    [Direct-Fire Telescopes for 3-Inch and 90-MM Antiaircraft Guns]
    [From the U.S. Government Publishing Office, www.gpo.gov]

    ﻿
    TM 9-1600
    Wh3£*.9-ieo6
    WAR DEPARTMENT
    TECHNICAL MANUAL

    August 21, 1942
    Document Reserve
    ORDNANCE MAINTENANCE
    DIRECT-FIRE TELESCOPES FOR 3-INCH AND 90-MM ANTIAIRCRAFT GUNS
    NON-CIRCULATING
    NTSC' MSRARY
    TM 9-1600
    1-2
    TECHNICAL MANUAL No. 9-1600
    WAR DEPARTMENT, Washington, August 21,1942.
    ORDNANCE MAINTENANCE
    DIRECT-FIRE TELESCOPES FOR 3-INCH AND 90-MM ANTIAIRCRAFT GUNS
    Paragraphs
    Section I. General_________________________________________ 1-3
    II.	Description_________________________________  4-8
    III.	Care and preservation_______________________ 9-11
    IV.	Inspection__________________________________ 12-19
    V.	Maintenance and repair______________________20-22
    VI.	Disassembly and assembly____________________ 23-26
    VII.	Painting___________________________________ 27-28
    Page
    Appendix. List of references______________________________ 50
    Index_____________________ _______________________________ 51
    Section I
    GENERAL
    Paragraph
    Scope__________________________,___________________________________ 1
    Characteristics____________________________________________________ 2
    Differences in models---------------------------------------------- 3
    1. Scope.—This manual is published for the information and guidance of ordnance maintenance personnel. It contains detailed instructions for inspection, disassembly, assembly, maintenance, and repair of the telescope mounts M26, M27. M28, and M29, and elbow telescopes M24, M25, and M26, supplementary to those in the Field Manuals 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.
    Note.—Information as to assembling telescope mounts to the gun; preparation of materiel for use under unusual conditions; and packing, storage, and shipment, is not available now but will be included in a revision of the manual.
    2. Characteristics.—a. The telescope mounts and elbow telescopes discussed herein are used as direct fire sighting equipment on 3-inch and 90-mrn antiaircraft gun carriages. These carriages operate from a separate fire-control system for antiaircraft fire, and from direct-fire telescopes when used against ground and naval targets. These telescopes are used by the azimuth and elevation hand-
    474171°—42--1	1
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    2—3
    ORDNANCE MAINTENANCE
    wheel setters of the gun crew independently of the usual antiaircraft fire-control system.
    b. The sighting equipment for each gun consists of a telescope mount and elbow telescope for aiming the gun in azimuth, and a telescope mount and elbow telescope for aiming the gun in elevation. The elevation telescope reticle is graduated in yards range, and the azimuth telescope reticle is graduated in mils lead. In aiming the gun, the target image is held on the appropriate range and lead graduations.
    c. Application of these telescope mounts and elbow telescopes is as follows:
    (1) 3-inch antiaircraft gun mount M2A2.
    Telescope mount M261 Elbow telescope M24 ]
    azimuth
    elevation
    Telescope mount M27
    Elbow telescope M25
    (2) 90-mm antiaircraft gun mount Ml and Ml Al.
    Telescope mount M281 Elbow telescope M24 J “
    Telescope mount M291 Elbow telescope M26 J
    azimuth
    elevation
    3. Differences in models.—a. The several telescope mounts are shown in figures 1 to 4. The mounting brackets of these telescope mounts are differently shaped to fit the particular mounting surfaces on the gun. The M26 and M28 mounts (azimuth) are bolted onto the top carriage on the left side of the gun; whereas the M27 and M29 mounts (elevation) are bolted onto the right side of the gun cradle. The supporting bracket (fig. 15) is not used when the M28 mount is applied to 90-mm gun mounts Ml, equipped with data transmission systems M6 or T17. The M26 and M28 mounts also have an elevating mechanism that rotates the telescope holder in the elevation plane. This keeps the azimuth scale of the elbow telescope on the target when the target is above or below the level of the gun. Apart from these differences, the telescope mounts are similar in design and construction.
    b. The elbow telescopes M24, M25, and M26 (fig. 5) are identical except for the reticle pattern. Reticle patterns for these telescopes are shown m figure 6. Elbow telescope M24 (azimuth) uses the reticle with the horizontal mil scale. Elbow telescopes M25 and M26 (elevation) use reticles which arc marked to indicate ranges in
    2
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    DIRECT-FIRE TELESCOPES
    yards for specific ammunition, as indicated by the legend engraved on the reticle.
    -*** .....
    ****	~ y
    LATERAL ADJUSTMENT	*	C WMtMl >
    CLAMPING SCREWS—v-
    WORM	V ’	|...	"
    X. :"AWfck:'- T' ''W”W •«
    ■ nt® <' . i I 3k 4 " jjp®
    ’•jSjjEL ' ■' f l-~
    - ^IeL- WJIf ~5
    -W;-'
    w r '? i
    4^“ ?.W' "	itf
    CLAMP—i
    * *{
    -	^^saigggjj^^^ ’"y RETICLE ROTATION
    HP	WORM
    । -	/ '“" ' f^‘' f\ —CLAMPING SCREW
    wjp' I
    1*’^ I
    wT	. U-'x
    y ELEVATION KNOB-> IK- O '’''■ "' "'
    L-wing NUT
    RA PD 7055
    Figure 1.—Telescope mount M26.
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    3
    ORDNANCE MAINTENANCE
    ELEVATION ADJUSTMENT
    CLAMPING SCREW----
    WORM------
    RETICLE ROTATION
    WORM
    SCREW
    Figure 2.—Telescope mount M27 with elbow telescope M25.
    RA PD 7056
    LATERAL ADJUSTMENT
    SCREWS
    WORM
    4
    D1RECT-FTRE TELESCOPES
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    3
    5
    LATERAL ADJUSTMENT |
    CLAMPING SCREWS -r--•
    WOR M .
    RETICLE ROTATION
    WORM--------------x
    CLAMPING SCREW-x^^ x
    ■	»\ \
    ELBOW TELESCOPE,M24~^
    ELEVATION KNOB---------
    ' < rA PD4666
    Figure 3. -Telescope mount M28 with elbow telescope M24.
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    ordnance maintenance
    RETICLE ROTATION	ELEVATION ADJUSTMENT
    WORM-------------|	r-WORM
    CLAMPING SCREW-1	I	'	CLAMPING	SCREW
    •	*	*
    ■ Js
    ।	L-j-elescope CLAMP	/	R
    L-ELBOW TELESCOPE,M26
    LATERAL ADJUSTMENT /	x	>
    CLAMPING SCREWS— '
    worm-----—-----/
    RA PD 4667
    Figure 4.—Telescope mount M29 with elbow telescope M26.
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    1) 1R E (!T-FI K E TEL ESCOPES
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    Figure 5.—Elbow telescopes M24, M25, M26.
    -NAME PLATE DATA
    I I
    |||	— EYE SHIELD
    Ilf
    /	RA PD 4668
    TM 9-1600
    3
    ORDNANCE maintenance
    8
    /s
    I I I • I 1 I ‘ I • I • t ■ I ■ I ■ t ■ I	-I—F   ~	r	.-- —J------
    5 < 3 2 1	' 2 3 4 ’	==5^=*!^^^ J| ^=^^=^2^=
    \\	// -1 \\ _===^^'i—	// Jj =---------------- //
    \	° \<	2 --------- 30-30 ---/
    \. ✓	4* y I \.	/ I \ # J
    3" APS’ F M62	>//	NN	90 MM. S, Ml, F M43
    1 50 MILS
    RA PD 7057
    M24‘	® m25.	@ M26.
    Figure 6.—Reticle patterns for elbow telescopes.
