TM 9-305 ( 75-Mm Materiel, M1897 and Modifications

8/14/2019 TM 9-305 ( 75-Mm Materiel, M1897 and Modifications

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TM 9-305

WAR DEPARTMENT

TECHNICAL MANUAL. o~~~~~~~.75-MM GUN MATERIEL, M1897

AND MODIFICATIONSMarch 31, 1941_z--:-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


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*TM 9-3051-2

TECHNICAL MANUALNo. 9-305 J

WAR DEPARTMENT,WASHINGTON, March 31, 1941.

75-MM GUN MATERIEL, M1897, AND MODIFICATIONS

Prepared under direction of theChief of Ordnance

ParagraphsCHAPTER 1. General - -- - - - - - - - - - - - - - - -

2. Guns and carriages.Section I. Data - - --- - - - - - - - -II. Description and operation -. .III. Disassembly and assembly --

IV. Inspection and adjustment.V. Malfunctions ---------

VI. Care iand preservation ----3. Sighting and fire-control equipment.

Section I. Sighting equipment ------II. Fire-control equipment -----4.5.6.7.8.

Ammunition ---- - - - - - -- - - --- -Limbers and caissons (for horse-drawn artillery) -Spare parts and accessories..........Subealiber equipment --- ---------Material affected by gas ------------

APPENDIX. List of references___INDEX -.....-- ---

1-34-5

6-1011-2526-2829-3031-4243-5152-5859-7071-7677-7879-9495-97

Page........... 193.... - - - - - - 197

CHAP'rTE 1GENERAL

ParagraphPurpose ----------.--------------------------._--- ------------ ----- - 1Scope -- ____-----------_---_-______,-_-__________________- 2References --- - -.-.-.----------------------------------.--.--.--.-- 3

1. Purpose.-This manual is published for the information andguidance of the using arms and services.

2. Scope.-a. In addition to description and figures, this mnanualcontains instructions for the operation. inspection, disassembly and as-sembly, repair, and care and preservation of the mnat6riel.

*This pamphlet supersedes TR 320-95, March 25, 1925 (including C1, January 3, 1927), andin part TR 1305-A, February 1, 1933.195667-41-1


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Tl 9-3052-3 ORDNANCE DEPARTMENT

b. Disassembly and assembly and such repairs as may be handledby the battery personnel will be undertaken only under the super-vision of an officer or the chief mechanic.

c. In all cases where the nature of the repair, modification, or ad-justment is beyond the scope and/or facilities of the battery personnel,the local or otherwise designated ordnance service should be informedin order that trained personnel with suitable tools and equipmentmay be provided or proper instructions issued.

3. References.-All Technical Manuals, Field Manuals, FiringTables, Standard Nomenclature Lists, and other publications per-.taining to the materiel described herein are listed in the appendix.

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TM 9-3054-55-MM GUN MATERIEL, M1897, AND MODIFICATIONS

CHAPTER 2GUNS AND CARRIAGES ParagraphsData----------------------- 4-5

Description and operation - _---------- 6-10Disassembly and assembly----------- 11-25Inspection and adjustment ----------- 26 28Malfunctions ------------------ 29-30Care and preservation -------------- 31-42

SECTION IDATA

Data pertaining to guns ------ --... ____-----------Data pertaining to gun carriages -- - - .---------

4. Data pertaining to guns.-a. Weight.

I'aragraph-- . ..........._ _ ___ _ _ 5

75-mm gun

M1897 -- - - -- -- -M1897A2 ---- ---M1897A3 ---- -- -M1897A4 -------

Weight (pounds)

1, 0151, 0351, 0351, 035

b. Rate of fire.-A maximum rate of fire of 25 to 28 rounds perminute may be attained, but the advisable rate is 6 rounds. Thegun may be loaded at any angle of elevation or depression.5. Data pertaining to gun carriages.-a. General.

75-mm gun carriage M1897 M1897MIA2

Weight of gun and carriage,complete (without acces-sories) . ....ounds 2, 657 2, 657Length of recoil .. inches_ 44. 9 44. 9

Height of axis from groundinches 40. 4 40. 4

Maximum elevation degrees__ 19 193

M1897A4 I M2AI M2A2 M2A3

3, 00744 . 9

44 . 419

3, 44741 . 5-46-0

47%46

3, 44741 . 5-46-0

3, 22544. 9

47% 4735s46 4530'

Section I.IT.III.IV.

V.VI.

------ - - - - - - - - - - - - -~~~~.


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TM 9-3055-6 ORDNANCE DEPARTMENT

75-mm gun carriage

Maximum depressiondegrees -Maximum traverse, right

degrees_Maximum traverse, left

degrees_

M1897

1033

M1897MIA2

1033

M1897A4 M2A1

10 103 453 40

b. Table of recoil mechanisms and carriages.-The table belowgives the guns and recoil mechanisms (columns one and two) whichare mounted on any carriage (column three). Reading across, anyof the- guns or recoil mechanisms listed in any one row may bemounted on any of the carriages in the same row.

Gun

M1897M1897A1M1897A2M1897A3M1897A4M1897A2M1897A4M1897A2M1897A4M1897A2M1897A4

Moun carriage5-mmecoilchaniom gu n carriage

MI 897A3M1897A6

M1897A5

M1897A7

M2

M1897M 1897A2M1897M1M1897M1A2M1897A4M2A1M2A2M2A3

M2A1M2A2M2A3

SECTION IIDESCRIPTION AND OPERATION

ParagraphDescription of 75-nm guns ......................................... _ 6Description of breechblock .-......._____----------_ --------------- 7Operation of breech and firing mechanism -------- '_____----- 8D escription of carriages ---------- - -------------------- ----- ---------- 9Operation of carriages ------------ __________________-____-- -------- 10

6. Description of 75-mm guns.-a. 311897.-(1) The gun(fig. 5) is of French design. A number of these weapons were pur-chased by the United States. Similar guns were manufactured in

4

M2A2 M2A3

10 110030'45401 3

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75-MM GUN MATERIEL, M31897, AND MODIFICATIONSthis country. The parts of the Amnerican and French manufac-tured guns are identical and therefore interchangeable.

(2) The gun is thile built-up type. Name and model are stampedon the left side of breech hoop. Name of manufacturer, year ofmanufacture, serial number, and weight, including breech mecha-nism, are stamped on the muzzle. Data on guns bought from Francewill be found on top of breech end.b. M1897A4 and M1897A2.-(1) The M1897A4 gun (fig. 6) is

a modification of the 75-mm gun, M1897 (French). The modifica-tion consists of the removal of rollers and sweeper plates with feltpads, and elimination of a portion of the jacket of the gun whichis replaced by steel rails and bronze strips attached to supports onthe gun.

(2) The M1897A2 gun is standard for new manufacture and issimilar in design to the 75-mm gun, M1897A4.7. Description of breechblock.-a. The breechblock (fig. 7) isthe Nordenfeld eccentric screw type, cylindrical in shape, andthreaded on its exterior to fit the breech recess. It has a largediameter compared with the caliber of the gun due to the axis ofthe breech recess and breechblock being below the axis of the boreof the gun. With this type the breechblock remains in the breechrecess during the action of both loading and firing, and the openingand closing of the breech is accomplished by rotating the breechblock156 around its axis by means of the operating handle. This move-ment alternately locates the loading hole and the firing pin in linewith the chamber of the gun, the movement being limited in eachdirection by stops against which the breechblock arm strikes. Whilethe mechanism is in the closed position, it is automatically lockeduntil released by action of recoil. The rim of the rear sight servesas a cam to trip the breecllblock latch.

b. The gun cannot be fired until the breechblock is rotated to thefully closed position, as only at that point is the firing pin in linewith the primer. Rotation of the breechblock to the loading posi-tion automatically ejects the empty cartridge case.

c. Two leveling plates in the top of the breech hoop form a surfaceparallel with-the bore, for the application of the gunner's quadrant.

8. Operation of breech and firing mechanism.-a. Breechmechanism.-(1) To open breech.-Unlatch breechblock latch bypressing on operating handle plunger with the thumb. Grasp op-erating handle with both hands toward the forward position. Thiswill protect the little finger of left hand from danger of injury by

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TM 9-3056-8


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TI 9-3058-9 ORDNANCE DEPARTMENTcrushing between the pawl and rear sight. Pull upward and pushover to left until breechblock arm stops against breechblock stop.

(2) To close breech.-Grasp operating handle as in opening thebreech, and pull to the right and down until breechblock arm strikesprojection stop on lower right on breech face. At the end of thismovement the inner end of breechblock latch springs into the groovesin the latch catch in breech face of the gun, latching the breech mech-anism in closed position.

b. Firing mnechanism.-(1) To fire the piece, pull lanyard sharplydown and to the right and release lanyard. This allows the hammerto be thrown forward against the firing pin by means of the firingrack spring with sufficient force to explode the primer.(2) Safety piece (fig. 7) is provided to prevent accidental firing.The safety piece screws into the threaded recess in the breechblockarm, and may be located at two different points. These two pointsare marked Safe and Fire on the outer surface of the breechblockarm. (On guns of French manufacture, these two points are markedTir and Route.)

