH	(U---j j —j—£>)	/K I	—BEARING - AI5722 3
    RING-C62653-----3^.	------HUB-C62505
    BEARING-AI57220to^+^^----------------------------Kfc-	-----NUT-BBBX2C
    W A S H E R - A13 0414----- |A	---BEA RING-AI5722O
    NUT-BBFX3A------------------------\ \	— STUD-BI44357
    CAP-BI44454------------------------—----------- --------------------------NUT-AI57225
    PIN-BFAX2AM	------------——CREW-BCNX2ce
    GASKET- BI44356----------------------—-------------------- [WASHER-BECXIG
    * used on left side only 1'IGURE -4- Brake and axle bracket, R. H., group assembly—75-mm gun carriage M1897A4.
    449370°—42---9
    129
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    130
    BUSHING-AI59325-1 SPACER-AI59434-	I X.	J )
    SHAFT-BI5O693 I FITTING'CLDXIB- fNUT-BBBXIC	I |	/
    CAM-BI44968_| NIPPLE-AI30664---	।-------SCREW-BCBXICF	/
    ■LEVER-064752 BRAKE-064675---- A—। WASHER'BECXIK	q	f
    SPINDLE-062266—1 fRX-----j—RACK-BI50685	]______
    //] \  I	r|— WASHER-BEBXIU
    |	f—t/_l!	_£ m r A i	l[NUT-BBFX3A /	~^T\X
    \ tjffl W n LAin~bfax2ac // (\	/) ^\\
    \	LKLiy Tr-X—‘T-U-X	1	/ /	-------------- \ \"N
    iMiw—T	-EJ 4—iS-4------------044-------1-0----©J------\AL
    qwy nWX T r > ■ SECTION A-A	ffM  J	/ AX /
    SCREW-BCBXIED]	f X >/	/ /
    NUT-BBBXIE -I	/ / /
    WASHER-BEOXIm]	\	/ X ,/ X
    SCREW-AI573641	\	I / /' /
    NUT-BBBXIE-*	/ /	RA FSD 2207
    washer-beoximJ
    Figure 25.—Brake and axle.
    TM 9-1305
    GUN AND CARRIAGE, 7 5-MM, Ml 8 97	82
    Oi
    - PIN,COTTER~BFAXIDP
    -ROLLER -BI44955
    -PIN-BI44962
    - SPRING- BI44957
    -SHOE, BRAKE-C62667
    _[PLATE,HOUSING BRAKE-
    [£62668
    RA PD 8377
    Figure 26.—Brake assembly.
    131
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    r	rV7 r
    ? F Z~/l (o) |XZ—------------ >
    / / /	7
    w	w v-GLASSES,MASTER PRESSURE GAGE (SPARE) AI7I5j
    | GASKET, OIL RESERVOIR (SPARE) 24-15-IOL^ X.	/
    ADAPTERS 24-15-100^	1	X	\	\
    j|B	*^Pf	Z. / X. /
    O-^ADAPTER 24-I5-I0D	RA po 4Q65	X^_.X j
    • .... .................................................................
    Figure 35.—Tools and spare parts for testing and repairing pressure gage M1923.
    140
    TM 9-1305
    GUN AND CARRIAGE, 7 5-MM, Ml 89 7	82
    141
    WRENCH, CLAMP (ELEVATING NUT COLLAR)-LHI9F
    r-FlLE, BREECH THREAD- 8907
    2	.......-...-...n
    rORILL, TWIST 4 MM rREAMER, TAPER, NO. 2 I
    L 24-I0-LHI9D	U-24-10-LH24H
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    REAMER,' TAPER, NoTjT^ REAMER, TAPErTnoTTg 24-I0-LH24G24-10~ LH24F
    7	... 9
    COUNTERBORE, 4MM ,/««**■	«	-------1
    24'10" LHI9G /JIG, ELEVATING NUT COLLAR 24-10-19-1 ^SCREWDRIVER, OILER NOZZLE - AI77I7
    ( }=———  ................................■■■---■■ ■■■^
    V 7	i0 >GAG€,CLEARENCE-86569
    GAGE FORCING CONE-24-40-7
    -	SB 11 UBUm
    jS^xiaunir -	•	I
    rSIGHT, B0RE,8REECH	rt XTRACTOR , SWEEPER ||
    V-I5-2A-II-RFHHA	\ L PLATE-24-IQ-LH35H
    X) r^l j 1.5	14	1 15
    SIGHT, BORE MUZZLE -A .	*
    15-2A-II-’~~	/
    GUN, OIL, 11 -IN. DIAM. CYL., 4-OZ.-CL BX IBZ
    RA PD 4966
    Figure 36.—Tools used for inspection and maintenance of gun and elevating nut collar.
