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T 9-759

W R EP RTMENT

TECHNICAL MANUAL

MEDIUM TANK M 4A3AUGUST 4 1942

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T 9-759

TECHN ICAL MANUAL WAR DEPA RTMEN TNo . 9-759 W ash ing ton Augus t 4 9 4

MEDIUM TANK M4A3Prepared under the direction of

the Chief of Ordnancewith the cooperation of the Ford Motor Company)

CONTENTSParagraphs Pages

SECT ION I: Introduction ................................... ..... 1 3 2II: Description andtabulated data........ .. 4 5 3 7

III: Operating instructions and controls.. 6 11 8 22IV: Lubrication ........................................12 16 2 3 2 7V: Inspections ........................................1722 28 33

VI: Power unit and accessories...............23 37 3454VII: References ..........................................38 40 55

IN D EX ............................................................................ 56 62

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TM 9 7591 3MEDIUM TANK M4A3

SectionI

INTRODUCTIONParagraph

Purpose andscope................................................. .........................Content and arrangement of the manual.................................... 2References ................................................... .. ................................. 31 PURPOSE AND SCOPE

TM 9-759 dated August 4 , 1942 , is intended to serve temporarily(pending the publication of arevision now in preparation whichwillbe wider in scope) to give information and guidance to the personnelof the using arms charged with the operation and maintenance ofthis materiel.2 CONTENT AND ARRANGEMENT OF THE MANUAL

Sections I through V contain information chiefly for the guidanceof operating personnel. Section V I contains information intendedchiefly for the guidance of personnel doing maintenance work.3 REFEREN ES

Section VII lists all Standard Nomenclature Lists, TechnicalManuals, and other publications for thematerial described herein.

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TM 9 7594 5Section

DESCRIPTION AND TABULATED DATAParagraph

Description ............................ ....................... ................................. 4Tabulated data................................................................................ 54 . DESCRIPTION figs. and 2).

a. The medium tank M 4 A3 is an armored, full track-layingvehicle, powered by a 500 hp Ford tank engine which is an eightcylinder, liquid cooled, V type engine designed specifically fortanks. The engine is located in the rearof the hull. The operatorsteers thevehicle by means of two levers located in the front endofthe hull. The vehicle has five forward speeds and one reverse. Thetank is wired for radio installation, and for an interphone systemwithin the tank.

b. The turret armor front is 3 inches thick, sides are 2 inchesthick, and rear is 2 inches thick. The top of the turret is inchthick. The armor on the sides of the hull is ' /> inches thick and thefront slope is 2 inches thick.c. The turret can be rotated through 360 degrees by a hydraulicsystem or by hand. The turret platform rotates with the turret.

d. An auxiliary electrical generating system, consisting of agenerating set powered by a one-cylinder two-cycle gasoline engine,charges the batterieswhen theengine generator is not operating.5 T BUL TED DATA

a. GeneralWeight without armament, fuel or crew 59560 IbGround clearance ........................... ......._....................................17%-in.Tread center to center of tracks)............................................__._..83-in.Width over-all ................................................................................103-in.Lengthover-all ..........................................................................232i/2 -in.Height over-all ..........................................................................111%-in.b Engine

Ford tank engineRated horsepow er.......................................__..__..._...........500 at 2600 rpmNumber of cylinders (60 V)..................................................................8Weight of engine, w/accessories..................................................1470 Ibc rmament

1 gun, 75-mm , M 3 combination turret mount)1 gun, machine, cal. .30, M 1 9 1 9 A 4 combination turret mount) gun, machine, cal. .3 0 , M 1919A4

flexible ball mount in front plate)

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T 9 759

MEDIUM TANK MA

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TM 9-759

DESCRIPTION AND TABULATED DATA

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TM 9-759

MEDIUM TANK M4A3 gun, machine, cal. .50 M 2,H.B .(f lexiblerace mount onturret hatch)

gun, submachine, cal. .45 Thompson, Model 1928A1(carriedon brackets within tank)mount, tripod, machine gun, M1928A1, cal. .30 M2d. Protected vision. Protected vision is provided for the driverand crew bythe use of steel shutters (open andshut type) at visionslots, and by indirect visiondevices called periscopes. There are fiveperiscopes on theM 4 A 3tank. Theperiscopes for the assistant driverand the gunner are telescope equipped. The remaining three periscopes are of the plain vision type.e. Seats. Adjustable, padded, chair-type seats, equipped withsafety belts, are provided for driver, assistant driver, and gunner.Round, padded seats, equipped with safety belts and of the snapdown type, are pro vided forthe loader and tank commander.f. ProtectivePadding. Partsof the interiorare padded withsponge rubber, to protect the tank crew frominjury.g. Communication