9. Description of carriages.-a. 111897, M1897A2, M1897MI,M1897MIA2, and M1897A4.-(1) General.-(a) These gun car-riages are of the hydropneumnatic, constant recoil type in which thegunl when fired recoils a sufficient length to permit the carriage toremain stationary.

(b) The 75-mm gun carriage M1897 (French) (fig. 9), was de-signed and manufactured in France. The 75-mm gun carriagesmanufactured in this country are designated M1897MI.

(c) When the M1897 or M1897MI carriages are equipped withhandspike, model designation of the M1897 carriage is changed toM1897A2 and of the M1897MI carriage is changed to M1897MIA2.

(d) When the M1897 (fig. 9), M1897A2, M1897MI (fig. 17), andM1897MIA2 (fig. 11) carriages are equipped with high speed adapt-ers, their model designation is changed to M1897A4 (fig. 12).

(2) Recoil mechanismn.-(a) The recoil mechanism controls theforce created by firing and checks movement of recoiling mass in agradual manner so as not to cause displacement of the carriage. Therecuperator system of the mechanism returns the recoiling massinto battery in order that the gun may be fired again.

(b) All recoil mechanisms, except the M1897, have been equippedwith a respirator, which acts in conjunction with the recuperator inregulating counterrecoil at different temperatures. The respirator headhas four indentations in which the respirator cap spring seats when thevalve is rotated. These indentations are numbered 0, 1, 2 and 3, indi-

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TXV 9-30575-MM GUN MATERIEL, M1897, AND MODIFICATIONS 9

cating the number of holes which may be opened to allow escape ofair from the recoil cylinder during counterrecoil.

(3) Elevating mechanisrm.-Locatedbetween rocker and cradle. Itsfunction is to elevate or depress the gun with reference to the rocker.Thus the gun can be laid to the desired angle of elevation for rangewithout disturbing the laying for angle of site or the line of sight ((5)below).

(4) Range rack and range scale moanting.-Range rack (fig. 15),range scale, and range rack guide, front, have engraved scales whichcorrespond to the various ranges. The scales are for setting the gunin elevation or depression. Spacing of the graduations is such thatwhen the gun is elevated or depressed, the graduation opposite the in-dex indicates the actual range. The range rack and the range scaleare graduated for range in meters. The range rack registers for every100 meters, and the range scale for every 50 meters. The range rackguide, front, is graduated for every 2 mils. Thus to set the gun for agiven range, elevate or depress gun until corresponding graduation ofthe scale is opposite the index. If the range is given in meters thescale on the rack is used. If it is given in mils the scale on the rangerack guide, front, is used.

(a) Range scale is located above elevating crank on right ofcarriage.(b) Any movement between rocker and cradle is indicated by the

range scale.(c) Index marks on front and rear guides register the range and

elevation on the range rack scale and range rack.(5) Angle of site mechanism.-(a) The angle of site mechanism is

located between trail and rocker, and provides means for elevating ordepressing the rocker with reference to the trail. By means of thismechanism the rocker can be laid to the desired angle of site withoutdisturbing the angle of elevation.

(b) The angle of site handwheel (figs. 11 and 16) is perforated withtwelve holes which can be engaged with its angle of site handwheellatch (fig. 16) thus locking the angle of site mechanism. The outerface of the angle of site handwheel is divided into 16 equal spaceswhich are stamped and numbered. One complete turn elevates ordepresses the rocker 16 mils.

(c) The angle of site pointer (figs. 11 and 16) is a reference forreading graduations on the outer face of the angle of site handwheel.

(6) Traversing mechanisn.-The carriage can be trained on a tar-get by shifting the trail. A means is provided, however, for closertraining through the traversing mechanism. In traversing the carriage

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TM 9-3059 ORDNANCE DEPARTMENT

the front of the trail slides laterally on its bearings on the axle, describ-ing an arc about the spade. Thus during traverse one wheel advancesslightly ahead of the other.

(7) Shield.-The shield is for protection of the gun crew. Thethree types of shields are a four-piece shield of American manufacture,a four'piece shield of French manufacture, and a seven-piece shield.The American four-piece shield is interchangeable with the Frenchfour-piece shield, and either may be used to replace the seven-pieceshield. However, the seven-piece shield cannot be substituted on acarriage fitted for either type of four-piece shield.

(8) Wheels.-There are two types of 14-spoke wheels, one steel-tiredand the other rubber-tired. They are interchangeable on M1897 andM1897MIA2 carriages.

(9) Wheel fastenings.-The wheel fastenings consist of axle collarsfitted with leather washers and keyed to the axle at the inner ends ofthe hubs, and axle caps fitted with leather washers held in position bylinchpins.

(a) Axle collars are rigidly keyed to the axle and take the lateralthrust of the wheels when traveling.(b) Axle caps are held in place by means of linchpins. The outer

surfaces of the axle caps bear against the linchpins. The axle capsare so made that there are three separate surfaces that can be broughtto bear against the sides of the linchpins, each surface being higherthan the other. Thus a means of adjustment for end play is pro-vided. By varying the thickness of the washers in hubs, axle col-lars, and axle caps, end play may be eliminated.

(e) The linchpins are provided with latches which are forceddown over the ends of the axles clamping the pins in position.Leather thongs hold the linchpin latches in position.

b. M1897A4.-(1) The carriage (fig. 12) is a modified 75-mmgun carriage, M1897 or M1897MI. This modification consists of theremoval of seats, seat supports, shaft brackets, steel or rubber-tiredwheels, brake worm support bolts and washers, brake crank pin andbrake crank, and equipping the carriage with a high speed adapter,pneumatic tires mounted on disk and rim wheels, and an internalexpanding brake mechanism.

(2) In other respects the carriage is the same as the M1897carriage.c. M2A2.-(1) The carriage (fig. 27) is of the split trail typebuilt for high speed transport and equipped with pneumatic tired

disk and rim wheels with internal expanding brakes. Equilibratorsneutralize unbalanced weight of the gun and recoil mechanism.

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75-MM GUN MATERIEL, M1897, AND MODIFICATIONSTM 9-305

9When traveling an offset drawbar provides the spades with roadclearance and two locking mechanisms secure the traversingmechanism.

(2) (a) Elevating and traversing the weapon are accomplished byelevating and traversing handwheels.(b) Stops are provided to control maximum elevation, depression,and traverse. Trails are spread 900 for maximum traverse. Whenspread 45 the traverse is controlled by a stop on the traversingmechanism.(3) When firing with the trails locked together the firing jackis not to be manipulated to support the carriage weight, as a three-

point support is necessary and consists of the two wheels at thefront and the spade end of the trails at the rear. However, underthis condition care must be exercised to insure that the total traversedoes not exceed 520 mils or the elevation exceed 380 mils.(4) When the carriage is emplaced with the trails spread, thefiring jack will be used to form a three-point support, consistingof the jack and the spades. However, on level ground the piecemay be fired safely from the wheels with the trails in either of thespread positions.(5) Height of the jack is immaterial if it is such as to raise thewheels. On soft ground the jack may sink. It may therefore benecessary to jack up the carriage from time to time. The trailswhen spread for firing have two symmetrical positions. If neces-sary, however, one trail may be spread 45 and the other 221/20, ifthe site has obstructions to prevent spreading both trails to the221/2 or 45 positions.(6) The recoil mechanism for this carriage is that of the 75-mmgun carriage, M1897 (French), modified by removing the elevatingmechanism and mounting in a cradle in order to move axis of ele-vation of the gun to the rear, thereby attaining a greater maximumelevation (fig. 18).(7) The cradle is of built-up steel construction. The recoilmechanism is assembled to the cradle by trunnions seated in bearingsat the rear of the cradle. Rear of the recoil mechanism is supportedon brackets and secured by studs.d. M2AS.-(l) The carriage, M2A3 (figs. 33 and 34), is a modi-fication of the 75-mm gun carriage, M2 (fig. 27). This modificationconsists of the following changes:(a) Firing jack is eliminated and the carriage is equipped witha pivoted axle which automatically adjusts itself to permit layingthe piece with the wheels at an angle up to 10 to the horizontal.

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(b) Top carriage modification consists of removing and relocatingof various pads, brackets, and bosses and adding other parts to mount-ing and elevating mechanism handwheel on the left hand side of thecarriage, and to provide for cradle and traveling locks. The lowerpart of the top carriage is modified to provide clearance for thepivoted axle.

(e) Trails and spades are modified by reducing the length 19 inches.The drawbar is designed for use with a motorized unit.(2) The recoil mechanism, T7, combines the cradle, recoil, and re-cuperator (counterrecoil) cylinders. Its function is to check move-ment of recoiling mass in recoil and counterrecoil in a gradualmanner so as not to cause displacement of the carriage.(3) Other characteristics of the M2A3 carriage are similar to theM2A1 and M2A2 carriages and for detailed information regardingthese characteristics reference should be made to these carriages asset forth in this manual.

(4) The gun mounted on the M2A3 carriage is the M1897A4(fig. 6).