    DIRECT-FIRE TELESCOPES
    TM 9-1600
    4
    Section II
    DESCRIPTION
    Paragraph
    Telescope mount M26____________________________________________________'____ 4
    Telescope mount M27__________________________________________________________ 5
    Telescope mount M2S__________________________________________________________ 6
    Telescope mount M29__________________________________________________________ 7
    Elbow telescopes M24, M25, M26_______________________________________________ 8
    4.	Telescope mount M26.—a. The telescope mount M26 consists principally of the mounting bracket, spindle assembly, elevation worm housing, and telescope holder.
    b.	The mounting bracket (fig. 9, sec. E-E) bolts onto the left side of the top gun carriage and is the supporting element of the mount. It has two split clamping collars (fig. 9, sec. F-F) and a third solid collar (fig. 9, sec. G-G) which houses the lateral adjusting worm. The clamping collars lock the lateral adjustment setting against accidental rotation or backlash of the adjusting worm.
    c.	The spindle assembly (fig. 9, sec. E-E) consists of a spindle and gear pinned together to form an offset L as shown in figure 8, section A-A, and figure 9, section E-E. The spindle fits into the three collars on the mounting bracket. It is held by a shoulder on the spindle below the lower split clamping collar, and by a round nut (fig. 9, sec. E-E) on the upper end above the upper split clamping collar. Operation of the elevation worm rotates the elevation worm housing about its supporting gear (fig. 8, sec. A-A).
    d.	The elevation worm housing (fig. 8, sec. A-A) contains the elevation worm (fig. 8, sec. C-C) and supports the telescope holder assembly (fig. 8, sec. A-A, and fig. 10). The telescope holder is jotated by the reticle rotation worm (fig. 8, sec. B-B) and may be clamped in position by the clamping screw.
    e.	One end of the telescope holder (fig. 10) fits into a bearing surface in the elevation worm housing (fig. 8, sec. A-A) and is held in position by a plug. A clamp on the other end of the holder fits around the telescope body. When the telescope is placed in the telescope holder, a flat locating surface on the telescope body engages a similar surface on the holder so that when the clamp is tightened the telescope is held firmly.
    /. The schematic arrangement of the telescope mount is shown in figure 11. There are three axes of rotation: one through the spindle vertical axis, one through the horizontal axis perpendicular to the gun bore, and one through the telescope objective axis. The first two motions permit movement of the telescope in azimuth and elevation
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    4—5	ORDNANCE MAINTENANCE
    so that the line of sight can be directed parallel to the bore of the gun. The third motion permits rotation of the field of view with respect to the reticle pattern, thus bringing the horizontal reticle lines parallel to the horizon or other horizontal line in the field of view which is parallel to the horizontal reticle line.
    5. Telescope mount M27.—a. The telescope mount M27 consists principally of the mounting bracket, spindle assembly, elevation worm housing, and telescope holder.
    ~b. The mounting bracket (fig. 14, sec. D-D) fits onto the gear segment on the right gun trunnion. Mounted in this way, the telescope mount rotates in elevation as well as in azimuth with the gun. The bracket has two split clamping collars (fig. 14, sec. E-E) and a third solid collar (fig. 14, sec. F-F) which houses the lateral adjusting worm.
    c.	The spindle assembly (fig. 14, sec. D-D) consists of a spindle and gear pinned together to form an offset L as shown in figure 14, section D-D, and figure 13, section A-A. The spindle fits into the three collars on the mounting bracket. It is held by a shoulder on the spindle above the upper clamping collar, and by a round nut (fig. 14, sec. D-D) on its lower end below the lower collar. Operation of the elevation worm rotates the elevation worm housing about its supporting gear (fig. 13, sec. A-A).
    d.	The elevation worm housing (fig. 13, sec. A-A) contains the elevation worm and clamping screw, and supports the telescope holder assembly (fig. 13, sec. A—A, and fig. 10). A worm and clamping screw (fig. 13, sec. C-C) similar to the elevation worm and clamping screw are provided for rotating the telescope holder and clamping it in position.
    e.	One end of the telescope holder (fig. 10) fits into a bearing surface in the elevation worm housing (fig. 13, sec. A-A) and is held in position by a threaded plug. A clamp on the other end of the holder fits around the telescope body. When the telescope is placed in the bracket, a flat locating surface on the telescope engages a similar surface on the bracket so that when the clamp is tightened the telescope is held firmly.
    f.	The telescope mount M27 closely resembles the telescope mount M26. The schematic diagram shown in figure 11 applies to the telescope mount M27, with the following differences: The bracket is fastened to the right gun trunnion with the spindle in an inverted position. The elevation worm is not provided with a knob, but is arranged for screw driver adjustment.
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    11
    AA't'V
    ; i OS'/} eT
    O
    (jv/ mounting bracket	I H li
    r^Fz-Pn6
    \ ZZIZZZA	—CAP SCREW WITH NUT AND WASHER
    \	! 1,^7	Ft
    4S>	kSl
    *dSULO1S	.	^ ELEVATION KNOB	RA PD 24102
    Figure 7.—Telescope mount M26, assembled view.
    TM 9-1600
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    ORDNANCE MAINTENANCE
    H-------------PIN
    SPINDLE-
    E/f ~r/-——GEAR	rF^---------COLLAR
    ELEVATION WORM^	'y	__	----PIN
    p ,____ \	W0RM LXi^M^-RETICLE rotation WORM
    SCREW. WF------^HOUSING
    Mn-r^f^Lt	[RETICLE	tWJzOz °'L
    6 \ \ \	f1QN W0RM	11--CLAMPING SCREW
    TTT-—sc r e w	r~fl ~f~ j	:■ —f
    I* — PLUG	---WASH ER
    I	~~r
    I	/	1x1
    /	/	£ o
    /	/	5?
    Figure 11.—Telescope mount M26, schematic diagram.
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    ORDNANCE MAINTENANCE
    r ffiL —
    A*
    Jfrfrs
    Mfr •
    c D B
    ArSAElSiT a	fjjpSfr
    r_	tpArdfr
    ^---~1A	/pfr
    »rfl:'E13p*	O Cv ; 0
    —fo	MOUNTING h\* g——r/
    BRACKET \ T—*1- Jy
    £j: b—CAP SCREW WITH NUT AND WASHER
    XfrZD RA PD 24107
    Figure 12.—Telescope mount M2", assembled views.
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    PIN--CLAMPING BOLT ASSEMBLY
    TELESCOPE HOLDER ASSEMBLY-F71-If-4-]-n
    A--L—----TELESCOPE HOLDER-*' /	!	---CLAMP
    SCREW— >	________
    ROUND NUT—I Ar---------fN	' \	#7
    x-j <_ji i. . y	zy
    GEAR----	: I /	\	PIN-----
    __________________ ;	\	SECTION B-B
    k/z .	M rCOLLAR
    spin dleX/
    ■-aJa \	\A	k- ~ mWIj —PIN
    \ '/A r	RETICLE ROTATION WORM
    2pXT/t']	K y Sn	i
    ELEVATION WORM HOUSING—1	--NUT
    plug —1 lscrew Jr----------------i_---,ZjL
    RIVET—	LJr"7^^Woi
    NAME PLATE—*	CLAMPING SCREW—* *—WASHER
    SECTION A-A	SECTION C-C
    (THROUGH RETICLE ROTATION WORM. SECTION THROUGH
    ELEVATION WORM IS IDENTICAL)	RA PD 24108
    Figure 13.—Telescope mount M27, section views A—A to C—C.