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    ]	/XxRlZx	rf~Z
    =■	/ZZ^^Z^z^^^ZXXX	c ।
    f	=	/ //XZ/W	I ZWyXX \\ \	’
    f, J» 1€®\ ;
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    L_--^=Xi!!S=XS=^ 11
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    ‘	WRENCH, SCREW, MONKEY, KNF-HOL., 8-TKAXI6, >
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    CtOOL,HUB UNER DRIVING - 15 -5 "U8IE
    "“i * ''	' -	s	' '
    RA PD 4968
    Figure 39.—Tools used for maintenance of carriage.
    GUN AND CARRIAGE, 75-MM, Ml 897
    TM 9-1305
    82
    449370°—42---10
    145
    CLAMP, AXLE SLEEVE-2 4-IO-I7v
    <	o	o	o.	> <	z x	T	¥■
    W	til	1J	I 1	fl	i 1	fl	feB	F	1	f IB
    Z>L	I /
    WASHER, TEST, LEFT TRAVERSING NUT THRUST, SET	f
    24-10-23	I 3	4 j.|’j?®
    2	X_
    w	fir w U tf Wr it J v/fl )J M rWRENCH»AXLE dust
    XMWl1^^flllllilLllinmL	M. -.^v' X'	■")washer gland
    •	Hi L24-IO-LH3OB
    WASHER, TEST, RIGHT TRAVERSING NUT THRUST, SET 24-10-23	. “
    5	SLEEVE, AXLE MOUNTING-24-10-17BCy
    !	!	11	!	H	II ! ® e	ffjz
    I	»	a a	«	h	liiii	■*■	s
    G66E, THICKNESS, SET-24-I0-Z6	'	RA PO 4969
    Figure 40.—Tools used on axle and traversing mechanism.
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    5
    "■.........................*	*	...... u
    ^JjgsSSaiM*	.—-MsJ*-’■“*’
    1 2 '
    _________ »g—-y«~—~-. ,	gsagg
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    ...	.. sssm»2s^»	i»as£zsa'.	^aaS*””^	®®S®SW> 3.4	5	5	"?	8
    .........  ,...................	...... • ■ .	■-•-.<	>;N A ■.*'-—* —— ■ ,■ .   ................................... .mil ^ggs	ffiES^SBSS*	wssssks®
    tsSS^KKKS	!Wswm^sMOW«	...mu
    fflya^rrTMaggjgjgg, 8^^^RBSBS^^anaws!*^	■•raMMum%MMM»«•■ ''	4z-7<
    DIE, ART.,7 X IMM-A5320-X DIE, ART., 8 X IMM “A53l9r
    X^DJE, ART.,3 X .5MM-A5329 pDiE, ART., 5 X IMM ™A5327	/
    a © '■ ©x w @
    DIE,ART,4 X -5MM-A53281	DIE,ART,6 X IMM“A5326^	DIE, ART, 10 X I.5MM-A53I8 J
    ^DIE.ART., 12 X L5MM-A53I7 ^/-DlE, ART, 14 X 2MM~A53I6	DIE, ART, 8.6 X IMM~A532I-|
    ---DIE,ART.,16 X 2MM-A53I5
    zjtx ^.yy	'wy	ra po 4 97i
    Figure 42.—Dies and stocks.
    147
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    Figure 43.—Arrangement of contents in sight testing tool chest.
    148
    RA PD 4972
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 8 97	82
    11'	.*
    '	2 I I! 3 III
    I Ji jA
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    SEAT,TESTING, SIGHT	Bl	■II
    24*10 *10	| |	HI	,
    SIGHT, MASTER - 01281
    R A PD	4973
    REST,MASTER LEVEL" C339
    Figure 44.—Tools used in testing and adjusting sights.
    149
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    150
    O O	rGUIDE, SCRIBING, ANGLE OF SITE INDEX* '
    V y	\y24-IO- LH2 78	|_____
    j | I \	LEVEL «ASTER-24-IO-2-Tt’^ii^^S^l|
    i*i A	a	« rc
    'GLASS, MAGNIFYING ’ 24-IO" LH27F	/
    A-GUIDE, SCRIBING, DEFLECTION DRUM INDEX* y*24*IO-LH27A
    SCRI BER~24 " I 0'LH27E	fSEAT> TESTING, AUXILIARY LEVEL, llo-27’- 32"
    /	'	‘	//t(FOR SIGHTS OF FRENCH M A NUFACT URE)’C 2834
    'Z	SHIELD, PROTECTION" 24* IO*LH27DX
    ।	1	6 V	(	\
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    I	.	t(FOR SIGHTS OF AMERICAN MANUFACTURE)* C2835
    I	RA pq 4974
    Figure 45.—Tools used in testing and adjusting sights.