10. Operation of carriages.-a. M1897, M1897MIA2, andM1897A4.-(1) To elevate.-Elevating crank is on right side of car-riage. To elevate, the crank is turned counterclockwise; to depress,it is turned in the opposite direction. One complete turn of elevatingcrank (figs. 9 and 15) elevates or depresses gun and cradle 8 mils.Limitations of the carriage allow 213 mils (12 ) elevation and 0 mils(0 ) depression of cradle.(2) To set angle of site.-Angle of site handwheel (figs. 11 and 16)is located on left side of carriage. Release the angle of site hand-wheel by means of the angle of site handwheel latch handle. Clock-wise movement elevates and counterclockwise depresses. One com-plete turn of the handwheel in one or the other direction elevates ordepresses the gun 16 mils.

(3) To traverse.-Traversing handwheel (figs. 11 and 16) is onleft side. Clockwise rotation of handwheel traverses carriage to leftand counterclockwise to right. One turn of handwheel traverses car-riage 1.8 mils. Limitations of the carriage allow traverse of 53 mils(30) right and 53 mils (3) left.

(4) To place M1897 or M1897MIA2 carriagein abatage.-Toplacein firing position on brake frame, place a man on each side of the trail(fig. 10). Each man grasps a tie rod at the end nearest the right brakebeam, lifting it up as far as it will go. Brake latch pin in rightbrake shaft lever is lifted out of engagement with the lug on the rightseat support, and brake shaft levers are pulled back from under brake

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TM 9-30575-MM GUN MATERIEL, M1897, AND MOI)IFICATIONS 10

beam crank tubes, allowing lower end of brake beam frame with itsbrake shoes to fall to the ground behind the wheels. Lift rear of trailapproximately 3 feet from the ground and pull back on trail. Lowertrail, so that the carriage rotates about the spades, and wheels rollback onto brake shoes (fig. 17).

(5) To remove M1897 or M11897MIA2 carriage from abatage.-Reverse operations in (4) above.

b. M2A2.-(1) Elevation.-Elevating handwheel (fig. 26) is lo-cated on right side of top carriage. Stops control elevation anddepression.

(2) T'raverse.-Traversing handwheel (figs. 25 and 27) is locatedon left side. Traverse depends upon the spread of the trails. Whentrails are spread to the limit and locked the gun may be traversed 85 .When trails are spread 45, traverse is limited by a stop on the travers-ing mechanism to 45 .

(3) Firing to traveling position.-To change from firing to travel-ing position it is necessary to release the firing jack (figs. 21 and 27).This is accomplished by placing right handspike part way into itssocket (fig. 21). Raise jack sufficiently to release tension on the shotbolt. Withdraw shot bolt with left hand and secure it in its dis-engaged position. Standing clear of the gun barrel, quickly pull outhandspike from its socket.

(a) Disengage firing jack from axle by pressing on the jackrelease pedal (fig. 21). Then swing firing jack up and toward themuzzle of the gun and manipulate the cradle by means of the elevat-ing and traversing handwheels until arm of firing jack enters itsseat on cradle and is locked in place by cradle lock pin (fig. 24).Rotate cradle lock pin handle 90 upward, then seat and secure it bythe turnbuckle. Secure traveling lock located on left of top carriageby rotating it to its rearward position.

(b) Withdraw trail lock pins. Close trails and lock them to-gether by means of trail connection hook handle (fig. 31).

(c) Turn drawbar downward and lock in this position by meansof drawbar lock shaft.

(d) Mount accessories to trails and release wheel brakes.(4) Traveling to firing position.-To change from traveling to

firing position reverse the operations previously described. In orderto jack up carriage insert both handspikes in firing jack sockets withbent ends of ratchet plunger pins to the outside, and operate hand-spikes alternately. Insure that spring plunger knob is correctly setto control maximum traverse for the selected trail spread.

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11-12recoil mechanism not authorized, nor do any filing on the sights orgun parts other than outlined, and only by order of the batterycommander.

d. Use of wrenches which do not fit snugly on any part should beavoided. They will only fail and will damage the corners of thenuts or bolt heads. Also there is danger of spreading the wrenchesand rendering them useless.

e. In assembling, assembly of subassemblies should be completedbefore attempting to assemble the larger ones in which the sub-assemblies are placed. In all assembling, bearings, sliding surfaces,threads, etc., should be cleaned and lubricated.

12. Disassembly of breech mechanism and breechblock.-a.Breech mechanism.-(1) With breech closed and locked, releasebreechblock stop (fig. 7) by turning breechblock stop pin until itcan be pulled upward through keyway in the stop. After this oper-ation, swing the stop outward which releases extractor spindle. Pullextractor spindle to left until extractor tang is released.

(2) Remove extractor tang (fig. 7) through the loading hole inthe breechblock. Push extractor spindle back into its seat andraise the curved end into the lug so that it will be out of the way.

(3) Release breechblock latch from latch catch by pushing inon operating handle plunger. Unscrew breechblock from breechrecess by turning counterclockwise. It should be grasped firmly afterunscrewing it six turns from closed position as it will drop out be-tween the sixth and seventh turns. To protect it from the dirt, placebreechblock on a bench or paulin before attempting further dis-assembly.(4) Withdraw extractor spindle (fig. 7) and remove extractor.

(5) For views of component parts of breech mechanism see fig-ure 8.b. Breechblock.-(1) Remove safety piece assembly and firing pin(fig. 7) by drawing firing hammer to rear, pulling safety piece

plunger knob outward, unscrewing safety piece.(2) After the firing safety piece assembly and firing pin are

removed, press firing hammer assembly as far as it will go intosafety piece recess, remove firing hammer pin, then remove firinghammer.

(3) Remove lanyard from firing hammer link (fig. 7) by with-drawing it through eye of breechblock arm.(4) Remove firing rack assembly, firing rack spring, and firingrack spring assembling pin by pushing operating handle plungerforward and pressing inward on head of pin with a screw driver.

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TM 9-30512-14 ORDNANCE DEPARTMENTOne-fourth of a turn will disengage pin from slot in firing rackfrom which position it can be withdrawn.

(5) Remove breechblock latch assembly, breechblock latch spring,breechblock latch pin by turning it approximately one-quarter of aturn outward to disengage it from its retaining groove. Draw pinout of arm. Hold parts as spring forces them out. If spring doesnot come out force it by pushing pin through hole in breech faceof breechblock arm.(6) Remove operating handle plunger block, operating handleplunger and operating handle plunger screw by unscrewing latter andwithdrawing parts. If plunger block does not come out force it bypushing breechblock latch pin through small hole in operating handle.13. Removal of shields from carriage lV1897, ]1897MIA2,or 1VM1897A4.-a. To remove right shield.-(1) Set carriage at 0traverse. Remove thong and drive out apron latchkey (figs. 36 and37) connecting shield staple and brake worm support. Disconnectshield brace by removing cotter pin and washer and withdrawingshield upper pin.(2) If shield is seven-piece type, remove thong and drive out keyconnecting right and left shields.

(3) If shield is four-piece type remove nut and drive out bolt con-necting the distance plate and the right shield, and swing distanceplate out of the way. Remove thong and drive out key which holdsapron in traveling position and swing apron down. Remove brakecrank pin and pull off brake crank. Pull right side of shield to tihefront until shield staple is free of brake worm support. Pull shieldto right and out of socket on trail side plate.

b. To remove left shield.-(1) Remove thong and drive out keyconnecting shield staple and left shield bracket.(2) According to the type of shield, proceed as provided above.Pull left side of shield to front until shield staple is free from shieldbracket, and pull shield to front.

14. Dismounting and mounting gun, carriage M1897,M1897MIA2, or M1897A4.-a. Dismowunting.-(1) Provide meansfor supporting the gun while it is being removed in order to avoiddamaging the upper roller path of the recoil mechanism by the frontrollers.

(2) Set brake.(3) Set gun at 0 elevation and see that it is in battery position.(4 ) With breechblock removed, raise piston rod coupler key latchand withdraw piston rod coupler key (fig. 17) from right to left asfar as it will go . In case it does not work freely, tap key lightly,

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TM 9-30575-MM GUN MATERIEL, M1897, AND MODIFICATIONS 14-16

care being taken not to injure latch. Remove sweeper bolt pin andsweeper plate guide bolt, and withdraw sweeper plate.

(5) Push the gun to the rear, with pairs of men at opposite endsof three heavy timbers supporting the gun at either end and at thecenter.b. Molnting.-Assemble in reverse order of dismounting.15. Dismounting and mounting recoil mechanism, carriage

M1897, M1897MIA2, or M1897A4.-a. Dismounting.-(1) Re-mnove screws and sight shield.