    4741.71°—42----2
    TM 9-1600
    5	ORDNANCE MAINTENANCE
    ___	।—OIL CUP
    SPLIT CLAMPING COLLAR I	---WASHER
    /	! ta M	|	(PART OF MOUNTING p-ZZ'ZPpS_'
    J____I___	: j o |j	BRACKET)	J
    \ J/ '	'"I
    .7'	[ 114-CLAMPING SCREW
    LLJJ
    SECTION E-E
    ZJ______	--MOUNTING BRACKET
    TVT7 i A^Z	--------NUT
    VT------ ZZ	F------WASHER
    M----j-ZZ	।-SCREW
    SPINDLE ASSEMBLY--i <	pZ—y-l.
    j. i. □ -wzi z—p,n Z^M-——Zzz	--COLLAR
    LATERAL ADJUSTING WORM ____77]	i i	--lateral ADJUSTING WORM
    I j
    W	rSEW (SHOWN	C°LLAR
    ROUND NUT-Z4l-^===fnlZ^_ ik-KCVV ^huwin	1 (PART OF MOUNTING BRACKET)
    AH /ttLJ -j0UT OF POSITION) , >[	I-
    SECTION D-D	U" SECTION_F-F
    (THROUGH LATERAL ADJUSTING WORM) RA PD 24109
    Figure 14.—Telescope mount M27. section views D—D to F—F.
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    DIRECT-FIRE TELESCOPES
    6. Telescope mount M28.—a. The telescope mount M28 consists principally of the mounting bracket, spindle assembly, elevation worm housing, and telescope holder,
    b.	The mounting bracket (fig. 17, sec. E-E) bolts onto the left side of the top gun carriage above the azimuth handwheels, and rotates only in azimuth with the gun. The bracket has two split clamping collars (fig. 17, sec. F-F) and a third solid collar (fig. 17, sec. G-G) which contains the lateral adjusting worm. The supporting bracket (fig. 15) is not required with 90-mm gun mounts Ml, when equipped with data transmission systems MG or TT7.
    c.	The spindle assembly (fig. 17, sec. E-E) consists of a spindle and gear pinned together to form an offset L as shown in figure 16, section A-A, and figure 17. section E-E. The spindle fits into the three collars on the mounting bracket. It is held by a shoulder on the spindle below the lower clamping collar, and by a round nut on its upper end above the top collar. Operation of the elevation worm rotates the elevation worm housing about its supporting gear (fig. 16, sec. A-A).
    d.	The elevation worm housing (fig. 16, sec. A-A) contains the elevation worm (fig. 16, sec. C-C) and supports the telescope holder assembly (fig. 16, sec. A-A, and fig. 10). The telescope holder is rotated by the worm (fig. 16. sec. B-B) and may be clamped in position by the clamping screw.
    e.	One end of the telescope holder (fig. 10) fits into a bearing-surface in the elevation worm housing (fig. 16, sec. A-A) and is held in position by a plug. A clamp on the other end of the holder fits around the telescope body. When the telescope is placed in the bracket, a flat locating surface on the telescope body engages a similar surface on the bracket so that when the clamp is tightened the telescope is held firmly.
    /. The schematic arrangement of the telescope mount is similar to that shown in figure 11.
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    ORDNANCE MAINTENANCE
    20
    if "	!	©
    L	©	\
    —h I UAjOJU	0f( jj©
    \ 'v ©TT-c z /
    GREASE FITTING—1	SUPPORTING BRACKET-,	VX
    i (£bl !o "^1^7> rWASHER	CAP SCREW WIThI f
    “^S? Y	NUT AND WASHER [\	—>=-[-----
    p __j *	_______2 w?
    TIT. ill ,i - TT A	B	uT=±==V———
    'Ok/f	e nn—r ~i—rlh>Xn~R
    t 11 TOLJLJJ L MOUNTING RRACKFT
    flpXttk / '	O W J J gg
    p}	r!l .lir RA PD 241’°
    D	D
    Figure 15.—Telescope mount M28, assembled views.
    TM 9-1600
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    DIR ECT-FIRE TELESCOPES

    O—-- -Z3----------P,N
    SPINDLE------J	, J
    )	;	----GEAR	iTlZXaaTvI
    ELEVATION WORM--------------—-V ELEVATION WORM HOUSING Q MMEjl
    NUT______	-----Az-,	TELESCOPE HOLDER ASSEMBLY
    SCREW---	JiOlL
    —PLUGW	--CLAMPING SCRE
    ----------------Z.l. I------rivet	Lt2Z^T~iLJ nut
    — NAME plate	section b-b
    ZjT—J	(THROUGH RETICLE ROTATION WORM)
    *"	—''	------PIN
    SECTION A-A
    PLUNGER----	-- zj____________________________PIN
    SCREW--
    SPRING=jjjjj^\	CLAMP----fflWTELESC0PE H°LDER
    ELEVATION WORM---- —S-1	I 7
    BALL SOCKET-jBj >//
    SCREW---CLAMPING BOLT ASSEMBLY	--PIN
    BALL CAP--WASHER
    j[ -------ELEVATION KNOB	SECTION D-D
    SECTION C-C	RA PD 24
    Figure 16,—-Telescope mount -M28, section views A—A to D—D.
    21
    ____________SCREW (SHOWN 90° OUT OF POSITION)
    —HL_____ROUND NUT	z»r—----— CLAMPING SCREW
    gEF -XX _________lr	washer ]//______.x LATERAL ADJUSTING WORM	j|j7 '''W< /	NUT
    fr---MOUNTING BRACKET
    T WZW SHOWN 120° OUT OF POSITION)	-----SPLIT CLAMPING COLLAR
    I ’—(PART OF MOUNTING BRACKET) -----SPINDLE ASSEMBLY	^<<7 J----L------SECTION F-F
    r—0IL CUP
    )	/V\j------LATERAL ADJUSTING WORM
    k/jO ‘	—PIN
    Ffrwl /XWr —------------A— U C>WW
    \4	/	-----S0LID COLLAR
    (PART OF MOUNTING BRACKET)
    SECTION E-E	SECTION G-G
    (THROUGH LATERAL ADJUSTING WORM)	RA PD 24112
    Figure 17.—Telescope mount M28, section views E-E to G-G.
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    7. Telescope mount M29.—a. The telescope mount M29 consists principally of the mounting bracket, spindle assembly, elevation worm housing and telescope holder.
    b.	The mounting bracket (fig. 20, sec. D-D) bolts onto the right side of the gun cradle in front of the right trunnion. Mounted in this way, the telescope mount rotates in elevation and azimuth with the gun. The bracket has two split clamping collars (fig. 20. sec. E-E) and a third solid collar (fig. 20, sec. F-F) which houses the lateral adjusting worm.
    c.	The spindle assembly (fig. 20, sec. D-D) consists of a spindle and gear pinned together as shown in figure 20, section D-D, and figure 19, section A-A. The spindle fits into the three collars on the mounting bracket. It is held by a shoulder on the spindle above the upper clamping collar, and by a round nut onto its lower end below the lower collar. Operation of the elevation worm rotates the elevation worm housing about its supporting gear (fig. 19, sec. A-A). The gear is elongated to place the telescope in a convenient position for observation.
    cl. The elevation worm housing (fig. 19, sec. A-A) contains the elevation worm and clamping screw and supports the telescope holder assembly (fig. 19, sec. A-A, and fig. 10). A worm and clamping screw (fig. 19. sec. C-C) similar to the elevation worm and clamping screw rotate the telescope holder and damp it in position.
    e.	One end of the telescope holder (fig. 10) fits into a bearing surface in the elevation worm housing and is held in position by a plug (fig. 19, sec. A-A). A clamp on the other end of the holder fits around the telescope body. When the telescope is placed in the bracket, a fiat locating surface on the telescope engages a similar surface on the bracket so that when the clamp is tightened the telescope is held firmly.
    f.	Except for the shape of the mounting bracket and the relative length of the gear which supports the elevation worm housing, the telescope mount M29 closely resembles the telescope mount M27. The schematic diagram shown in figure 11 applies to the telescope mount M29, with the following differences: The bracket is fastened to the right side of the gun with the spindle in an inverted position. The elevation worm is not provided with a knob, but is arranged for screwdriver adjustment.
    23
    UX--------MA
    J| Jj	D ®
    Ci J,.----''“' ' L rt—i________~’	--'aCfe
    J A' , -	qpgy tHQz
    /#■ Sr '/ it"	/m
    /	.-MOUNTING BRACKET	/ q
    £}Z-j}	_ /^CAP SCREW WITH NUT AND WASHER
    '®_?7	© RA PD 24113
    Figure 18.—Telescope mount M29, assembled views.