[SCR 245 sending and receiving(1) Radio...........,) Voice 15-25 miles[Code 30-45 miles(2) Telephone ........................................... ............................. Intra-tank

h Armor thicknessHull, front slope................2-in. Bottom, front....................1-in.Rear ........I'/a-in. Bottom, rear ....:...............i/.j-in.Sides ..............................11/2-hi. Turret, front......................3-in.Top .. . -in. Sid es and rear....................2-in.Top ....................................1-in .Rear ....................................2-in.i. Turret. Cast armor plate..................................... . . .360 traversej. Fuel andoilFullcapacity .............................................................................. . . . .174 galNumber of miles without refueling............ C ross country 110milesiHighway 155 milesOctane rating offuel..................................................... . . . . . . .80 or higherEngine oil capacity.......................................................................32 qtsLubricants......................................................See Lubrication Chartk PerformanceM aximumsustained speed on hard ro ad....................................26 mphExpected cross-country speeds for various terrains... ....4 to26 mphMaximum allowable engine speed............................................2800 rpmMinimumengine idling speed....................................................500 rpm

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TM 9 7595

DESCRIPTION AND TABULATED DATAMaximum grade ascending ability 27Maximumgrade descending ability 27Maximum width ofditch tank will cross...............................72-in.Maximum vertical obstacle such as a wall, that the tankwill climb over........-... ............................18-in.Maximum fording depth (at slowest forward speed)..................36-in.

1 Crew 5 menm. Tracks .-...........-...................................rubber block or steelTrack shoewidth...................................... .............................16-in.

Track pitch ................................................................... 6-in.

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TM 9-7596MEDIUM TANK M4A3

Section III

OPERATING INSTRUCTIONS AND CONTROLSParagraph

General information on controls................................................ 6Prestarting inspection .................................................................. 7Starting instructions .................................................................... 8Engine test .................................................................................... 9Operating the vehicle................................................................... 10Stopping the engine...................................................................... 116 GENER L INFORM TION ON CONTROLS f i g s . 3 nd 4 .

a. Spark control. The spark control is entirely automatic andrequires no attention by the operator of the vehicle.

b. Throttle controls. A foot throttle pedal is located on the floorin front of the driver's seat, convenient to the driver's right foot.In conjunction with the foot pedal, a hand-operated throttle is provided, which is bracket mounted to the differential case above thefoot throttle.

c. Steering levers Two steering levers are mounted on the floorof the vehicle, in front of the driver's seat. To steer the vehicle, pullthe steering lever on the side toward which it is desired to turn.Pulling back either one of the levers slows down the track on thatside, while the the speed of the other track is increased. Thus thevehicle turns with power on both tracks at all times (fig. 3).

d. Brakes1) Service brakes. Pulling back simultaneously on both steeringlevers slows down or stops the vehicle, depending on the effort

applied.(2) Parking brake. The parking brake lever is located on theright side of the driver, at rear of the transmission. It is a transmission typ brake, and should never be used for any purpose otherthan parking. Always be sure parking brake is released beforemoving the tank.

e. Clutch. The clutch pedal is located on the floor in front ofdriver's seat, convenient to the driver's left foot. To permit shiftingof gears, the clutch is disengaged by depressing the clutch pedal.f Utility outlet Two utility outlets are provided at the top ofthe instrument panel that permit plugging in trouble light, windshield wiper, etc.g. Light switches. The knob on the instrument panel markedLIGHTS controls the service lights and the blackout driving

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OPERATING INSTRUCTIONS AND ONTROLSTM 9-7596

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TM 9-7596

OPERATING INSTRUCTIONS AND CONTROLS

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lights. A spring-operated safety button prevents the knob frombeing accidentally pulled out beyond the blackout position. Torelease, push button in with thumb, at the same time continuingoutward pull on knob with first and second fingers. The switch hasthree positions (besides OFF ), controlling lights as follows:Light Switch Position Lights Operating

Blackout1st position Blackout headlightsBlackout taillightsBlackout stop light

Service2nd position Service headlightsService taillightService stop light

Stop light3rd position Service stop light

LocationTop of right andleft headlightsLower section right

and left taillightsUpper section righthand taillightRight and leftheadlightsUpper section left

hand taillightUpper section left

hand taillightUpper section lefthand taillight

h. Blackout driving light switch. The blackout driving light maybe used to supply illumination for driving when the service drivinglights might reveal the position of the tank. First, remove bothservice headlights from their sockets at the front of the tank. Theninsert the blackout driving light in the left front lamp socket. Withthe master light switch pulled out to first position, pull out on blackout driving light switch button to turn on driving light. The blackout headlight, taillights, and stop light will also be on with switchesin this position. CAUTION: Under battle conditions the blackoutdriving light should be used intermittently and only when absolutelynecessary for safe vision.

i. Starter switch. Directly beneath the blackout drive switch astarter button is provided. When pushed in this button completescircuit through the starter switch solenoid closing the starting motorcircuit, causing the starter to crank the engine.

j. Primer. A priming pump is provided and located to the left ofthe starter button. To operate the primer, the button is pulled outand pushed back in. This causes a quantity of gasoline to be forceddirectly into the intake manifold for cold weather starting. Thepriming pump is used in place of the conventional choke. Ordinarilyit will not be necessary to use the primer except during cold weather.1 2

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6OPERATING INSTRUCTIONS AND CONTROLS

Excessive priming of the engine will cause flooding and failuretostart, and the excess gasoline w ill washthe oil from the cylinderwalls with the result that the cylinder will not be properly lubricateduntil the engine oil starts circulating.

k. Ignition switch. The Ford tank engine uses two 4-cylinderBosch magnetos which are controlled by a 4-position switch in thecenter of the instrument panel at the top. When the switch lever isto the left, both magnetos are on. When the switch lever is at theposition marked L the left hand magneto only is on, and the enginewould be running on the left hand four cylinders. Leftor right areused with reference to the engine as viewed from the rear of thetank. When the ignition switch lever is at the position marked Rthe right hand magneto is on and the engine will run on the fourcylinders on the right hand bank only.