(2) To remove range rack screw, raise rear of rocker by turningangle of site handwheel until segment rack of rocker and angle of siteworm gear shaft pinion are out of mesh. Lift rear end of recoilmechanism as far as it will go. Remove cotter pin and elevatingscrew pin by turning handle of pin to about a horizontal position.This disengages the lug of the pin. Swing elevating screw towardrear, free of lugs of rocker, and unscrew from elevating nut. (Ifforce is necessary to remove elevating screw, care must be taken notto damage walls of opening through the screw.)(3) To remove range scale, turn elevating crank (fig. 15) untilrange scale reads zero. Drive out Crank locking plate pin and pullelevating crank locking plate off yoke. The locking plate bringswith it the elevating crank and crankshaft. Remove range scale shaftnut and range scale washer. Remove range scale.

(4) Open right and left trunnion caps by removing thongs anddriving out keys. Tap rear end of oil hole housing until it is pos-sible to pry the cap. Remove rocker arm caps by inserting a bronzedrift into oil hole. Lift it out.

(5) Raise recoil mechanism clear of trunnion bearings and moveit to rear and off carriage. Place mechanism on wood blocks.

b. Mounting.-Assemble in reverse order of dismounting.16. Disconnecting and connecting brake frame to axle, car-riages M1897 and M18971IA2.-a. To disconnect.-(1) Releasebrake. Shoes should be far away from tires. Remove cotter pinsfrom brake forks and brake fork keys. Pull up on keys and remove.(2) The next step requires a man on each side of the trail. Eachgrasps a tie rod at end nearest brake beam and lifts it up as faras it will go. The man on right side of trail uses his left handto hold tie rod, leaving his other free to turn brake latch pin whichengages lug on seat support bracket. He turns latch pin to rightand raises it as far as it will go and pulls backward on brake shaftlever. Drop brake frame on ground and pull backward.

b. To connect.-Assemble in reverse order of disconnection.15


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17. Removal and assembly of wheels, carriages M11897 and1V1897M1IA2.-a. Removal.-Jack up carriage until wheels are clearof the ground. Block up under front end of trail so as to preventcarriage from tipping or slipping. Withdraw thong from linchpinlatch (fig. 10) and swing latch out until it is free. Pull out latchand linchpin. Pull off axle caps.

b. Assembly.-Assemble in reverse order of removal.18. Removal and assembly of axle, carriages M1897 andM1897MIA2.-a. Removal.-Drive off left axle collar. Move axle

to the left by means of traversing mechanism until right axle collarcomes in contact with right axle bracket. Remove axle sleeve.(Should axle sleeve stick, traverse axle to the right when sleeve willremain in right axle bracket.) Traverse axle to the right untilthreads on axle and those in traversing nut are completely disengaged.Pull out axle to the right.

b. Assembly.-Assemble in reverse order of removal.19. Disassembly of gun and carriage, M1897A4.-Disas-

sembly of gun and carriage, with exception of the high speed adapter,is the same as that outlined for disassembly and assembly of the75-mm gun and carriage, M1897 and M1897MIA2.

20. Disassembly and assembly of high speed adapter, car-riage M1897A4.-a. To remove disk and rim wheel.-Wheels mustbe raised clear of the ground. Remove disk and rim wheel nuts(fig. 29) and then slip disk and rim wheel off.b. To remove hub and brake drum assembly from spindle.-Removehub cap and hub cap gasket. Remove cotter pin, nut, and wheelspindle outer washer from wheel spindle. Then slip hub and brake

assembly off the wheel spindle.c. To remove spindle bracket from axle.-First remove disk and

rim wheel as in a above. The hub and brake drum assembly mayalso be removed as in b above, though this is not necessary. Dis-connect radius rod from radius rod bolt stud. Remove seven hex-Igonal head cap screws which fasten brake shaft in left spindlebracket. Disconnect brake rods from brake shaft. Remove cotterpin and then remove linchpin assembly, axle cap, and high speedaxle bracket outer shim if one is used. Spindle bracket may then beslipped off axle.

d. To remove wishbone.-Remove ball socket outer cap from rearend of wishbone, then remove axle clips clamping wishbone to axle.Wishbone is then free.e. To remove seats.-Remove ball socket outer cap. Disconnect

each radius rod at one end. Then upon removing bolts the compen-16


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sator shaft, compensator shaft support, brackets, and right and leftseat and support assemblies can be removed from trail.

21. Dismounting and mounting gun, carriage M2A2.-a.Dismounting.-(1) Provide means for supporting gun in a horizontalposition while it is being removed in order to avoid damage to gunslides.

(2) With trail spread, place piece on the firing jack, or if left on itswheels, set brake. Depress gun until equilibrator assembling nuts(fig. 23) can be screwed on to equilibrator rod their full length.Elevate gun to 0 elevation and see that gun is completely in battery.

(3) Remove breechblock assembly. Raise piston rod coupler keylatch and withdraw key. In case it does not work freely, tap keylightly, care being taken not to injure latch.(4) Push back gun. When removing gun do not cramp it. Placegun upon wood blocks or some suitable rest.

b. Mounting.-(1) Reverse procedure of a above, then elevate anddepress piece to be sure of ease of operation.

(2) Assemble breechblock. Lock gun to recoil mechanism by assem-bling piston rod coupler key.

(3) Depress gun and remove equilibrator assembling nuts (acces-sory) (fig. 23). Equilibrator trunnion pins must be seated properly intheir bearings. Elevate and depress tipping parts to be sure of ease ofoperation.

22. Dismounting and mounting recoil mechanism, carriageM2A2.-a. Dismounting.-(1) Remove telescope mount and rangequadrant. Proceed according to instructions outlined in paragraph21a. With screw driver, loosen machine screw (fig. 22) in trunnionnut and remove nut. Remove machine screws in trunnion ball retainer.Remove bolts (fig. 27) in trunnion caps, and remove caps. Raise hold-ing cradle and recoil mechanism sufficiently to slide retainer (fig. 22)trunnion bearing plate, outer, trunnion ball cup, trunnion ball, andtrunnion ball spacer from holding cradle trunnions.

(2) In removing parts referred to care must be taken not to bur orbruise them. They should be cleaned and stored in a safe place untilreassembled. Inner bearing plate, inner trunnion ball retainer, andtrunnion bushing should not be removed.

(3) Lift holding cradle and recoil mechanism clear of top carriagetrunnion bearings. Place mechanism on wood blocks.

NOTE.-Each holding cradle and recoil mechanism is considered a unit andmnust be shipped and handled as such since location of studs which secure recoilmechanism to cradle are in a different position on each recoil mechanism.

2:)5667( 1-41 2 17


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TI 9-30522-25 ORDNANCE DEPARTMENT

b. Mournting.-(1) Lift holding cradle and recoil mechanism intoposition, trunnions of cradle being in line with trunnion bearings oftop carriage, and with sufficient clearance to assemble the trunnions.

(2) Clean trunnion bushings (fig. 22) and coat them lightly withmedium mineral lubricating grease. Assemble the following parts inthe order given: Trunnion ball, trunnion ball cup, trunnion ballspacer, trunnion bearing plate, outer, and trunnion ball retainer, outer,coating each part with grease.(3 ) Lower cradle and recoil mechanism into top carriage trunnionbearings. Assemble trunnion caps with bolts (fig. 27). Line up screwhole in trunnion ball retainers, inner (fig. 12) and outer, and trunnionbearing plates, inner and outer, trumlion caps and top carriage trun-nion bearings, and assemble machine screws. Screw trunnion nuts oncradle trunnions and lock in position by tightening machine screws.Replace telescope mount and range quadrant.

23. Dismounting and mounting equilibrator, carriageM2A2.-a. Dismounting.-(1) Place carriage in firing position.Depress gun until equilibrator assembling nuts (accessory) (fig. 23)can be screwed on to equilibrator rods their full length, using socketwrench.

(2) Elevate gun, then raise and withdraw equilibrator throughrear opening of top carriage.NoTE.-The equilibrator trunnioln pin may be adjusted or removed by first

releasing the equilibrator trunnion pin lock. Further disassembly of theequilibrator by the using arm is prohibited.b. Mounting.-Elevate gun and insert ball portion of equilibrator(fig. 23) into its seat. Assemble equilibrator trunnion pin, making

proper adjustment by screwing pin in or out. Depress gun untilequilibrator trunnion pin is properly seated. Assemble equilibratortrunnion pin lock.

24. Disassembly of wheel hub from spindle, carriageMV2A2.-Remove machine screws from hub cap. Remove cotter pinfrom wheel spindle. Remove slotted nut and disk and rim wheelspindle washer. When pulling hub from spindle be sure to protectroller bearing from falling to the ground.

25. Assembly of wheel, carriage M2A2.-a. If hub is removedfrom spindle the cavity of hub should be cleaned with dry-cleaningsolvent and wiped dry. Fresh grease should be packed aroundroller bearings before assembly.

b. Slide hub over spindle, guiding cup of inner roller bearing overcone and rollers and brake drum. Slide outer cone and roller ofbearings on spindles and guide them into their seats in roller bearing

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75-MM GUN MATERIEL, M1897, AND MODIFICATIONScups. Assemble disk and rim wheel spindle washers, outer, andslotted nuts on spindles. Tighten nuts sufficiently to allow wheels torevolve freely without end play. Assemble cotter pins. Attachhub caps with machine screws.