    24
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    7	ORDNANCE MAINTENANCE
    DIRECT-FIRE TELESCOPES
    TM 9-1600
    7
    25
    TELESCOPE HOLDER ASSEMBLY	P'Njj|]	CLAMPING BOLT ASSEMBLY
    ELEVATION WORM HOUSING-.	N I ' I M	XX f \\\—CLAMP
    |||'-	TELESCOPE HOLDER-[___
    _____________________J?
    r c	pin^w/
    t ;	\	pin
    I	A	section	b-b
    VU'FTT l-GEAR
    W/L spindle	rm
    1-PIN	ELEVATION W0RMx \	T jf'J
    RETICLE ROTATION WORM-fr^^W^^Aj — SCREW PIN	___
    PLUG---	[	[	--NUT
    SECTION A-A	RIVETJ LNAME PLATE	WASHER
    --------- I 4	---CLAMPING SCREW
    COLLAR—p“b <
    RETICLE ROTATION WORM —=E n._	£ S J |
    SECTION C-C
    (THROUGH RETICLE ROTATION WORM. SECTION
    THROUGH ELEVATION WORM IS IDENTICAL)	RA PD 24114
    Figure 19.—Telescope mount M29, section views A-A to C-C.
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    ORDNANCE
    MAINTENANCE
    >>
    c c

    pNUT
    OIL CUP	SPINDLE ASSEMBLY	rr-?-’"I-----WASHER
    0^*5------------------- =— CLAMPING SCREW
    —----------------lj mxi
    LROUND NUT	SECTION E-E
    SCREW ,	Al [ . /
    (SHOWN 90° OUT OF POSITION)	(£D	T>'	p PIN
    I ~~ i	{//yA>WiW~C0LLAR
    J	|«T^—[LATERAL ADJUSTING
    MOUNTING BRACKET —	Z [WORM
    LATERAL ADJUSTING WORM /	M
    ROUND NUT -AftT.p' ICl z'	SECTION F-F
    SCREW (SHOWN 90° OUT OF POSITION)-^ T	(THROUGH LATERAL ADJUSTING WORM)
    SECTION D-D	RA PD 24115
    Figure 20.—Telescope mount M29. section views D- I> to F—F.
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    DIRECT-FIRE TELESCOPES
    8. Elbow telescopes M24, M25, M26.—a. These elbow telescopes are mechanically identical, differing only in the reticle patterns (fig. 6). Assembled and sect ioned views of the elbow telescope are shown in figure 21.
    b.	The telescope legs are approximately 3 and 3y2 inches long, respectively. The shorter leg has a cylindrical bearing surface and a flat locating surface to match the corresponding surfaces of the telescope holder. The longer leg, which houses the eyepiece portion of the telescope, carries a soft rubber eyeshield (fig. 21). The adapter to which the eyeshield is clipped can be disengaged from the groove in the telescope body and slid along the tube until the end of the shield is flush with the end of the tube.
    c.	The lenses and reticle are contained in cylindrical metal cells, and are retained in their respective cells by threaded rings and lock screws. The cells, in turn, are firmly secured in the telescope body in a manner which minimizes the possibility of parts working loose in service.
    d.	The Amici prism is secured in the elbow of the telescope body by a holder and wedge. The prism is protected by covers which screw into the sides of the telescope body as shown in figure 21, section A-A.
    e.	Optical characteristics of the telescope are as follows:
    Power________________— ------------------------------------------ 3X.
    Field of view_________________________________________ __________13°20'.
    Diameter of exit pupil______________________________ _____inch— 0. 30.
    Effective focal length of objective___________ —---------inches— 4. 123.
    Effective focal length of eyepiece------------ ---------- do----- 1. 374.
    Apparent field of view------------------------ _ . --------------40°.
    Eye distance (eye lens to pupil)------------------ - —inches— 1. 25.
    27
    TM 9-1600
    8	ORDNANCE MAINTENANCE
    .--NAME PLATE
    	RIVET c/	CT	EYE SHIELD	r-—	.
    X5	EYEPIECE CELL	^yTADAPTER	LQ--
    |  :  —]	SEPARATORAffifeBi^Xjj^VHELENS	—f z ,
    7	; V RETAINING RINgX^SX2ZAS=^EYEPIECE assEMBLy1Z/A ’
    \—field lens ; m x RETICLE ' -HiZtt -SCREW	, . 9- »' ■■'•—  ffiVFP
    ETCHING ON-^Jf ■ T \^bCKtw	© /zZ>	COVER
    U- fl | 11 J	THIS SIDElJ	, nKXpSCREW	z
    ®	RETAINING RING^/—\rING	c_dc.a/
    ------.	z Ph- ■ ■ ■ ■	j\\______________SCREW POSITIONING SCREW W	\\lOCKING SCREW _COVER
    A\ /	RETICLE CELLZ \\	//	\ SCREW
    I RETAINING RING-.	\\	//	SECTION A-A
    ---0----p—। -CZZ • C\ B°DY	(THROUGH AMICI PRISM) /ielescopl>\ \\	j \' r1	--JjK \ r* a r>
    ' P P	I	I
    —t—ESp	tuffitSw
    OBJECTIVE CELL-1	'-WEDGE
    OBJECTIVE -J	--HOLDER
    SCREW 	---AMICI PRISM
    OBJECTIVE ASSEMBLY-	RA PD 24116
    Figure 21. Elbow telescope M24, M25, M26.
    28
    TH 9-1600
    9-11
    DIRECT-FIRE TELESCOPES
    Section III
    CARE AND PRESERVATION
    Paragraph
    Cleaning and preserving materials------------------------------ 9
    Telescope mounts----------------------------------------------- 10
    Elbow telescopes--------------------------------------- _	— 11
    9. Cleaning and preserving materials.—a. Lubricants.
    Oil. lubricating, for aircraft instruments and machine guns (for all lubrication where oil is required).
    Grease, lubricating, special (for all lubrication where grease is required).
    b. Cleaning materials.
    Alcohol, ethyl (for cleaning optical parts).
    Solvent, dry-cleaning (for cleaning metal components).
    Paper, lens, tissue (for cleaning polished glass surfaces).
    Brush, camel’s-hair (for removing dust and lint from optics).
    10. Telescope mounts.—a. Oil cups are provided for the lubrication of the elevation worm and worm gear, and the telescope rotating worm and worm gear on all four mounts. Fill the cups with oil as required.
    b. The lateral adjusting worms are lubricated at assembly and should require no attention by using personnel.
    c. Apply a few drops of oil occasionally to the clamp pivot on the telescope holder.
    (I. Wipe off al] excess oil to prevent accumulation of dust and grit.
    e. Wipe off all dust and grit from the contact surfaces and locating surface on the telescope holder before assembling the telescope to the mount.
    /. Do not attempt to rotate the worms without first loosening the clamping screws.
    g. Keep the clamping screws tight at all times except when adjusting.
    11.	Elbow telescopes.—a. Care must be exercised in handling the telescopes to prevent damage to, or disturbance of, the optical system.
    b.	Wipe all dust and grit from the bearing surfaces and locating surfaces on the telescopes before assembling to the mounts.
    c.	Do not touch or attempt to wipe the lenses with the fingers or a cleaning cloth. Remove dust or grit with a camel’s-hair brush. Brush the glass lightly and then rap the brush against a hard object in order to knock out the small particles of dust that cling to the hairs.
    29
    TM 9-1600
    11-13
    ORDNANCE MAINTENANCE
    d.	To remove oil or grease from the lenses, apply alcohol with a camel’s-hair brush and wipe dry with clean lens paper. If alcohol is not available, breath heavily on the lens to moisten it and wipe dry as directed above. Repeat the operation until all traces of oi] have been removed.
    e.	Under no conditions whatever will polishing liquids, pastes etc., be used for polishing lenses or other parts.