1 Fuel cut-out. To the left of the ignition switch a spring loadedtoggle switch is provided which operates the carburetor degasserelectrically. When stopping the engine always pull this toggleswitch to the right and hold in this position until the engine stopsbefore turning off the ignition. This shuts off the fuel from the idlefuel supply wells in the carburetor. This will prevent loading up ofthecarburetor in case the engine is tobe restarted while still hot.

m. Circuit breakers. Six circuit breaker buttons areprovided inthe upper left hand corner of the instrument panel, which controlthesix circuit breakers which take the place of the conventionalfuses. In each instance when these circuits are overloaded, thecircuit breaker will open. The circuit involved is then closed merelybypressing the correct button. The circuits controlled by these sixbuttons are as follows (fig. 4):(h) Right hand utility outlet circuit

(j) Left hand utility outlet circuit(k) Blackout drive switch circuit(1) Siren circuit(m) Fuel cut-off andhull lamps circuits(n) Circuit for panellights, fuel gage, water temperature, lowpressure light, oil level gage, voltmeter, and transmission oil tem

perature gage.n. Clock. Directly beneath the six circuit breaker buttons an8-day clock is provided. A reset andrewinding knob is located at thebottom ofthe dial.o. Compartmentlight rheostat. To the left of the clock a 5-posi-tion rheostat is provided which controls the brilliance of the panellights.

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TM 9 7596

MEDIUM TANK M4A3p. Voltmeter. To the rightof the clock a voltmeterhavinga

rangefrom 16 to 32 volts is provided. When the battery masterswitch is off, the voltmeter will read at the lower end of the scale.When the master switch is on, thevoltmeter should read batteryvoltage (approximately 24 volts). If reading is low with the enginenot running and no electrical energy is being used, the batteries arelow in charge and should be recharged. At normaloperating speedsduring normal ambient temperatures, the voltage should not exceed30volts. f the reading is greater than this, the generator regulatoris not properly limiting the voltage, andshould be replaced; otherwise the generator will burn out. This voltmeter likewise reads whiletheauxiliary generating unit is charging the battery, at which timethe voltage should not exceed 30 volts.

q. Ammeter. To the right of the voltmeter an ammeter is provided with a rangeof 100 ampere discharge to 100 ampere charge.fduring normal operation when little current is being used, theammeter consistently indicates discharge either the generator regulator is not functioning properly or the generator itself is at fault.In either case the batteryis not being charged and will quicklydischarge. These units should receive immediate attention to preventfailure during operation. Even withno electrical energy being usedthe ammeter shouldnever go above 50 amperes (plus or charge)100 amperes on tanks having two generators). If the ammeterindicates more than 50 ampere charge, 100 amperes on tanks having two generators) the current limiting unit in the generator regulator is at fault and the regulator should be replaced; otherwise thegenerator will burn out during operation.

r. Oil temperature gage. To the right of the ammeter an oiltemperature gage having a range of from 100 to 325 degrees indicates thetemperature of the oil in the transmission.

s. Tachometer. Thetachometer is located on the right hand sideof the instrument panel to the left of the transmission oil temperature gage. The throttle stop screw on thecarburetor should be soadjusted that the engine should idle at 500 rpm after warm-up.The maximum speed of the engine is governed by a flyball typegovernor located at the rear of the right hand cylinder head. Thisgovernor is set to limit the engine speed to 2650 rpmunder full loadwith wide open throttle 10-inch vacuum). If during operationunder full load it is possible to run the engine at speeds above2650rpm, or if the governor limits the speed at some point below 2650rpm, the ordnance maintenance personnel will be notified. If thegovernor is set too lo w it will be impossible to get maximum speedand power from the vehicle; on theother hand if the governor is settoohigh, damage to the engine and other working parts could result.