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	82
    Figure 46.—Tool for dismounting cradle right rear side plate (not issued).
    151
    RA PD 4975
    TM 9-1305
    82
    ORDNANCE DEPARTMENT
    ...............WX	U /	.
    WRENCH, OIL INDEX FOLLOWER	\ s'
    A7488	E>^|
    __________________,	g	-------cr
    <1 =>	|
    UAKini r-	____BPULLER,GEAR DEPTH GAGE-C58358
    HANDLE	----\
    A6788	-
    //	9	WRENCH,PISTON ROD NUT, FRONT
    ( FFx //	A8765
    WRENCH , PINTLE 6 TRAIL	GAGE FOR
    Bl 08514	STUFFINGBOX	WRENCH, STUFFING BOX HEAD
    THREADS	AND F0LL0WER-A8I6I
    AI36420
    RA PD 4827
    Figure 47.—Inspection and repair tools used on gun carriages.
    152
    TM 9-1305
    GUN AND CARRIAGE, 75-MM, Ml 897	82
    1	37 MM. GUN	I
    IaJ ~	O	I	_	<0
    - “ -
    *,
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    „_________14.499______3
    75 MM. GUN CARR, M2AI.M2A2 AND M2A3
    _____________________26____________________I
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    . 9.496.
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    SET, SQUARE END-AI7007\	/SET,THUMB N0TCH-A6803
    ,2 BMIO S " CZZXZX) rA po 4830
    Figure 49.—Tools for assembling ammunition chest connecting pieces.
    154
    TM 9-1305
    GUN AND CARRIAGE, 7 5-MM, Ml 89 7
    Appendix
    LIST OF REFERENCES »»
    1.	Standard Nomenclature Lists.
    a. Cleaning, preserving and lubricating materials__SNL K-l
    Z>. Gun materiel.
    Caissons and limbers_________________________SNL C-5
    Cart, artillery, M1918, and M1918A1, and reel, artillery M1909M1____________________________SNL C-ll
    Gun and carriage, 75-mm, M1897M1 and
    M1897M1A2___________________________________ SNL	0-4
    Gun and carriage, 75-mm, M2A1, M2A2 and
    M2A3________________________________________  SNL	C-12
    Gun and carriage, 75-mm, M1897A4_______________SNL	C-25
    Reel, battery M1917____________________________SNL	C-10
    Tools, special repair__________________________SNL	C-18
    c. Current Standard Nomenclature Lists are as tabulated here. An up-to-date list of SNL’s is maintained as the “Ordnance Publications for Supply Index”_________ (OPSI)
    2.	Explanatory publications.
    a.	Ammunition, general_____________________________TM 9-1900
    b.	Cleaning, preserving and lubricating materials__TM 9-850
    c.	Fire control.
    Ordnance maintenance, circles, aiming, Ml918
    (French), M1916, M1916M1___________________TM 9-1530
    Ordnance maintenance, sight, M1901 (French)__TM 9-1550
    Ordnance maintenance, mount, telescope, M22__TM 9-1552
    Ordnance maintenance, telescope, battery com-
    mander’s, M1915, M1915A1___________________TM 9-1580
    Ordnance maintenance, finders, range, 1 meter base and 80-cm base, all types_______________TM 9-1585
    Ordnance maintenance, setters, fuze, bracket, M1916 and setters, fuze, hand, M1912 and M1913________________________________________ TM 9-1590
    Ordnance maintenance, compass, prismatic, M1918________________________________________TM 9-1595
    •
    155
    TM 9-1305
    ORDNANCE DEPARTMENT
    d.	75-mm gun materiel__________________ TM 9-305
    e.	Maintenance.
    Electric and oxyacetylene welding- OFSB 5-2
    Maintenance of materiel in hands of troops_______________________ OFSB 4—1
    Ordnance maintenance proce-dure—materiel, inspection and repair__________________________ TM 9-1100
    Star-gaging equipment and guttapercha impressions______________ TM 9-1860
    f.	Miscellaneous.
    Artillery gun book_______________ O. O. Form 5825
    Ordnance proof manual (proof of guns and carriages)
    g.	Ordnance drawings.