    Section IV
    INSPECTION
    Paragraph
    Purpose of inspection________________________________________________________ 12
    Tools for inspection and repair______________________________________________ 13
    Tolerances___________________________________________________________________ 14
    Inspection requirements------------------------------------------------------ 15
    Facilities needed for inspection_____________________________________________ 16
    Basic inspection of telescope mounts---------------------------------------   17
    Basic inspection of elbow telescopes----------------------------------------- 18
    Action to be taken----------------------------------------------------------- 19
    12.	Purpose of inspection.—Inspection is made for the purpose of determining the condition of the instrument, whether repairs or adjustments are required, and the action necessary to place the instrument in serviceable condition.
    a. The basic inspection performed on an instrument is a preliminary inspection to determine its condition and to locate basic faults. As a result of this inspection, proper disposition of the instrument can be made and necessary action taken or recommended. Inspection forms (O. O. F. 7228 and O. O. F. 7229. fig. 22) are provided for recording the results of the inspection. Instructions concerning the entries to be made are printed on the back of the form.
    &. The detailed inspection and correction instructions in section V are performed by the instrument repairman. From these instructions he locates and then performs the specific repair required to place the instrument in serviceable condition. The procedure may vary with each instrument, depending on the faults indicated by the preliminary inspection. Inspection forms and methods used in connection with the detailed inspection are described in TM 9-2602.
    13.	Tools for inspection and repair.—An instrument repair kit containing common tools and supplies for instrument inspection and repair is furnished to ordnance maintenance companies. (This kit, repair, instrument, replaces kits previously issued as kit. repair, optical, for Field Artillery and kit, repair, optical, for harbor defense.) Most of the items in the kit, such as screw drivers, etc., require no de-
    30
    TM 9-1600
    13-15
    DIRECT-FIRE TELESCOPES
    scription as their uses are self-evident. The collimating telescope which is furnished with the kit is a small cylindrical prefocused telescope. It is used for inspecting the optics of a telescope and for setting up test fixtures. The collimating telescope does not require adjustment in use and is not to be disassembled in the field.
    14.	Tolerances.—Tolerances, or allowable errors, are specified where necessary to indicate the degree of accuracy required in performing certain adjustments. In general, an instrument is considered unserviceable if the error in any part exceeds the specified tolerance. However, it must be realized that the specified tolerance is intended to serve mainly as a guide for the inspector, and must be supplemented by the inspector’s good judgment. The repairman should not infer from these tolerances that he should not attempt to reduce the errors to closer limits if time and conditions permit.
    15.	Inspection requirements.—a. Telescope mounts should be checked for—
    Name plate data.
    Completeness.
    Appearance.
    Condition of paint.
    Condition of machined locating surfaces on mounting bracket and telescope holder.
    Smoothness of worm motions (lateral adjustment worm, elevation worm, reticle rotation worm).
    Action of clamps.
    Note.—O. O. F. 7228 is the same as O. O. F. 7229 except that it is not ruled. Instructions are printed on back.
    b. Elbow telescopes should be checked for—
    Name plate data.
    Completeness.
    Appearance.
    Sealing.
    Condition of paint.
    Condition of machined locating surfaces.
    Operation of eyeshield adapter.
    Definition.
    Reticle alinement.
    Collimation.
    Focus of eyepiece.
    Focus of objective (parallax).
    31
    TM 9-1600
    16-18	ORDNANCE MAINTENANCE
    16.	Facilities needed for inspection.—The inspection can be made with only a few common hand tools, but it will be facilitated if the following are available:
    a.	Sturdy work bench, affording clear vision to the front.
    b.	Collimating telescope.
    c.	V-block for elbow telescope.
    d.	Common hand tools (screw driver, wrenches, etc.).
    17.	Basic inspection of telescope mounts.—a. Record the serial number from the name plate. The name plate is located on the plug which secures the telescope holder.
    b.	Examine the telescope mount for completeness, appearance, condition of paint, and for broken or bent parts. The mounting screws, with their nuts and washers, are part of the telescope mount and should be assembled to it.
    c.	Machined locating surfaces on mounting bracket and telescope holder should be smooth and clean. The elbow telescope should fit easily into the telescope holder when the telescope clamp is opened, and should be held securely when the clamp is tightened.
    d.	Release the screws which tighten the clamping collars. Operate each worm (lateral adjustment worm, elevation worm, reticle rotation worm) through its complete range of motion and note any unusual conditions such as binding of the worm, backlash, or chatter. Worm parts in good condition should produce a smooth, even motion with no perceptible backlash. A slight amount of backlash is permissible in worm motions which are secured by means of clamping collars, but any perceptible backlash in the elevation worms of telescope mounts M26 and M28 (azimuth) is not permissible.
    e.	Tighten the screws on the clamping collars. The clamping action should be positive, and sufficiently strong to withstand possible accidental motion.
    18.	Basic inspection of elbow telescopes.—a. Record the serial number from the name plate. The name plate is located on the elbow cover of the telescope.
    b.	Examine the elbow telescope for completeness, appearance, condition of paint, and for broken or bent parts. See that setscrew openings in the telescope body are properly sealed.
    c.	The cylindrical bearing surface and flat locating surface on the shorter leg of the telescope should be smooth and clean.
    d.	Check eyeshield adapter to see that it clips securely into the locating groove, and that it can be engaged or disengaged with only normal hand pressure. Check condition of eyeshield.
    32
    TM 9-1600
    18
    DIRECT-FIRE TELESCOPES
    e.	Look through the telescope and examine the optical elements for signs of breakage, dirt, grease, moisture, and deterioration of
    0.0. F. 7229 INSPECTION OF ORDNANCE MATERIAL Sheet No. Organization			 Date of inspection	. Station	Inspected by		 Organization commander
    Item and Serial No.	Defects r.cxod	Action to be taken

    RA PD 9893
    Figure 22.—0. 0. F. 7229 (Inspection of Ordnance Material).
    adhesive balsam in the compound lenses. Defects can best be examined with the aid of the collimating telescope. The image should
    474171° 42
    33
    3
    TM 9-1600
    18-22	ORDNANCE MAINTENANCE
    appear sharp and clear, and the reticle should be in sharp focus. When observing a distant object, there should be no relative movement (parallax) between the object and the reticle as the eye is moved slightly from side to side or up and down. The image and reticle pattern should both be upright when the telescope is in normal operating position.
    19.	Action to be taken.—Instruments found defective must be repaired or adjusted to render them serviceable. Defects noted and action to be taken must be entered on the inspection form for each instrument. The action to be taken will be governed by the facilities available. If the facilities of the section do not permit satisfactory accomplishment of the repair or adjustment, pass the unserviceable instruments on to a higher maintenance echelon, and issue replacement items to the using arm.
    Section V
    MAINTENANCE AND REPAIR
    Paragraph General_______________________________________ ___ 20
    Detailed inspection and correction of telescope mounts______________ __________ 21
    Detailed inspection and correction of elbow telescopes_________________________ 22
    20.	General.—a. 'Die following operations may be performed only by qualified ordnance personnel. The using arm is prohibited from attempting them. Correction for defects in the telescope mounts is accomplished primarily by replacement of worn and broken parts. I he necessary disassembly and assembly is described in section VI.
    6. Correction for defects in the elbow telescopes is primarily a matter of adjustment to correct for optical defects, and replacement of damaged or broken optical components. Replacement of mechanical components other than the eyeshield and eyeshield adapter should seldom be required. The necessary repairs can generally be performed by the instrument section in the field. Repairs involving replacement of the telescope body, baking of paints or cementing of lenses should be performed only at an arsenal or base shop.
    21.	Detailed inspection and correction of telescope mounts.— Because of the simple construction of these telescope mounts, the preliminary inspection is sufficient to locate any faults and to indicate the specific repairs required.
    22.	Detailed inspection and correction of elbow telescopes.— Die repairman will use only the parts of the following instructions that seem to be necessitated by the results of his preliminary inspection.