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TM 9 7596

OPERATING INSTRUCTIONS AND CONTROLSt. Oilpressure gage. An engine oil pressure gage is locateddirectly beneath the tachometer. At normal temperaturesthe oil

pressure should be between 60 and 80 pounds. If during operationthe oil pressure suddenly drops off, immediately stop the engine.This fault may be due to low oil level. Ifoil pressure dropsoffslo wly,it may be due to a change in the viscosity of the oil dueto overheating. Check engine temperature.

u. Low oil pressuresignals. To the right of the oil pressure gagea red jeweltype light isprovided that signals the driver when theoil pressuredrops below eight pounds.v. Oil levelgage. An oil level gage located between the speedometer and theoil pressure gage indicates whether sufficient oil iscarried in the oilpan sump. A s long asthe oil level gage is in thegreen sector, the oil level is satisfactory. When the readingdrops

to the red sector, oil should be added tobring the reading up to theright hand side of thegreen sector.w. Speedometer. The speedometer is locatedin the center of theinstrument panel at the bottom, and is equipped with a trip mileagereset atthebottom of the instrument panel.x. Engine temperature gage. The engine temperaturegage islocated to the left of the speedometer and is calibrated from100 to260 degrees. The cooling system on the M 4A3 tankis sealed and notOpento atmospheric pressure, with theresult that boiling point ofthe coolant and consequently overheating actually does not occuruntil a temperatureof approximately 230 degrees isreached. Innormal operation under maximum power on a level hard surfacethe engine temperature should not be greater than 90 degreesabove

atmospheric temperature.y. Fuel level gage and selector switch. In the lower left handcorner of theinstrument panel a selector switchand fuel levelgage,permit the checking of the fuel level in the two sponson fueltanks.

The selector switch has three positions L (left), Off, and R(right). With the selector switch in the Off position the fuel levelgage willread E (empty). With the selector switch in the leftposition the fuel level gage will indicate the level of the fuel in theleft hand sponsontank. With the selector switch inthe R positionthe fuel level gage will indicate the level of the fuel in the right handsponson tank.

z. Battery master switch (fig. 5). A battery master switch islocatedapproximately 30 inches to the rear of the driver's seat andunderneath the turret basket floor. To open or closethis switch, itis necessary to raise the knob approximately Vii-inch and turn.When this switchis open all electrical power isshut off at the battery

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TM 9 759OPERATING INSTRUCTIONS NDCONTROLS

Figure Gear Shiftl v rPositions

(with the exception ofthe power usedby theradiowhichis controlled bya separate radiomaster switch). If in doubt as to whethertheb ttery masterswitch ison, thefollowingcanserve as aguide.Whentheb tterymasterswitch is off, the engine temperaturegagewill read FullScale 260deg.)and the oil level gage will read tthebottomof the red sector. Whenthe bttery master switchis on,theengine temperaturegage will indicatethetemperatureof thecoolant in theengine, orif its temperatureis below 100 degreesitwill indicate 100 degrees, andthe oil level gagewillindicatetheoille vel and should be in the greensector.

aa. Gearshifting fig . 6)(1) Description. Shiftingofgears in thetransmissionforspeedchanges is accomplishedby the gearshift lever, locatedon theleft

sideof thetransmission,tothe right of the driver. Thepositions ofthe gearshift leverfor thevariousspeeds are shownin figure6. Thegearshift lever is equippedwith a latchwhich preventsaccidentalshifting intofirstspeedor reverse. The latchmustbe released bypressingdown the buttonon topof the lever beforeshiftingintofirstspeed or reverse.(2) Operation. When itis desired toshift tolowor reverse, the

following procedurewill makethe shiftpossiblewithoutthe clash-17

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TM 9-7596-9MEDIUM TANK M4A3

ing of gears which usually results. From neutral move the gearshift lever as though to shift into third gear. Maintain pressure inthis direction long enough to stop the propeller shaft and then, withthe clutch still held out, shift smartly into low or reverse. If whenshifting to any of the higher speeds there is araking of gears,goback toneutral and, still holding the clutch out, start the shift over.

Beforetheengine is startedfollow procedure outlinedunder pre-starting inspection inSection V.

Before attempting to start the engine,familiarize yourself withall of thevarious instruments and controls, as outlined in paragraph 6; make sure thatthefunction of each controlis thoroughlyunderstood and that the significance of thereadings on the variousinstruments isappreciated.

a. Open gasolineshut-off valves which arelocated in the leftside of the fightingcompartment (fig.7). If the fuel tanks are full,runfrom right tanks for 30 minutestoprovide expansion space forthe fuel before opening valves onleft fuel tank.

b. Close battery master switch.c. Put gear shift lever in neutral.d. Pull hand throttle out about '^.-inch.e. Incold weather prime the engine three to ninequick pulls onthe primer, dependingon outside temperature.f. Depress clutch pedal.g. Turn magneto switch to both position.h. Press starter button.i. Engine shouldstart readily.

a. As soon asthe engine starts check oil pressure. Stop engineif the oil pressure is not indicated in 30 seconds.b. Check the operation of instruments and switcheswhile theengineis idling. Idle engine until engine temperature gage reads

above 100 degrees.c. Whenengine is sufficiently warm set hand throttle to 800rpm.Runthe engine on each magneto and compare each tachometer reading withthe reading when both magnetos wereused. When eithermagnetoshows a dropto less than 400 rpm, the cause should beinvestigated.

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TM 9-7596 -9OPERATING INSTRUCTIONS AND CONTROLS

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TM 9 759MEDIUM TANK M4A3

d. Push hand throttle in, (Carburetor stop screws should be setto idle the engine at 500 rpm after warming up.) Never idle theengine at le ss than 500 rpm.e. Never lug engine below 1000 rpm at wide open throttle. Shiftto a lower gear.

f. Check oil pressureand temperature frequently.