SECTION IVINSPECTION AND ADJUSTMENT

ParagraphGun - ..---- -- . . - - - - -- . - -- - - -- - - -- - - --.._ 26Carriage ...........-----_- - - - - ---------------..... 27Sighting equipment_ . _- - - - - - - - -- _ -- -- --- ------- 28

26. Gun.-The following instructions should be scrupulouslyobserved:Parts to be inspected in order

of iispe)ction Points to observea. Gun. a. Note general appearance, smoothnessof operation of breech mechanism in open-ing and closing, action of operating han-dle plunger and firing mechanism withlanyard. Note condition of bore for cop-per deposits on lands and in grooves, anderosion at origin of rifling. Examinebreech recess for scored and bruisedthreads and leveling plates for burs orother defects. Examine gun slide bear-ings or rollers for burs, dents, cleanliness,proper lubrication, and rigidity of theassembly. The bronze slides of theM1897A4 gun should fit the rails tightly,but the rails should be able to move longi-tudinally from their anchor at the jacketsupport. Insure that barrel supports andjacket and muzzle hoops are tight. Ex-amine safety bolt assembly for deformedlug and for condition of the spring.

b. Breech mechanism. b. Disassemble and clean breech mech-anism. Examine breechblock for any de-fects, also firing pin. Examine firinghammer and firing rack for burs orbruises. Test action of firing rack springby pulling lanyard. Note striking forceof firing hammer.

19

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TM 9-30526-27 ORDNANCE DEPARTMENTParts to be inspected in order

of inspectionc. Extractor tang.d. Extractor spindle.e. Extractor.f. Safety piece.g. Firing pin.A. Firing hammer.i. Firing rack spring

assembling pin.j. Firing rack.k. Firing rack spring.1. Breechblock latch pin.in. Breechblock latch.n. Breechblock 1a t c h

spring.o. Operating h a n d I e

plunger screw.p. Operating h a n d 1 eblock.

q. Operating h a n d 1 eplunger.

27. Carriage.a. Carriage.

b. Recoil mechanism.

Points to observec. Note deformation or breakage.d. Note evidence of scoring or binding.e. Check for broken lips, scoring or

binding.f. Bruised threads or deformed ham-mer stop screw.

q. Deformed point. protrusion.A. Deformed gear teeth.i. Deformed projections.j. Condition of teeth and screw.A. Weakness or breakage.1. Binding or breakage.77 . WVear or breakage, worn pawl, weak

or broken pawl spring.n. Weakness or breakage.o. Condition of threads.p. Worn or broken projections.q. Condition of threads and scores on

exterior.a. General appearance. Note condition

of carriage paint, and that all movingparts are lubricated.

b1. Release reserve oil in recuperator.Note action of oil indicator and whetherit recedes. Replenish oil reserve and seethat oil indicator moves out as oil isforced into recuperator. Examine frontend of recoil cylinder, filling and drainplug hole, and oil index recess for leak-age. Presence of a few drops of oil inany of these places will in no way affectthe recoil mechanism. When any undueleakage is present the use of the recoilmechanism is prohibited. Return to ord-nance personnel for repair.

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75-MM GUN MATERIEL, M1897, AND MODIFICATIONSParts to be inspected in order

of inspectionc. Elevating mechanism.

d. Angle of site mech-anism, carriages M1897.M1897MIA2, and M1897-A4.

e. Traversing mechan-ism.. B r a k e mechanism,

carriages M1897A2 andM1897MIA2.

g. Shield.

A. Trail.i. Wheels, steel-tired,

carriages M1897 andM1897MIA2.

Points to observec. Elevate and depress the gun the full

extent of travel. Note binding or unduebacklash.d. Elevate and depress rocker throughfull extent of travel. Note any unduebinding or backlash.

e. Traverse carriage. Note smooth-ness of operation, binding, or backlash.i. See that brakes operate freely.(1) Try the wheel brakes by jackingup carriage and standing on a spoke.

Neither wheel should revolve.(2) Lower brake mechanism to firing

position and test carriage as to whetherit may be traversed from extreme rightto left without opposition from brakeframe.

(3) Latch brake mechanism and testlatches.q. Examine shield, and note whether

all keys, thongs, hinges, etc., are in serv-iceable condition.h. Loose rivets, nuts, and screws.i. Test tightness by tapping lightly

with a hammer.(1) Tightness of hub bolts.(2) End play by grasping spokes andmoving wheel in and out.(3) Remove wheel and note condition

of inner and outer washers. Note condi-tion of hub liner, spindles, and exposedparts of axle.

(4) Replace wheel and take up endplay; make certain that leather washer inaxle collar is not less than 1/s inch thick.(5) Pull out on top and push in onbottom of wheel. Hold wheel in this po-sition and place a scale or straightedgeon shield with its end touching inner edge

21

TM 9-30527


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TXM 9-30527 ORDNANCE DEPARTMENT

Paris to be inspected in orderof inspection

j. B r a k e mechanism,carriages M1897A4 andM2A2.

k. Trails, split (75-numgun carriage M2A2).

I. Wheels and tires oncarriages M1897A4 andM2A2.

,a,. Wheel, disk and rim,with tire, assembly (75-mm gun carriagesM1897A4 and M2A2).

Points to observeof top of tire. Then push in on top andpull out on bottom of wheel. The dis-tance between end of scale and inneredge of the top of the tire represents therock of the wheel on the axle. The max-imum allowable rock is 0.281 (%2) inch,representing an increase in diameter ofhub liner of 0.06 inch. When hub lineris beyond this limit is must be replaced.

j. Test brakes by placing carriage infiring position, wheels clear of the ground.Set brake hand levers. Note position ofbrake ratchet pawl. If in last tooth ofbrake ratchet brake shoes should be ad-justed. Release brake hand lever to "oilff"position. Note whether wheels revolvefreely.

k. Place carriage in position. Movetrails to 45 position. Note that theyswing freely. Examine trail connectionSee that it locks the trails together with-out unnecessary strain.

(1) Test drawbar lock. Note whetherdrawbar lock shaft enters hole in drawbararm without force.

(2 ) Examine all supports and fasten-ings.

1. Examine nuts. Note condition andwhether they are set up tight. Notewhether rim is deformed.

m. Test wheels to see that they haveproper toe-in of 1/s of an inch and re-volve freely and that there is no wobble.If wheels wobble examine spindles to seethat they are not bent. Examine wheelsfor warping. Examine tires to seewhether crown of tire is taking the wear.If worn to left or right of crown testalinement of wheels.

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75-MM GUN MATERIEL, M1897, AND MODIFICATIONSParts to be inspected in order

of inspectionn. Traveling lock of

M2A2 carriage.o. Traversing rack ofM2A2 carriage.

28. Sighting equip-ment.a. General.

b. Telescope mount.

c. Panoramic telescope.d. Range quadrant.

Points to observen. Examine for performance of itsfunction.o. Examine traversing rack for brokenor deformed teeth.

a. Inspect for general appearance andlubrication. Note undue lost motion inoperation of various gears. Check levelvials to insure that they are tightly se-cured in their holders.b. Insure that all parts are properly as-sembled and that various screws and studsare tight. Check the ease of operationfor travel and for firing. Inspect aline-ment and if necessary adjust telescopemount. Check lubrication.

c. Check lubrication. Inspect aline-ment and if necessary adjust.d. Check lubrication. Inspect aline-ment and if necessary adjust.

SECTON VMALFUNCTIONS

Gun -------......- -Recoil mechanism -------------------..--- -------

29. Gun.Malfunction Cause

a. No momentum a. B ro k e n firingof firing hammer. rack spring.

b. Fails to fire b. Firing rack anduntil after several hammer not workingpercussions on freely.primer.

Paragraph-_________-- --.. 29

.... -................0

Correctiona. Replace.b. Disassemble firing

mechanism completelyand examine all partsfor burs or roughenedsurfaces. Remove bursor rough spots with finefile or oilstone. Washall parts with dry-clean-ing solvent. Dry thor-

23

TM 9-30527-29


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JMalfunction

c. Fails to dis-charge; no percus-sion on primer.

d. Fails to extractcartridge case.

e. Pawl fails tooperate.

f. Breechblockdoes not rotatefreely.

Cause

(1) Weak firingrack spring.

(2) Deformed orbroken firing pinpoint.c. (1) S a f etypiece not locked.

(2) Breechblocknot fully closed.(1. Broken extrac-tor.

e. Broken p a w lspring or brokenbreechblock 1a t c hspring.

f. (1) Lack oflubrication.

Correctionoughly a n d lubricatewith o i l, lubricating,SAE 20, Navy Symbol3050 or 1047.(1) Replace.

(2) Replace.

c. (1) Set safetypiece plunger properlyin breechblock arm.

(2) Close breech-block.d. Ram the case outgently from the muzzleend. Examine edge ofchamber for defor-miation or burs whichmight cause difficult ex-traction. Disassemblemechanism and replaceextractor if necessary.e. Disassemble breechmechanism until pawlcan be removed. Ex-amine springs and iflatch spring is brokenreplace it. If p a wlspring is broken, replacewith new breechblocklatch assembly.

f. (1) Remove breech-block. Clean block thor-oughly and recess withdry-cleaning s o 1v e n t.Wipe thoroughly dry.Lubricate with oil, lu-bricating, SAE 20, NavySymbol 3050 or 1047,and assemble.