    34
    TEXAS STATE COLLEGE FOR WOMEN
    LIBRARY	TM 9-1600
    DIRECT-FIRE TELESCOPES	22 .
    a. Preliminary.—To make the adjustments described below, the Amici prism must be secured in position and the other optical elements must be assembled in the relation shown in figures 21 and 23. Note that the reticle etching is on the side toward the eyepiece. The eyepiece and objective should be focused to at least a rough approximation, so that both the reticle pattern and the field of view are visible through the eyepiece. Optical elements must be clean. There is no provision for adjusting the Amici prism. The prism is correctly located in assembly by means of accurately machined metal surfaces, and if the prism is properly seated on these surfaces no further adjustment will be required. There is, however, a possibility of improper seating if dirt lodges on these surfaces during disassembly or reassembly, in which case the subsequent adjustments will be difficult or impossible to perform. This is particularly important in the case of the reticle adjustment. The prism should be properly seated and prism covers should be in place before any optical adjustments can be made.
    Z>. To test reticle alinement and collimation.— (1) Place the telescope in normal operating position, with the face of the locating lug accurately vertical and the eyepiece facing either right or left as in the telescope mount. The reticle pattern should appear upright and the principal horizontal line of the reticle pattern (fig. 6) should be parallel to a true level line. The tolerance, or allowable deviation, is plus or minus 0.5 mil at any point on the reticle line. The deviation can be estimated by comparison with the lettering on the reticle, which is approximately 2 mils high.
    (2)	Collimation is the adjustment by which the line of sight through the reticle center is made to coincide with the mechanical center axis of the telescope.
    (3)	A V-block (fig. 25) to fit the cylindrical bearing surface is required for performing the collimation test, but if a V-block is not available the telescope may be secured in the telescope holder of the mount and rotated by means of the reticle rotating worm. In either case, the effect is to permit rotation of the telescope about its mechanical center axis. The V-block is preferable as it eliminates the possibility of error due to misalinement of the telescope holder.
    (4)	The reticle center point for elbow telescope M24 is the top point of the central vertical line. The reticle center point for elbow telescopes M25 and M26 is the center of the top (zero range) horizontal line. (See fig. 6.)
    (5)	To test for collimation, direct the reticle center point on a clearly defined distant reference point, and then rotate the telescope
    35
    TM 9-1600
    22
    ORDNANCE MAINTENANCE
    about its mechanical center axis. If the collimation is correct, the reticle center point will not move off the reference point. If collimation is incorrect, the reticle center point will follow a circular path through the reference point. The maximum deviation from the reference point is the collimation error.
    (6)	The tolerance for collimation error is 0.5 mil. It should be understood that a telescope may be continued in service even if the collimation error is rather large, as the construction of the telescope mount permits adjustment to compensate for this error. However, accuiate collimation simplifies procedure when changing telescopes.
    c.	To correct reticle alinement ami collimation.— (1) The reticle is in coirect adjustment when the reticle center agrees with the mechanical center of the telescope (collimation), and when, with the telescope in normal operating position, the reticle pattern appears erect (reticle alinement).
    (2)	The reticle cell, containing the reticle, is supported between a cast shoulder in the telescope body and the reticle cell retaining ring (figs. 23 and 24). This method of support permits rotation of the reticle cell for reticle alinement. I he reticle cell is also supported laterally and vertically by four positioning screws which permit shifting the reticle cell for collimation adjustment.
    (3)	Correct collimation is desirable but, as previously noted, adjustment can be made in the telescope mount to correct for collimation error. Correct reticle alinement, on the other hand, cannot be obtained by any adjustment other than that of the reticle within the telescope. The reticle rotation worm of the telescope mount merely brings the reticle pattern into parallel with the field of view, so that any tilt of the reticle results in a corresponding tilt of the image in the field of view.
    (4)	To adjust for reticle alinement remove the eyepiece (par. 25tz), loosen the reticle cell retaining ring locking screw, and back off the reticle cell retaining ring a small amount to allow rotation of the reticle cell. Loosen two of the reticle cell positioning screws (one lateral and one vertical), leaving the other two screws in place if necessary to retain the collimation adjustment. Turn the reticle cell in the required direction, then tighten the reticle cell positioning screws and retaining ring, assemble the eyepiece, and check alinement. To check alinement, place the elbow telescope in a leveled V-block (fig. 25) with the flat locating surface vertical. (The image of an object in the field of view will then appear without tilt unless the Amici prism has been incorrectly assembled.) Compare the horizontal reticle line with a
    36
    TM 9-1600
    22
    DIRECT-FIRE TELESCOPES
    true horizontal line in the field of view. Repeat the procedure until satisfactory adjustment is obtained.
    (5)	To adjust for collimation, shift the reticle laterally or vertically by means of the reticle cell positioning screws. Check the reticle centering by turning the telescope in the V-block and noting any deviation of the reticle center point. Repeat the procedure until satisfactory adjustment is obtained.
    d.	To test focus of eyepiece.—The eyepiece is correctly focused if the reticle pattern is sharp and clear when viewed through the collimating telescope.
    e.	To correct focus of eyepiece.—(1) The eyepiece focus depends only on the reticle position. Eyepiece focus is correct when the reticle etching is sharp and clear.
    (2)	To focus the eyepiece, loosen the eyepiece cell locking screw and screw the eyepiece cell in or out to obtain sharpest definition of the reticle pattern. Check results with the collimating telescope. When the best focus has been obtained, tighten the locking screw to retain the adjustment.
    f.	To test focus of objective.—The objective is correctly focused if there is no parallax between the image and the lines near the center of the reticle when viewing an object at a distance of about 125 yards.
    g.	To correct focus of objective.— (1) Parallax is due to the fact that the etched side of the reticle is not lying in the focal plane of the objective. This defect can be corrected by focusing the objective to make the focal plane coincide with the reticle etching.
    (2) To focus the objective, direct the telescope on an object about 125 yards distant. Remove the objective cell locking screw and screw the objective cell in or out to obtain sharpest definition of the object. Assuming that the eyepiece has been correctly focused, the objective position which provides sharpest definition will also be the position for minimum parallax. Check results with the collimating telescope. When the best focus has been obtained, tighten the locking screw to retain the adjustment.
    (3) Always check for parallax any time an optical element has been moved or replaced.
    37
    TM 9-1600
    22
    ORDNANCE MAINTENANCE
    Pj H .11	X. \	\ RETICLE CELL
    K 7 I 'I'''	|	\ \ \ POSITIONING
    !> k I l \ \ \ SCREWS
    Reticle’Ll	J / S >
    cellJ	Zz7
    ^3	RA PD 24123
    Figure 23.— Reticle adjustment.
    38
    DIRECT-FIRE TELESCOPES
    TM 9-1600
    22
    39
    >W0W	___
    -a *	■	mi't? >
    I****
    , «-	.., Ukani.*
    < w. t ywwiM^i -'• 2 ***^
    EYEPIECE CELL
    11 W 1 w®SSSH’iwl ®3B1 i—
    Ml! W	JEYEPIECE CELL
    ’ll	31*L0CK1NG SCREW
    ■JMJI.
    RETICLE CELL
    RETICLE CELL RETAINING j __EiSfc--	” RETAINING RING
    RING LOCKING SCREWj | B
    /I II	"RET1CLE CELL
    RETICLE CELL POSITIONING SCREWS ^'TW W
    OBJECTIVE CELL LOCKING SCREW ^****’*2 .	> W?’ « CIr
    r”"^SdEiZ=Z'«S7^SK jt FPRISM
    ra PD 24122 ^>>5: y1 r "■* ■"■■■■■-■'"
    ' OBJECTIVE CELL
    Figure 24.—Elbow telescope M24, M25, M26, cut away view.
    TM 9-1600
    22
    ORDNANCE MAINTENANCE
    Figure 25.—Elbow telescope in V-block.