Before attempting to drive the vehicle the prospective drivershould be thoroughly familiar with all the instruments and thesignificance of their readings. One must also know the functionand operationof the controlsin the compartment. Review of paragraph 5 will be helpful. The limitations of vehicle and enginearecovered under paragraph 4 :

a Operating instructions. With the driverin the driver's seat,the engine at idling speed, and all instruments showing normal readings, the driver may now operate thevehicle.(1) Release the parking brake. This is important.(2) Disengage the clutch by pressing clutch pedal down to thefloor and holding it down.(3) Move the gear shift leverinto second gear, for normal operation. First gear will be used only when shifting vehicle in buildingsor over obstacles.(4) Gradually release theclutch pedal, at the same time depressing the foot throttle. Except when under fire, do not move thevehicle in orout of close quarters without the aid of personnel outside of the vehicle serving as a guide.(5) When the vehicle has started and is moving with enginespeed of 1200 rpm, release the foot throttle, depress the clutchagain, and move the gear shift lever into the third gear position.Release the clutch and again depress the throttle to pick up theload of the vehicle.(6) Repeat the above procedure until the highest gear is reachedwhich will enable the vehicle to proceed at the desiredspeed withoutcausingthe engineto labor. D o not ride the clutch. The driver's

left foot must be completely removed from the clutch pedal whiledriving, to avoid unnecessary wearand burning out the clutch.(7) To place the vehicle in reverse gear a complete stop must bemade, the throttle closed until the tachometer reads500 rpm (lowestidling speed). Depress theclutch pedal and move the gear shiftlever to the reverse position (f ig. 6). Backing the vehicle shouldnever be attempted unless an observeris stationed in front to guidethe driver.

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TM 9 7591

OPERATING INSTRUCTIONS AND CONTROLS(8) To steer the vehicle pull back the right hand steeringleverto make a right turn or the left hand lever for a left turn. This

actionbrakes the track on the inside of the turn andspeeds up theoutside track. The driver should anticipate each turn and be readyto apply morepower as it is needed to compensate for the brakingeffort. The hands should be, free of the steering lever when notactuallysteering the tank.

(9) To stop the vehicle, release the throttle and pull back onboth steering levers at the same time. Depress the clutch pedalwhen the vehicle has slowed down to approximately two to five milesper hour, depending upon which gear is being employed before stopping. Set the hand throttle for a tachometer reading of 500 rpmfor the duration of the halt.

(10) The tachometer, the oil temperature gage, and the oilpressure gage give the most satisfactory indications of the engine'sperformance. Should the indicationsof any of these instrumentsappear to be irregular, the engine should be stopped, and the causeinvestigated.

(1) A towing shackle is mounted on each corner ofthe hull of the vehicle about 20 inches from the ground. Two ofthese shackles are mounted in front and two in the rear. Theseshackles provide a quick method of attaching either the towingbar or cables.

(2) If there are tracks on the vehicle to be towed,always disconnect the propeller shaft at the transmission companionflange and leave the vehicle in fifth gear. This procedure insuresadequate circulation of the transmission oil while the vehicle is inmotion. If the tracks are removed before towing the vehicle, thisprecaution is not necessary. In towing there areseveral precautionsthat the driver must take to avoid trouble or unnecessary delay.Changes of direction are always to be made by a series of slightturns so that the vehicle being towed is as nearly as possible directlybehind the one doing the towing or tracking. This will preventthe cable from contacting the track, which might ruin both the cableand thetrack blocks. Soft muddy ground is to be avoided, since thetracks may slip on such a surface. If it is necessary to cross a muddyarea, the driver should be careful to straighten out both vehiclesbefore entering it, as it is more difficult to pull a tank at an anglethan when following in tow. Grousers may be installed as required.The maximum speed when towing should be not more than12 milesper hour and then only with an operator for steering and brakingthe towed vehicle. NOTE: Except in cases where a short hitch

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is absolutelynecessarya towing cable will not be coupled to anothervehicle by other than the thimbled eyes providedat both ends.Doubling the cable causes sharp bendsin the wire rope which willcause rapid failure of the strands and will leave the cable extremelydangerous to handle. When a short hitch is desired, thetwo eyesof the cable are attached tothetowing vehicle. The cable withleads is then passed through both shackles of the towedvehicle. This provides an arrangement having aminimum of bending action and movement at the shackles, and furnishes clearancebetween cable and tracks.

(3) If no operator is available to steer the disabledvehicle one cable will facilitate tracking ofthetowed vehicle. Caremust be taken on turning, not to get the cable tangled up with thetrack of either vehicle.

After completing arun, the engine must be allowed to operate at500 rpm for two minutes to assure a gradual and uniform coolingof thevalves and other various engineparts.