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75-MM GUN MATERIEL, M1897 AND MODIFICATIONSCause(2 ) Burs or rough-

ness on threads ofbreechblock or inbreech recess.

g. Safety bolt can 9. Ibe pushed down by Weakhand after piston springrod coupler key is in notremoved.h. Safety bolt h. Ifails to rise.

i. Safety bolt does i. Vnot remain in upper springposition when cou- not eipler key is with-drawn.

30. Recoil mechanism.Malfunctiona. Oil leaking into a. Ifront of recoil cylin- ton p

der. of cy]b. Oil leaking into b. Ifilling and d r a i n ing vplug recess.c. Oil leaking c. Iaround oil index. ing.d. Oil index not d.functioning.

e. Failure of gun e. ]to return into bat- reseritery.

Broken spring.spring or

g not engagingtch.Broken lug.Veak or brokeng. Spring doesngage in notch.

Correction(2) Remove breech-block and clean blockand recess as in (1). Ifburs or roughness arefound, correction mustbe made by ordnancepersonnel.

g. Replace with newsafety bolt assembly orrefer to ordnance per-sonnel.h. Replace safety bolt

assembly.i. Replace safety bolt

assembly.

Cause CFailure of pis- a. N otacking or wear personnel.linder wall.Failure of fill-alve.Failure of pack-Index stuck.

Insufficient oilve.

Iorrectioni f y ordnance

b. N o t i fy ordnancepersonnel.

c. N o t i f y ordnancepersonnel.d. Withdraw reserveoil and insert approxi-mately one-half the ca-pacity of the oil screwfiller. Tap oil indexlightly as oil is beingadded.e. Withdraw reserveoil; insert sufficient oil tobring oil index even withrear face of cylinder rearsealing plate.

25

JlIalfunction

TM 9-30529-30


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Malfunction

f. Return of guninto battery with ashock.

Cause(1) Low nitrogen

gas pressure.(2) Excessivefriction.(3) Damaged

slides, piston rod, orpiston.f. (1) Too muchreserve oil.

(2) Air from re-coil cylinder escap-ing too fast throughrespirator.

Correction(1) Notify ordnance

personnel.(2) Notify ordnancepersonnel.(3) Notify ordnance

personnel./. (1) Withdraw re-

serve oil. Insert suffi-cient oil to bring oil in-dex even with rear faceof cylinder rear sealingplate.

(2) Adjust respiratorto small air vent. If thisfails to correct trouble,withdraw oil reserve asindicated in (1).

SECTION VICARE AND PRESERVATION

G u n ------ - -- ----------------------Carriage - . . .....___.-_____ .-Recoil mechanism -----------------Recoil oil --- - --- _ -------------High speed adapter --------.-------Brake mechanism, carriage M2A2___Lubrication instructions -----------Cleaners and abrasives ---- .----Preservatives ------------------- ---Paint and related materials --- ----Lubricants ...............--..---.Miscellaneous materials and tools ---

Paragraph.-__. . ..................1

______..._______..___..__ 32-.-- _--___.-__ -_-_________ 33_______...___.._________ 34.--. .......................5- - - - -- - - - -- - - - - - - - - - - -- - - 36

......- . ............_ _- 37

..................-- --_.. 38.............--- . ..........39.-. _____________--_______ 4(0................-- ........ 41.. -______________--______ 42

31. Gun.-a. General.-(1) It is important that whenever therate of fire permits, the cannoneer look through the bore beforeeach loading to ascertain whether or not particles of cartridge case,wadding, or unburned powder remain in the bore. Presence of suchparticles may cause damage to the piece. During night firing thesponge should be used between rounds.

(2) If enemy shell burst near the gun, be sure before firing thatthe gun has not been damaged to a dangerous degree. Damage of aserious nature should be reported to the ordnance officer.

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75-MM GUN MIATERIEL, M1 897, AND MODIFICATIONS(3) In cleaning after firing, wash bore with a solution of 1/2 pound

of soda ash or 1 pound of sal soda in 1 gallon of water. Use a pieceof burlap or cleaning cloth around the metal end of the rammer stafffor swabbing. When all powder fouling has been removed, swab borewith clear water and finally dry bore with a piece of clean burlapor cleaning cloth.

(4) Leveling plates should be protected. Tools or other articleswill not be placed upon them. In case of injury repair must be madeby ordnance personnel.

(5) In order to clean oil well, muzzle rollers, and covers, the rollerside plates of the M1897 gun (fig. 5) should be removed. Removethem by unscrewing muzzle roller center screw.

(6) Slides of the M1897A4 gun (fig. 6) should be examined bypushing the gun to the rear until three-quarters of the bearing strips,left and right, are exposed. Burs or rough spots should be removedwith a fine file. Wash the strips with dry-cleaning solvent and wipedry. Coat the strips with oil, lubricating, SAE 20, Navy Symbol3050 or 1047, and push gun into battery. Periodically, the gunshould be removed from the carriage in order to clean the entirelength of the slides.

(7) Lubricating instructions are given in paragraph 37.(8) When mat6riel is not in use covers must be used.(9) When gun is not to be used for a considerable time the bore,

breech mechanism, and bright and unpainted surfaces should becleaned with dry-cleaning solvent and surfaces coated with rust-preventive compound.

b. Breech mechanism.-(1) Should be kept clean and parts welllubricated. When not in use disassemble periodically, especially fordetection of rust. When in use disassemble frequently, clean and oil.It should be so cared for immediately after firing.(2) In removing rust-preventive compound the greater partshould be scraped off. That remaining should be removed with dry-cleaning solvent used on a rag or waste.

(3) A steel hammer must not be used directly on any part of themechanism. A copper drift or a hardwood block should be inter-posed, or a copper hammer used.

(4) Vigilance must be exercised to detect any cutting or abrasionson the pressure side of the threads of breechblock and breech recess.If breechblock does not rotate smoothly or if it requires a greatereffort than usual to operate, it should be disassembled and examined.Scoring or bruises on threads of breechblock or breech recess shouldbe reported to ordnance personnel.

27

TM 9-30531


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TX 9-30531-32 ORDNANCE DEPARTMENT

c. Firing meehanism.-(1) The parts require the same attention asthe breech mechanism. Therefore, frequent disassembly for thepurpose of cleaning and oiling is required.

(2) Fouling of the firing pin, or the use of a thicker oil than author-ized will cause absorption of the energy of the firing rack spring andfiring hammer and may result in misfire. This is especially true incold weather.

(3) Wear in this mechanism is negligible. Deformation may be onthe rear end of the firing pin. This wear may cause sticking in thesafety piece. If the firing pin is examined after each firing, replace-ment can be anticipated.

32. Carriage.-a. Attention should be given to cleaning, lubrica-tion, and loose or broken parts. Lubrication, with method and fre-quency of application, is covered in detail in paragraph 37.

b. Bearing surfaces, revolving parts, springs, gear teeth, brakemechanisms, screw threads, and exterior parts, must be clean and freefrom dirt. Special attention should be given to exposed gear teethand bearing surfaces. In disassembling and assembling operations,precautions must be taken to prevent entrance of foreign matter.

c. (1) Wheels pertaining to the M1897 and M1897MIA2 carriagesshould be removed periodically for examination and cleaning of axle,axle collars and washers, axle caps and washers, linchpins, and hubboxes. Roughness due to scoring or cutting should be smoothed off.

(2) Nuts on hub bolts should be tightened frequently during thefirst year, and at least twice a year thereafter. Ends of bolts arelightly peened over. Wooden parts are made of seasoned materialand hub bolts are properly tightened, but in time the wood dries andshrinks and the spokes become loose. If used in this condition wheelsmay become damaged, unfit for service. Wheels should not be soakedin water to tighten tires by expanding the wooden rims.

(3) Axle caps allow three adjustments before it is necessary to addwashers. Leather washers should be placed between outer end of huband axle cap so that after the linchpin is in place the wheel has onlya slight longitudinal play. There should be at least one leather washerbetween hub and axle collar. Axle caps are notched, therefore effortshould be made to obtain the above results with the deepest notch inaxle caps. Reduce the longitudinal play by placing linchpins inshallow notches.d. Carriage should be given a general inspection periodically.

e. Care and maintenance of the carriage require the use of thecleaning and preserving materials issued by the Ordnance Department.

J. When carriage is stored or is to remain unused for a considerable28


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TM 9-30575-1MM1 GUN MATthRIEL, M1 89 AND MODIFICATIONS 32-33

length of time, all bright and unpainted surfaces should be protectedwith a coat of rust-preventive compound. Before applying the com-pound the surfaces should be cleaned with dry-cleaning solvent.

33. Recoil mechanism.-a. Firingprecautions.-(1) Before fir-ing, examine for leakage of oil, oil reserve, and see that front ofrecoil cylinder is clean. Holes in respirator must not be clogged.Slide and roller paths of the cradle must be clean and properlylubricated.