    40
    RA PD 9605
    TM 9-1600
    DIRECT-FIRE TELESCOPES	23-24
    Section VI
    DISASSEMBLY AND ASSEMBLY Paragraph
    General______________________________________________________________ 23
    Disassembly	of telescope mounts------------------------------------- 24
    Disassembly of elbow telescopes--------------i----------------------- 25
    Assembly____________________________________________________________  26
    23. General.—a. To preserve the parts of the instrument, it is necessary to exercise care and close attention during disassembly, cleaning, and adjustment. The extent of disassembly for any given repair job is determined by the repairman when he makes his detailed inspection.
    &. All optical elements and metal components should be carefully marked or tagged as they are disassembled to insure correct positioning in the instrument on reassembly. If parts are not so marked or tagged, considerable difficulty may be encountered in the final adjustment. Reference marks should be scribed when deemed advisable. An indelible pencil or diamond may be used for marking on unpolished surfaces of optical elements. Metal components may be scribed, marked, or tagged.
    c. Defective parts should be replaced from stock. Replacement of defective optical elements must be carefully checked inasmuch as replacement of even one optica] element may change the optical characteristics of the telescope and render readjustment necessary. Replacement of metal components is easily accomplished since the components are all standardized and available as replacements. Keep in mind, however, that the replacement of certain mechanical components which affect optical dimensions, such as the reticle cell, may cause parallax and affect the final adjustment of the telescope.
    24. Disassembly of telescope mounts.—The disassembly procedure outlined below is based on the telescope mount M26 (fig. 26). The procedure for any of the other telescope mounts described is generally the same. Division of the disassembly procedure into four steps is for convenience in performing complete disassembly; partial disassembly may be performed without regard to these steps. Refer to figures showing assembly and sectioned views of the particular telescope mount (figs. 7 to 20).
    a.	First step (fig. 26 (?)).—Remove telescope holder assembly. To do this—
    (1)	Remove locking screw in retaining plug and unscrew retaining plug.
    41
    TM 9-1600
    24-25
    ORDNANCE MAINTENANCE
    (2)	Drive out the taper pin in the worm collar and slide the collar off the worm shaft. Thread the worm out of its housing.
    (3)	Remove clamping screw with nut and washer.
    (4)	Remove telescope holder assembly.
    b.	Second step (fig. 26 ®).—Remove the elevation worm parts. For telescope mounts M27 and M29 these parts consist of a screw-driver operated worm and a clamping screw similar to the reticle rotation worm parts. For telescope mounts M26 and M28, proceed as follows :
    (1)	Drive out the taper pin in the worm knob and slide the knob off the worm shaft. Remove the felt washer.
    (2)	Remove the damping screw which secures the worm plunger plug. Unscrew the plug and remove plunger and spring underneath.
    (3)	Remove the clamping screw which secures the ball cap and the dog-point screw which secures the ball socket. Unscrew the ball cap. Thread the worm out of the housing and remove it together with the ball socket.
    c.	1 hi rd, step (fig. 26 @).— (1) Remove the screw which secures the round nut to the elevation gear, and remove the round nut. Slide the elevation worm housing off the gear.
    (2)	Remove the screw which secures the round nut to the spindle and remove the round nut.
    (3)	Remove the worm and two clamping screws which secure the spindle to the mounting bracket.
    d.	Fourth step (fig. 26 @).—Slide the spindle assembly out of the mounting bracket. An arbor press will be required for performing any further disassembly of the spindle and gear, as these parts are pressed together under force fit in addition to being pinned. If replacement is required, a complete spindle assembly will generally be used.
    25. Disassembly of elbow telescopes (figs. 24 and 27).___a. Dis-
    assembly of eyepiece parts.—(X) Remove the eyeshield adapter by sliding it off the telescope body.
    (2)	Remove the eyepiece cell locking screw.
    • (3) Unscrew the eyepiece cell until the threads are clear of the telescope body and then carefully remove the cell.
    (4) To remove the reticle, remove the reticle cell retaining ring locking screw and unscrew the reticle cell retaining ring. Loosen the reticle cell positioning screws and then carefully remove the reticle cell.
    b.	Disassembly of Amici prism.—Remove the prism cover screws and unscrew the prism covers. One side of the prism holder will be
    42
    TM 9-1600
    DIRECT-FIRE TELESCOPES	25-26
    found to contain a slot through which a pointed tool can be inserted into a hole in the wedge underneath. Pull the wedge out through this end of the prism holder, and then lift out the prism holder and Amici prism.
    c.	Disassembly of objective.— (1) Remove the objective cell locking screw.
    (2)	Unscrew the objective cell and then carefully remove the cell from the telescope body.
    d.	Removal of lens from cell.—To remove a lens from its cell, remove the small locking screw in the side of the cell and unscrew the retaining ring. Figure 27 shows the optical elements mounted in their cells.
    26.	Assembly.—a. To assemble, reverse the disassembly procedure. Necessary adjustments are performed as indicated in previous parts of this manual.
    b.	All parts which have been removed from the instrument should be carefully cleaned before assembly.
    (1)	Optical elements should be cleaned with ethyl alcohol. Care must be exercised to prevent alcohol from coming in contact with the edges of compound lenses as the lens cement is soluble in alcohol. If pencil marks have been placed on the unpolished surfaces of lenses or prisms, avoid removing them to prevent difficulty when assembling. Polish the optical element with lens paper. Remove dust and dirt with an air bulb and a small,, clean camel’s-hair brush.
    (2)	Metal components should be cleaned in dry-cleaning solvent and quickly dried in air. Caution: Do not clean metal components in dry-cleaning solvent when the optical elements have not been removed. After cleaning, lubricate worms, worm gears, and similar moving parts by applying a light coating of grease.
    c.	When replacing the eyepiece and objective cells of the elbow telescopes, apply a very light film of grease to the threaded part of the cell. The grease film facilitates assembly and is effective in sealing the telescope. There should be just enough grease to make the joint air- and moisture-tight, but not enough to overrun onto the lenses.
    d.	Plug the recesses above the various adjusting screws, etc., with plugging cement of the same color as the instrument. Smooth the cement to hide the openings as completely as possible.
    e.	After assembly and adjustment, the various parts aiid mechanisms should be again inspected according to the procedure given in section IV.
    43
    TM 9-1600
    26
    ORDNANCE MAIN TEN A N CE
    TELESCOPE HOLDER ASSEMBLY	^^WORM COLLAR
    f'	\\ Z ?	«=»------TAPER PIN
    C |L/// III I 1	/r\	LOCKING SCREW
    (dSfr? \\AjjL \ W/	II // m *~t-----RETAINING PLUG
    CLAMPING SCREW-' V ----------MA--
    "-WORM HOUSING
    ------------WORM
    RA PD 24118
    ® First step.
    Figure 26.—Disassembly of telescope mount M26.
    44
    TM 9-1600
    26
    DIRECT-FIRE TELESCOPES
    CLAMPING SCREW .
    WORM PLUNGER PLUG^^^^^^
    SPRING^ /	X——	7
    plunger:	।
    DOG POINT SCREW--22b	\V\	[)
    CLAMPING SCREW'—I 1
    fl u3. V
    ELEVATION WORM--
    xjcEE&	BALL socket
    pi -BALLCAP
    -------FELT WASHER
    TAPER PIN---<4	WORM KNOB
    X~--—RA PD 24119
    ® Second step.
    Figure 26.—Disassembly of telescope mount M26- Continued.
    45
    TM 9-1600
    26
    ORDNANCE MAINTENANCE
    g—---SCREW
    ROUND NUT
    --------SPINDLE )T / CLAMPING SCREWS—i
    LL-L XL
    Q'MxxLf
    — ROUND NUT --------------------ELEVATION GEAR
    ELEVATION WORM HOUSING
    RA RD 24120
    ® Third step.
    Figure 26.—Disassembly of telescope mount M26—Continued.