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TM 9 759Section IV

LUBRICATIONParagraph

General............................................................................................ 12Lubrication guide .......................................................................... 13Points to be lubricated by ordnance maintenance personnel.... 14Reports and records................................................................... 15Lubrication guide notes..-.....................-......... .......................... 16

The following lubricationinstructions for medium tank M 4 A3 arepublished for the informationand guidance of all concerned, andsupersede all previous instructions. Materiel must be lubricatedin accordance with the latest instructions contained in TechnicalManuals and/or Ordnance Field Service Bulletins.

(figs. 8 and 9).Lubrication instructions for all points to be servicedare shownin War Department Lubrication Guide No. 104, which specifies the

types oflubricants required and the intervals at which they areto be applied. The following lubrication instructions contain thesame information as the guide. Guides from which data are reproduced are 10x15 in. laminated charts whichare part of the accessoryequipment of each piece of materiel.

MAINTENANCE

Remove and repack generator bearings withGREASE, ball androller bearing, once each year.

If lubrication instructions are closely followed, properlubricants used, and satisfactory results are not obtained, a reportwill be made to the ordnance officer responsible for the maintenanceof the materiel.A complete record of lubrication servicing will be

kept for the materiel.

Additional lubrication and service instructionson individual unitsand parts:1. FITTINGS Clean beforeapplying lubricant. Lubricate bogie

wheels, idler and track support rollers, tachometer and speedometer23

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TM 9 759 6

MEDIUM TANK M4A3L ubricant nterv al nterval e L u br icant

Differential andfinal drivedrain plugs

NOTE: ee eve rse Sidefor other type construction)

Transmission drain ptug R e a c h ed f r o m u n d e r h u l l )

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S E R V I C E D R O M E N G I N EC O M P R T M E N T

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S E R V I C E D R O M F I G H T I N GC O M P R T M E N T

NOTE: e e Re ve r s eS i d e fo r o t h e r t y p ec o n s t r u c t i o n

S E R V I C E D R O M E N G I N EC O M P R T M E N T

KEY

TABLE OF CAPACITIES WITH RECOMMENDATIONS AT TEMPERATURES SHOWN

RA PD 7 4Figure 8 ubrication Chart on Power Drive Units

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TM 9 75916LUBRICATION

TANK. MEDIUM M4A3 G

SUSPEN SIO N SYSTEMInterval Lubricant

CAUTION-Lubricate

inal drain p u

ifferential drain plug

ransmission drain plug

O E

TU RR ETSUPPO R T B EA RING

T R A N SMISSIO N DIF FERENTIA L A N D

F I N A L DRIVES

G

O H

KE Y -LUBRICANTS INTERVALS

R A P D 7 43

Figure Lubrication hart on Suspension25

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adapters until grease overflows relief valve. Lubricate other fittingsuntil new grease is forced from the bearing, unless otherwise specified. CAUTION: Lubricate suspension points after washing tank.

2. INTERVALS The intervals indicated at points on Lubrication Guide are for normal service. For extreme conditions of speed,heat, water, mud, snow, rough roads, dust, etc., reduce interval onguide by 1 3 or /a. or more if conditions warrant.

3. AIR CLEANERS Proper maintenance of air cleaners isessential to prolonged engine life. Drain, clean and refill with OIL,engine, crankcase grade, daily, when operating on dirt roads or crosscountry; every 250 miles when operating on paved roads or duringwet weather. Depending on operating conditions, remove air cleaners and wash all parts every 100 to 500 miles. Inspect air outletrubber hose connections for leaks and make sure pipes are in aline-ment. Replace connections if there is evidence of wear or deterioration. CAUTION: Keep all air pipe connections tight.

4. CRANKCASE Check oil level daily, add oil if necessary.Drain every 500 miles or 50 hours when operating on dirt roads orcross country; every 1000 miles when operating on paved roads orduring wet weather. Drain only when engine is hot. Refill to FULLmark on bayonet gage, located on rear of engine on left side. Runengine a few minutes and recheck level. CAUTION: Be sure pressure gage indicates oil is circulating.

5. GEAR CASES On some assemblies, the transmission, differential and final drives are combined in one unit. These are filledthrough transmission filler only and drained through transmissionand final drive drain plug holes. Other assemblies use 3-piece units,filled through transmission filler and each final drive filler plug holeand drained through transmission, differential and final drive drainplug holes. Check level daily, add oil if necessary. Check with tankon level ground. Make visual inspection for leakage weekly. Reportleakage to ordnance maintenance personnel. Drain, flush and refillat end of first 250 miles; thereafter as indicated at points on Lubrication Guide. When draining, drain immediately after operation.To flush cases, fill to proper level with OIL, engine, SAE 10. Operatetank slowly in low gear for several minutes and redrain. Fill gearcases with OIL, engine, grade specified in table of capacities andrecommendations. CAUTION: Fill single piece unit to mark onbayonet gage with fill cap resting on top of fill pipe. Fill 3-pieceunit to 1 inch below final drive fill plug holes and to mark on transmission bayonet gage. Clean transmission filler strainer every 3000miles. CAUTION: Do not remove strainer when filling.