    75-mm gun M1897__________________ Class 52. Div. 85
    75-mm gun M1897A2________________ Class 52, Div. 221
    75-mm gun M1897A3________________ D30033
    75-mm gun M1897A4.1______________ D33000
    75-mm gun carriages M1897M1A2 and M1897A4_____________________ Class 2, Div. 94
    Class 2, Div. 97
    Class 2, Div. 262
    Equipment and special repair Class 2, Div. 301 tools-------------/.------------ Class 27, Div. 22
    156
    TM 9-1305
    INDEX
    Adapter, high speed, for gun carriage M1897A4:	Paragraph Page
    Description----------------------------------------------- 12	20
    Inspection_____________________________________________r__	17	31
    Angle of site mechanism, maintenance and repair of gun carriages
    M1897, M1897MIA2, and M1897A4_____________________________ 30	62
    Brake mechanism, maintenance and repair of carriage M1897MIA2________________________________________________________ 32	64
    Breech mechanism, description_____________________________________ 8	6
    Carriage, gun:
    Description of M1897 and M1897MIA2___________________________ 11	11
    Description of M2A1 and M2A2_________________________________ 13	23
    Inspection of M1897, M1897MIA2, and M1897A4__________________ 16	30
    Inspection of M2A1, M2A2, and M2A3___________________________ 18	31
    Maintenance and repair of M1897A4____________________________ 33	67
    Maintenance and repair of M2A1, M2A2, and	M2A3________  34	67
    Roller path clearance on M1897, M1897MIA2, and M1897A4__	21	40
    Coupler, piston rod, description_________________________________ 10	11
    Data:
    Artillery gun book (O. O. Form 5825)__________________________ 3	2
    Average life of gun________________‘______________________ 4	2
    General______1____________________________________________ 2	2
    Reference to other Technical Manuals______________________ 5	3
    Elevating mechanism, maintenance and repair of carriages
    M1897, M1897MIA2, and M1897A4______________________________ 28	56
    Firing mechanism, description_____________________________________ 9	9
    Gun:
    Description of M1897__________________________________________ 6	3
    Description of M1897A3, M1897A4, and	M1897A2________________ 7	6
    Inspection of M1897 mounted on gun carriages M1897,
    M1897MIA2. and M1897A4__________________________________   14	26
    Inspection of M1897A2, M1897A3, and M1897A4 mounted on
    gun carriages M2A1, M2A2, and M2A3________________________ 15	30
    Maintenance and repair of M1897______________________________ 24	46
    Maintenance and repair of M1897A2, M1897A3,	and M1897A4-	25	50
    Inspection and repair of special tools___________________________ 81	104
    Level test, master_______________________________________________ 36	70
    Range scales, maintenance and repair of carriages M1897,
    M1897MIA2, and M1897A4________________________________________ 28	56
    Recoil mechanism:
    Inspection___________________________________________________ 20	33
    Maintenance and repair of M1897 and	modifications_________	26	50
    Maintenance and repair of M2_________________________________ 27	55
    Modifications________________________________________________ 19	32
    Nitrogen pressure and floating piston friction on gun car-
    riages M2A1, M2A2,	and M2A3_____________________________ 22	41
    Roller path clearance on carriages M1897, M1897MIA2, and M1897A4_______________________________________________________   21	40
    157
    TM 9-1305
    INDEX
    Paragraph Page
    Shield, maintenance and repair of carriage M1897MIA2_______ 32	64
    Sight bracket adjustment___________________________________ 46	78
    Sight differences between French and American manufacture of
    the M1897, M1897MIA2, and M1897A4'gun carriages_____________ 35	69
    Sight tests:
    Angle of site level test__________________________________ 42	75
    Auxiliary angle of site level	test______________________   43	75
    Battery sight for deflection______________________________ 41	74
    Battery sight for elevation_______________________________ 40	73
    Line sights----------------------------------------------- 37	70
    Sight_____________________________________________________ 39	72
    Sight bracket for elevation------------------------------- 45	76
    Sight bracket for lost motion	of	the deflection drum----- 44	75
    Summary__________________________________________________  48	83
    Table of examples_________________________________________ 47	82
    Special field artillery vehicles:
    Inspection________________________________________________ 23	42
    Maintenance and repair____________________________________ 49	85
    Tools for inspection------------------------------------------ 50	95
    Tools for maintenance and repair___________________________ 51-80	99
    Trails, maintenance and repair, M1897, M1897MIA2, and
    M1897A4____________________________________________________  29	59
    Traversing mechanism, maintenance and repair-,.--------------- 31	63
    Trunnion friction test----------1-------------------------- 38	71
    Wheels, maintenance and repair of carriage	M1897MIA2__________ 32	64
    Work orders, field service modification----------------------- 82	105
    [A. G. 062.11 (8-16-41).]
    By order of the Secretary of War:
    G. C. MARSHALL,
    Chief of Staff.
    Official :
    J. A. ULTO,
    Major General,
    The Adjutant General.
    Distribution :
    D (2); IBn 9 (2); IC 9 (4).
    (For explanation of symbols see FM 21-6.)
    158
    U. S. GOVERNMENT PRINTING OFFICE: 1942
    For sale by the Superintendent of Documents, Washington, D. C.
    p m
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