(2) During firing, action of the mechanism should be noted, andthe following operations checked:

(a) Gun recoils its prescribed distance.(b) Gun returns into battery without shock.(c) Leakage of oil from filling and drain hole, oil index recess,

and front of recoil cylinder is not excessive.b. Oil.-(1) General.-When carriages are to travel or to be used

at drill, recoil mechanisms will be filled to create an excess reserve ofoil as described in (3) (c) below. An excess reserve of oil has beenfound necessary due to contraction of the oil which permits the gunto slide to rear sufficiently to bring rollers on roller paths, therebyindenting them. Care should be taken to establish normal reservebefore firing.(2) Leakage.-The following should be examined for oil leakage:front of recoil cylinder, filling and drain plug hole, and oil indexrecess.

(3) Reserve.-Firing should not be undertaken with an excess orlack of reserve oil. The oil reserve is indicated by position of theoil index with reference to rear face of recuperator cylinder rearsealing plate, as follows:

(a) None, indicator is well into recess.(b) Full, end of index is even with rear face of recuperator cylin-der rear sealing plate.

(e) Excess, index projects beyond rear face of cylinder rear sealingplate.c. To reduce or exhaust oil reserve.-(1) Remove the filling and

drain plug.(2) Screw in the filling and drain valve release.(3) Oil flows out through release.(4) Unscrew release as soon as indicator begins to recede. If itis desired to eliminate the reserve completely, wait until flow stops.d. To replenish oil reserve.-(1) Use oil screw filler.(2) Inject oil, watch oil indicator, and stop injecting oil when

indicator reaches rear face of recuperator cylinder rear sealing plate.29


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TM 9-30533 ORDNANCE DEPARTMENTe. To attach oil screw flller.-(1) Remove filling and drain plug.(2) Unscrew piston as far as possible. Unscrew nut. Remove

cover from filler. Fill filler with oil to within 1 inch of top, holdingfinger over nozzle.(3) Insert piston and tighten nut.

(4) Give a few turns to screw, holding nozzle upward so as toremove air. This is indicated when there are no bubbles.

(5) Screw filler into filling and drain plug hole. Care should betaken to hold the filler straight so as to engage the threads. Give afew turns to screw so as to force out any air.

(6) Screw in the piston of the filler.(7) Watch oil index and stop injecting oil when it reaches the rearface of the recuperator cylinder rear sealing plate. About one-half

the capacity of the oil screw filler is required.NOTE.-Care must be taken to avoid breaking end of filler or damaging threads

in filling and drain plug hole. Trouble is caused by attempting to operate theoil screw filler with one hand. In operating the filler the handle should beso that it projects an equal distance on either side of the screw, both handsbeing used. With this method of operation the filler can be operated success-fully and without damage.

f. To remove oil scretw flller.--(1) Unscrew filler.(2) Empty and put on nozzle cover.(3) Replace filling and drain plug.g. Nonfunctioning of oil index.-(1) Sometimes the oil index does

not register when oil is being injected. On this account an excessiveamount of oil may be injected.

(2) An excessive amount of oil is dangerous as during recoil thecontrol rod will jam. This will damage or may cause destruction ofthe recoil mechanism.

(3) If the oil index does not move in when oil is being extractedor if it does not move out when oil is being injected, it is probablethat the packing around the oil index is too tight. On the otherhand the index may be broken or frozen.(4) In order to test the oil index, by means of the filling and drainvalve release, drain all the oil that will run out. After removingfilling and drain valve release, inject oil by means of the oil screwfiller. While injecting oil, tap index lightly on each turn of the oilscrew filler. If index does not move out after about half the capacityof the oil screw filler has been injected, it is an indication that thereis something wrong with the mechanism and the ordnance officershould be notified. If index works properly after the operation de-scribed the reserve oil supply should be injected and drained off aboutthree times to insure that index is in working condition.

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(2) The following should also be observed:(a) Recoil oils should not be left in open containers nor subjectedto excessive heat.(b) Greatest care must be taken with recoil oils to exclude moistureand dirt.(c) Strain through clean cloth before inserting in recoil mechanism.(d) Do not mix recoil oils with any other type of oil.35. High speed adapter.-a. (1) As brake linings wear, it isnecessary to adjust brakes in order that brake linings may come incontact with brake drums. Adjustment is made by the brake ad-justing wedge being turned to the right one or two notches. After

adjustment, wheel should revolve without drag.(2) Carriage should be jacked up periodically and wheels re-volved. Wheels should turn freely with no excessive side play. Todetermine side play, grasp sides of tire and shake wheel back andforth. If there is excessive side play remove hub cap and cotter pinfrom spindle and tighten spindle nut until side play is removed.Reassemble cotter pin and hub cap.b. Carriage should not be moved any great distance with tirespartially inflated, as side walls are unduly bent and fabric is sub-jected to stresses which cause rim cutting. Test tires daily. Thoseon the M1897A4 carriage should be inflated to 25 pounds pressure,and those on the M2A2 carriage should be inflated to 30 poundspressure.c. Screws, bolts, and nuts should be tested once a week and set uptight. Lock washers should be examined and replaced if necessary.d. (1) Grease fittings of the adapter should be washed and cleanedin dry-cleaning solvent at least semiannually; also when the carriagehas had hard usage. Grease should be injected once a month into allbearings.(2) Wishbone should be lowered from the axle collars once a yearand then raised to see that it has maintained its alinement with thegrooves in the axle collars.(3) Ball socket inner and outer caps should be removed periodi-cally and examined for defects. Compensator ball stud spring shouldbe replaced if found to be weak or rusted.(4) Radius rod group should be disassembled periodically andcleaned to remove foreign matter that may have collected. Whenreassembling the parts should be lubricated.(5) Wheels, hubs, and brake drums should be removed after every1,000 miles. All grease should be removed from hub cavities, andhub and inner and outer roller bearings washed with dry-cleaning

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35-37solvent. When assembling, ball bearings must be packed with wheelbearing grease.36. Brake mechanism, carriage 1V2A2.-a. Functioning of thebrake is of vital importance. A freely operating brake insures alonger period of operation before readjustment becomes necessary.b. Brake adjustment is accomplished by rotating the brake shoeadjusting wedge (fig. 35) in the desired direction. The wedge ex-tends to the outside of the brake housing plate. The end of theadjusting wedge on which a wrench may be used is square.c. (1) Procedure for adjusting brakes is-

(a) Set hand brake lever at full released position.(b) Jack up wheel.(c) Adjust brake adjusting wedge until a drag is felt on wheel.Back off just enough so that there is no drag. Brakes must be coldwhen making this adjustment.(2) Position of hand brake lever and toe of brake shoe can beadjusted as follows:(a) Remove disk-and-rim wheel hub and brake drum.(b) Loosen locking nut at bottom of hand brake lever.(c) Drive out brake cam shaft sufficiently to permit its splined

section to rotate free of brake lever.(d) Rotate brake cam the desired amount in the same direction itmoves when brakes are applied to force the shoes upward, and replacecam in its operating position.(e) Tighten brake lever locking nut, and reassemble disk-and-rimwheel hub.d. Wheel bearings should be adjusted to prevent drag.e. Brake cam and rollers are lubricated through fittings. Lubrica-tion must be correct to avoid the brake lining becoming saturated.

Over lubrication will cause heavy brake handle pressure and maymake necessary replacement of brake linings. Linings may be cleanedwith dry-cleaning solvent.37. Lubrication instructions.-a. Excessive wear can be pre-vented by keeping materiel clean and well lubricated. The life ofgun and carriage depends on proper lubrication. Particular at-tention should be given to sliding and bearing surfaces such as inclinedplanes on gun and cradle and roller paths, roller bearings, and breechmechanism.b. Lubricating oils and greases as shown in lubrication charts mustbe used as prescribed.c. The lubrication charts shown in figures 1 to 4, inclusive, are pro-vided for information and guidance.295667-41- 3 33


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75-MM GUN MATERIEL, M1 897, AND MODIFICATIONS

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75-MM GUN MATERIEL, M1897, AND MOI)IFICATIONS

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ORDNANCE DEPARTMENT

RECOIL MECHANISMF HOLDING CRADLE

ELEVATING ARC

PTOPARRIAGE

BRACKETW AXLE TB RA FS D t746F-RICHT AXLE BiRAC.KET

FIGUnE 19.-75-mm gun carriage, M2A2, with shield an d wheels removed, right side view.

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NA4

SH O U L D E RX GUARD -

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FIGURE 20-75-mm gu n carriage, M2A2, with shield and wheels remov ed, left side view.

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FIRING JACK / /HOUSING OLT IFIRING JACKIHOUSNG /C,RATCHET PLUNGER'RIGHT RATCHET HOU5INGWORM WHEELPINION C O V E R -SHOT BOLTFIRING JACK RACKFIRING JACK FOOT

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HANDWHEEL, TRAVERSING,

TRAILLEFT, ASSEMBLY -

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RA FSD 2016FIGUIE 28.-AM2A2 carriage, firing position.