6 . AUXILIARY GENERATOR Two-cycled air cooled engine,mounted on turret floor, rear, is lubricated by OIL, engine, with fuel.26

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TM 975916LUBRICATION

Mix thoroughly % pint OIL, engine, SAE 30, with each gallon ofgasoline before pouring into tank. CAUTION: D o not pour gasolineand oil separately into tank. Keep fuel strainer clean. Magneto Every200 hours, lubricate magneto cam follower by oilingfelt withoneor two drops OIL, engine, SAE30 .7. FUEL FILTER Open drain cock dailyto remove sediment

and water. Every 1000 miles, remove element and wash in fuel orSOLVENT, dry-cleaning.8. UNIVERSALJOINTS A N D SLIP JOINT Remove tunnelshield sections over universal joints and slipjoint at ends of tunnel

shield. Lubricateuniversal joints through fittings with GREASE,generalpurpose, seasonal grade, until grease overflows at reliefvalve. To lubricate slipjoint, remove plug and insert fitting. ApplyGREASE, general purpose, seasonal grade, until grease isforcedfrom end ofspline. CAUTION: After lubricating, remove fittingand replaceplug.

9. OIL FILTER The oil filter isof the self-turning type andis located in the engine crankcase. Remove filter fromcrankcaseevery1000 miles, drain sediment from housing and reinstall.10. HYDRAULIC OIL TANK Located on side of turret. Checklevel every 2 5 0 miles by means of glasslevel gage. A dd OIL, hydraulic, if necessary. Drain, flush and refill every six months.

Capacity 12 quarts.11. OIL C A N POINTS Lubricate machine gun mount ball

socket, door and shield hinges, peep hole protector slides, doorlatches, lever bushings, control rod pins and clevises with OIL,engine, SAE 30 ,every250 miles.12. POINTS REQUIRING NO LUBRICATION Water pump,clutch pilot bearing, clutch yoke bearing, clutch release bearing,fan hubs, bogie wheel suspension linkage, final drive sprocketbearings.

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TM 9 75918 20

INSPECTIONSg Check for loose air horn connections from the carburetors toair cleaners.h. Check fuel level, fill if necessary.i. Check radio antenna for breaks.j. Check transmission oil level withbayonet gageon right sideof transmission, fill if necessary. D o not overfill, otherwise overheating will result.k. Check for oil and fuel leaks on floor of fightingcompartment.1 Check for presence and condition of fire extinguishers, andtank tools.m. Check instrument panel and see that voltmeterreads 16 withbattery switch open and otherinstruments indicate normal shut-offreadings.n. Check thatsteering levers, clutch pedal and gear shift leveroperate freely and over the full range.o. Close battery switch and watch the ammeter and voltmeter.The voltmeter should read 24 or more volts. If ammeter showsexcessive discharge, open the battery switch immediately.p. Check to see that fuel valves are open.q. Check lights and siren.r. Check operation of turret and locking mechanism.s. Check traverse and elevation of vehicle s weapons.t. Check to see that ammunition, flags, field equipment and rations if carried, are properly loaded.

a. During operation the driver will be on the alert to detectabnormal functioning of the engine. H e should be trained to detectunusual engine sounds or noises. H e should glance frequentlyatthe instrument panel gages to see if the engine is functioningproperly. An unsteady oil gage needle indicates low oil pressure,provided that engine speed is fairly constant. The driver shouldnotice continuously the amount of free play or clearance of theclutch pedal which should be at least tw o inches. The steeringmechanism must be checked for: clearance before engagement, intensity of pull required for braking, etc.b. Only underexceptional circumstances will a tank be operatedafter indications of trouble have been observed. W hen in doubt,the engine will be stopped, and assistance obtained Inspection during operation applies to the entire vehicle and should be emphasizedthroughout the driving instruction period.

a. At each halt the operator will make a careful inspection ofthe tank to determine its general mechanical condition. Minor de -29

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fects detected during the march, together with defects discoveredat the halt, will be corrected before resuming the march. If thedefects cannot be corrected during the halt, proper disposition ofthe vehicle will be made so that unnecessary delay may be avoidedand a major failure prevented.

b. A suitable general routine is as follows:(1) Elevate the 75-mm gun.(2) B y means of the ignition switch, cut out in turn each bankof cylinders to make sure all cylinders are firing. Allow the engineto run a short time on both magnetos at idling speed (500 rpm).Listen for unusual noises.(3) Walk around the vehicle looking carefully for fuel or oil leaks.(4) Examine tracks for adjustment and for worn, loose, broken

or missing parts.(5) Inspect hull and fittings for missing, worn, or loose parts.(6) Feel steering brake housings and gear case for evidence ofoverheating. If abnormally hot, check level or lubricant and ifnecessary correct steering brake band adjustment.(7) Inspect the lights, if traveling at night with lights.(8) Check the amount of fuel in the tank.(9) Wipe all windshield and vision devices. Do not use an oilyor dirty cloth.