    46
    TM 9-1600
    26
    DIRECT-FIRE TELESCOPES
    \.	\\//M0UNTING BRACKET
    ^SPINDLE ASSEMBLY
    V v\ T^--^ RA PD 24,21
    @ Fourth step.
    Figure 26.—Disassembly of telescope mount M26—Continued.
    47
    TM 9-1600
    26	ORDNANCE MAINTENANCE
    48
    EYESHIELD ADAPTER—
    WEDGE--	--- RETICLE CELL RETAINING	\\
    RING LOCKING SCREW	RX	!
    HOLDER—
    [EYEPIECE CELL	Z'
    AMICI PRISMi	[“[LOCKING SCREW ffW
    \	m\ v\V W
    OBJECTIVE CELL \ i
    LOCKING SCREW I \	\\\ Y\
    \ U	(|O\\	'EYEPIECE CELL
    yfe3 z~"\ ffl	'	\	I	\	'RETICLE CELL RETAINING RING
    MdWA	z^AT^P I	'RETICLE CELL
    / / /// \\ / — OBJECTIVE CELL	q ,Z	'RETICLE CELL POSITIONING SCREWS
    COVER SCREWS (COVERS NOT SHOWN)
    RA PD 24117
    Figure 27.—Elbow telescope M24, M25, M26, exploded view.
    TM 9-1600
    27-28
    DIRECT-FIRE TELESCOPES
    Section VII
    PAINTING
    Paragraph
    Touch-up painting______________________________—_------------------------- 27
    Over-all painting_________________________________________________________ 28
    27. Touch-up painting.—Small scratches or worn spots, as well as unavoidable blemishes caused by assembly or adjusting operations, should be touched up with an air drying enamel of a practical color match of the original finish.
    28. Over-all painting.—a. Occasionally, there are received for repair at the arsenals instruments which function improperly because paint has entered bearings and bearing surfaces and has splashed on scales and lenses. The effect of paint on bearing surfaces and in bearings is obvious. The removal of paint from scales and lenses has resulted in the scratching of scales and damage to the lenses.
    1). The painting of fire-control instruments by the using service is therefore prohibited.
    c. The painting of instruments by ordnance personnel must be supervised by a person who is familiar with the functioning of the instruments and who is in a position to caution against the application of paint to scales, lenses, bearing surfaces, sight seats, etc. The paint to be used depends on the instrument to be serviced.
    d. Exterior parts will be universally painted olive-drab.
    474171°—42---4
    49
    TM 9-1600
    ORDNANCE MAINTENANCE
    Appendix
    LIST OF REFERENCES
    1.	Standard Nomenclature Lists.
    a.	Direct fire sights for 3-inch antiaircraft and 90-mm
    antiaircraft gun materiel____________________________SNL F-224
    b.	Instrument repair kit___________________________SNL F-206
    c.	Materiel, cleaning and preserving, and tools and
    equipment used therewith_____________________________ SNL K-l
    d.	Current Standard Nomenclature Lists are as tabulated here. Au up-to-date list of SNL’s is maintained as the Ordnance Publications for Supply Index (OPSI).
    2.	Technical Manuals.
    a.	Cleaning, preserving, and lubricating materials_TM	9-850
    b.	3-inch antiaircraft gun materiel (mobile)_______TM	9-360
    c.	90-mm antiaircraft gun materiel Ml and Ml Al____TM	9-370
    d.	Instruction guide, the instrument repairman_____ TM	9-2602
    50
    TM 9-1600
    INDEX Paragraph Page
    Application of instruments to guns________________________________ 2	2
    Assembly of telescopes and mounts________________________________ 26	43
    Care and preservation:
    Elbow telescopes___________________________________________   11	29
    Telescope mounts_________ ____ _ ________________________ 10	29
    Cleaning materials___________________________________________ 9	29
    Collimating telescope___ .	________________________________ 13	30
    Difference in models_________________________________________ 3	2
    Disassembly:
    Elbow telescope.,---------------------------------------- 25	42
    General instructions--------	. — ---------------------- 23	41
    Telescope mounts------------ ---------------------------- 24	41
    Elbow telescopes M24, M25, M26:
    Application to guns___________________________________________ 2	1
    Assembly_____________________________________________________ 26	43
    Basic inspection--------------------------------------------  18	32
    Care and preservation________________________________________ 11	29
    Characteristics_______________________________________________ 2	1
    Description___________________________________________________ 8	27
    Detailed inspection and correction___________________________ 22	41
    Disassembly_________________________________________________  25	42
    Lubrication__________________________________________________ 11	29
    Optical characteristics_______________________________________ 8	27
    Eyepiece:
    Assembly_____________________________________________________ 26	43
    Disassembly__________________________________________________ 25	42
    Focus________________________________________________________ 22	41
    Facilities for inspection and repair_____________________________ 16	32
    Forms for inspection_____________________________________________ 12	30
    Inspection:
    Action to be taken___________________________________________ 19	34
    After assembly_______________________________________________ 26	43
    Basic, elbow telescopes______________________________________ 18	32
    Basic, telescope mounts______________________________________ 17	32
    Facilities needed____________________________________________ 16	32
    Forms_______________________________________________________  12	30
    Purpose------------------.------------------------------- 12	30
    Requirements_______________________________________________   15	31
    Tolerances___________________________________________________ 14	31
    Tools________________________________________________________ 13	30
    51
    TM 9-1600
    INDEX
    Paragraph Page
    Kit, instrument repair_____________________________________ 13	3g
    Lubricants_________________________________________________ 9	29
    Lubrication:
    Elbow telescopes____________________________________________ n	29
    Telescope mounts___________________________________________ 10	29
    Upon assembly______________________________________________ 26	43
    Maintenance and repair:
    Elbow telescopes ______________________________________     22	41
    General instructions_______________________________________ 20	34
    Telescope mounts___________________________________________ 21	34
    Metal components_______________________________________________ 23	41
    Objective:
    Assembly--------------------------------------------------- 26	43
    Correction of focus____________’_______________________ 22	41
    Dissassembly_______________________________________________ 26	43
    Test for focus_____________________________________________ 22	41
    Optical characteristics, elbow telescopes_______________________ 8	27
    Optical elements:
    Cleaning----------------------------------------------- 11, 26	29,43
    Removal from cell__________________________________________ 25	42
    Replacement________________________________________________ 23	41
    Tagging and marking________________________________________ 22	41
    Painting:
    Over-all--------------------------------------------------- 28	49
    Touch-up___________________________________________________ 27	49
    Parallax, correction and test________________________________   22	41
    Prism, Amici:
    Assembly--------------------------------------------------- 26	43
    Disassembly________________________________________________ 25	42
    Seating---------------------_-------------------------- 22	41
    Reticles:
    Alinement and collimation__________________________________ 22	41
    Description_________________________________________________ 3	2
    Sealing------------------------------------------------------   26	43
    Telescope mounts:
    Application to gun__________________________________________ 2	1
    Basic inspection____________'__________________________ 17	32
    Characteristics_____________________________________________ 2	1
    Description:
    M26____________________________________________________ 4	9
    M27____------------------------------------------------ 5	iQ
    M28---------------------------------------------------- 6	19
    M29---------------------------------------------------- 7	23
    Differences among__________________________________________  3	2
    Lubrication________________________________________________ 26	43
    52
    TM 9-1600
    INDEX
    Paragraph Page
    Tolerances________________________________'-------------------- 14	31
    Tools for inspection and repair------ -------------------- 13	30
    V-Block___________________________________________________ 22	41
    [A. G. 062.11 (4-28-42).J
    By order of the Secretary of War:
    G. C. MARSHALL.
    Chief of Staff.
    Official :
    J. A. ULIO,
    Major- General.,
    The Adjutant General.
    Distribution :
    IBn 9(1); IC 9(3).
    (For explanation of symbols see FM 21-6.)
    U. S. GOVERNMENT PRINTING OFFICE: I94S
    53
    jjgygOY
    ■'s ' ’ ' ■''
    UNT LIBRARIES DENTON TX 78203