TELESCOPE, PANORAMIC-

GUARD,SHOULDER,ASSEMBLY

RA FSD 2,017.FiGUrE 29.--M2A2 carriage, traveling position.

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- PIN,LOGK,FRONT\i -- HANDWHEEL ,ELEVATING

-- CASE,TELESCOPE,PANORAMIG',--: -TELESCOPE,PANORAMIC

FIGURE 30.--M2A2 carriage, left side.

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- LUNETTE (QrORIZED)

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FIGURE 32.-M2A2 carriage, rear view.

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FIGURE 33.--75-mm gun carriage, M2A3, front view.

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CHAPTER 3SIGHTING AND FIRE-CONTROL EQUIPMENTParagraphsSection I. Sighting equipment ---------------------------- 43-51II. Fire-control equipment .....- 52-58

SECTION ISIGHTING EQUIPMENT Paragraph

Lamp, aiming post (lantern, M2) ----- ----- ----- ----- ----- ----- ---- 43Mount, telescope, M15 and panoramic telescope, M5 or MSA2 -------------- 44Mounts, telescopes, M15A1 and M22 and panoramic telescopes, M5A4 andM12A1---------- ---------------------------------------------------. 45Post, aiming, Ml __---_-----_- -_.________-__________________-________6Quadrant, gunner's ...... - ----_-..._-_----_ -_------------------- 47Quadrant, range ____------------------------------ __________________ 48Sight, bore ----........................................ _.__________ 49Sight, M101 (French) _______ __.._..________----______________________ 50Target, testing -------------------------.------------------------------- 5.1

43. Lamp, aiming post (lantern, M2).-This equipment com-plete consists of two aiming lanterns, M2 (with red lenses), one extragreen lens, two shields, and two adapters.a. The aiming lantern, M2 (fig. 39), is a small lantern of the typeformerly used extensively for automobile side lamps. The lanternhas a nonlosable burner burning kerosene and delivering about 7candlepower. A standard No. 00 (l%2 inch) flat wick is used.

b. Aiming lantern adapter fits the mounting device on the rear ofthe lantern and clamps on an aiming post.o. Shield snaps around the rim of the lens and serves as a hood tocut off stray light.

d. The lantern should be burned in a vertical position. Keep thewick trimmed and the lens clean. Do not turn the wick up so highthat the lantern smokes. Top of the lantern becomes hot in use andcare must be taken to have no combustible material in close proximityto it. When not in use keep the various parts in the chest.

44. Mount, telescope, 1VM15 and panoramic telescope, M5 orM5A2.-This telescope and mount (fig. 40) furnished with each75-mm gun and carriage, M2, M2Al, or M2A2, form the sighting cle-ment for aiming the gun. The mount is of the azimuth compensating

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ORDNANCE DEPARTMENTtype, automatically applying the necessary azimuth correction forcant. It is mounted on the left side of the carriage. Telescope andmount are being equipped with instrument light, MT.a. Description of nwunt.-The body of the mount, which supportsthe telescope socket, is positioned in part by a central pivot which ispermanently alined to the bore of the gun. The body is also posi-tioned longitudinally and in cross level by knobs operating wormdrives. Two levels are provided. The cross level when centeredindicates the normal line of sight of the telescope to lie in a vertical

Ficvun 39.-Aiming lantern, M2.plane parallel to the bore of the gun, while the longitudinal level whencentered indicates the telescope to be vertical and hence deflections(azimuths) indicated on the scale are then measured in a truly hori-zontal plane. For traveling, a locking device is provided whichholds the mount in the position shown in figure 41.b. Desciptionof telescope.-The panoramic telescope, M5 or M5A2,is a four-power telescope with a rotating head and azimuth mechanismby which the line of sight may be directed to any desired azimuth, andwith a movable prism permitting the line of sight to be elevated or

depressed through a limited angle as required to keep the aimingpoint within the field of view. The image viewed by the observer iserect. Both objective and eyepiece are the fixed focus type designedfor normal eyesight and for ranges ordinarily encountered. The82

TM 9-30544


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reticle contains a vertical and a horizontal cross line, the latter beingmarked at 5-mil intervals and numbered at the 50-mil point on eachside. The line of sight is elevated or depressed by means of the knobat the top, and coarse and fine index graduations are provided for the

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means of the associated knob which has a throw-out lever to permitdisengagement for rapid motion when required. Indications by theazimuth micrometer index opposite the black graduations of the asso-ciated scale which is graduated at 1-mil intervals supplement thoseon the azimuth scale. The micrometer scale also indicates deflections,black graduations for deflections to the left and red graduations fordeflections to the right. Thle micrometer scale is arranged to be offsetfor insertion of corrections by means of the deflection knob. A detenton this motion gives a distinct click for each 1-mil movement and the

OIL'

PLUNGERHANDLE

RA FSDLONGITUDINAL WORM 493ATHROWOUT LEVER

FIG.U1iE 41.-Telescope mount, M115, traveling position.

total correction is indicated by the fixed deflection index. The tele-scope, which fits in cylindrical locating surfaces of the support, has aprojecting lug to locate it correctly in azimuth. It is removable fortraveling.c. Operation.-(1) Preparction.-Toplace the mount and telescope

in operation (fig. 41) remove the cover, grasp the socket in one handand with the other push the plunger handle down, then to the leftand release. Swing the socket to an approximately vertical positionand with the free hand push the longitudinal worm throw-out leverclockwise until it snaps in place. Release the socket. Remove tele-scope from case. Turn tie retaining knob to its extreme counterclock-wise position and place telescope gently in the socket. Exert slight

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TM 9-30575-MM GUN MATIERIEL, M1897, AND MODIFICATIONS 44

pressure downward to insure that both top and bottom alining sur-faces are firmly engaged. Uncover both levels.(2) Procedure.--Operating rocedure depends upon whether director indirect laying is to be employed, instructions for which are givenseparately. The procedure given is for uncorrected fire. Corrections((5) below) are equally applicable to either kind of laying.(3) Direct laying.-(a) Set telescope in elevation to normal andleave in this position as long as direct laying is used. Set micrometerscale to indicate zero deflection, opposite the fixed outer index.(b) Set the lateral deflection to the desired value, using the com-bined indications on the azimuth scale (100-mil steps) and on the azi-muth micrometer scale (1-mil steps). Deflections to left (trajectorydisplaced to left of line of sight) are indicated by the letter "L" andblack scale designations. Deflections to right (trajectory displaced toright of line of sight) are indicated by the letter "R" and red scaledesignations. The azimuth scale has black numbering for left deflec-tions only. For right deflections, subtract the value of the deflectionfrom 3,200, or count the graduations backward from the zero of theazimuth scale. The azimuth wornt may be disengaged for making]arge changes in deflection rapidly by depressing the throw-out lever.

(c) Operate the cross leveling knob of telescope mount so thatbubble of the cross level is continuously centered with respect to thegraduations on the vial as long as firing is continued. Operate thelongitudinal knob of telescope mount so that the horizontal crossline of the telescope reticle remains continuously on the target.Disregard the position of the longitudinal level.(d) Operate traversing handwheel on the gun carriage so thatthe vertical cross line of telescope reticle remains continuously on thetarget. The piece is then properly laid in direction for direct laying.(4) Indirect laying.-(a) Set azimuth micrometer scale to indi-cate zero deflection opposite the fixed outer index.(b) Set firing angle to desired value, using the combined indica-tions on the azimuth scale (100-mil steps) and on the azimuth mi-

crometer scale (1-mil steps). Disregard red markings on the scale.Firing angle is the horizontal clockwise angle, apex of which is atthe piece, measured from target to aiming point. For values up to3,200 mils it is numerically equal to the value indicated on the azi-muth scale of the telescope, the rotating head being directed to right ofline of fire. For values of firing angle greater than 3,200 mils, sub-tract 3,200 from the value of the angle and make the setting withthe rotating head directed to left of line of fire. The azimuth worm

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may be disengaged for making large changes in azimuth by depress-ing the throw-out lever.

(c) Operate the longitudinal and cross leveling knobs of telescopemount so that the bubbles of both levels are continuously centeredwith respect to the graduations on vials as long as firing is continued.

(d) Operate the traversing handwheel on the gun carriage so thatthe vertical cross line of the telescope reticle remains continuously onaiming point. The telescope may be elevated or depressed by theknob at the top as required to bring aiming point within field of view.It is not necessary to bring aiming point exactly on horizontal crossline. The piece is then properly pointed in direction for indirectlaying.(5) Corrections.-Corrections o firing angles or deflections maybe introduced by using either of the two methods described below.

(a) First alternative method.-The micrometer scale is not offsetbut remains as originally set to indicate zero opposite the outerindex. Corrections are introduced in the same manner as in mak-ing original azimuth or deflection settings by turning the azimuthmicrometer index in the proper direction through the required numberof 1-mil di

TM 9-305 ( 75-Mm Materiel, M1897 and Modifications

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Transcript of TM 9-305 ( 75-Mm Materiel, M1897 and Modifications