At the conclusion of each day's operation, the tank commandershould cause an inspection to be made, similar to that made at haltsbut more thorough and detailed. The inspection should be followedby preventative maintenance. If defects cannot be corrected, theyshould be reported promptly to the chief of section or other designated individual. The following points should be covered:

a. Elevate the 75-mm gun.b. Examine the tracks and bogies.c. Check track tension.d. Inspect idler track support rollers.e. Examine the drive sprockets for worn or broken teeth.f. Examine the track shoe units for unserviceable units.g. Check transmission oil level.h. Check, clean and refill air cleaners during extremely dustyoperations.i. Clean crankcase breather.j. Inspect lights, siren and windshield wipers. Check for lossor damage of accessories.k. Inspect the sighting and vision devices for breakage.1 Inspect guns and mounts for defective performance.

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TM 9 759INSPECTIONS

m. Inspect guns, sighting equipment, andaccessories and determine that covers are properly installed.n. Inspect ammunition and sighting compartments for cleanliness and orderly arrangement.o. Replenish ammunition, engine oil and luel. A lw ays to uch thenozzle of the gasoline hose to the hull of the tank before removinggas tank cap to eliminate possibility of a static charge of electricityin either the tank or the gasoline truck from causing an explosionand fire w hen cap is removed from gas tanks. Don't fill the fueltanks all the way; leave air space of approximately three gallonsin each tank for fuel expansion.p. For continuous operation in hot weather, battery water mustbe replenished about twice a week. Check and clean battery andcompartment by removal of battery weekly.q. Drain and clean all floors through spring loaded valves provided, being sure to remove any accumulationfrom the engine compartmentthisis important to eliminate fire hazard.r. Check the operation of the full flow oil filters. Reverse themanual turning nut on the rotating spindle at the hydraulic motor

housing cover and crank the engine. The manual turning nut willrotate if the filter is operative.s. Inspect all control linkage to locate loose or broken parts.t. Inspect electrical wiring for loose connections.u. Check to see that the fuel shut-off valves are closed.v. Check to see that the battery switch is open.

a. After 250 miles of operation. This check is made without removing the engine from vehicle. (Check for leaks, etc., will be madewithengine compartment open and engine running.) Make routinedany inspection and the following:(1) Elevate the 75-mm gun.(2) Inspection for oil leaks at oil pan.(3) Check gasoline and oil lines for breaks, loose connections,and chafing. Check level of fuel in carburetor float bowl. Make ex

ternal inspection of rigidand flexible lines having sharp bends orkinks.(4) Remove the bolt passing through the fuel filter and remove

and clean thebowl and filter element. If excessive water or dirt isobserved, drain and clean fuel tanks.(5) Service air cleaner, do not overfill with oil. Check all air

induction pipes and airhorn for leaks. Check carburetor flangegasket.31

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TM 9759MEDIUM TANK M4A3

6) Check and adjust all control linkage for wear, free operationand missing cotter pins. Seethat full travel of controls is obtained.This applies to all controls of the vehicle.7) Check all flexible conduits for breaks and worn sections. 8) Tighten all engine mounting bolts .9) Check bogie, gudgeon nuts, wedges, wedge nuts, cotter pinsand lock wire for tightnessor broken and missingparts. 10) Checkpropeller shaft fla nge nuts for tightness.11) Check engine for excessive roughness. 12) Check suspension for track tension bogiewheeltires, volutespringsand presence of foreign material. 13) Changeengine oil. 14) Check oil level in transmission. 15) Service battery. 16) Check solenoids foroperation. 17) Check all accessories forsecurity and operation. 18) Road test forproperoperation. 19) Inspect fuel pump and, if leaking notify ordnance personnel.

b. After1000 miles of operation. Daily and 250 m ile check willbe repeated and the fo llowing in addition: 1) Elevate 75-mm gun. 2) Removeengine and place on inspection standand clean withSOLVENT, cleaning. 3) Disassembleclutch inspect plates lubricate clutch hub, spindle and throw-out bearings. 4) Check clutch throw-out bearing for wear and flat spots onraces. 5) Check all exhaust pipes for cracks burned out spots and rust. 6) Check intakemanifold gaskets and secure nuts for tightness.7) Rem ove radiators, clean all dirt in airpassages drain andflush out inside, completely removing flushingmaterial. 8) Change all spark plugs. Check new plugs. NOTE: Do notinstall sparkplugs untilall othertop cylinder work has been comple ted.9) Check flywheel cap screws for tightness and presence of

locking wire. 10) Inspect magnetobreaker and resetpoints to 0.014 to 0.016inch using feeler gage. Check points for pitting. If points showash coloredburning, have condensers checked. 11) Inspectcarburetor for float bowl fuel level. 12) Inspect starter and generator andbrushes, commutatorandgeneral internal appearance. Ifbrushes need replacing or if otherrepairs are indicated replace starter or generator.

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TM 9 75922

INSPE TIONS

13) Check all nuts securing engine accessories,fan and shroud,support brackets, etc., for tightness.14) Check throttle rod at clevises for loose jam nuts and cracks

at w elds. 15) Check foot accelerator to make sure both carburetors arewide open whenfoot throttle comes against stop.16) Check air horn rubber connections for restricted passages.17) Clean magnetic plugs in transmission and check magnetic

ability. 18) Check transmission oil.

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TM 9 75923

MEDIUM TANK M4A3Section VI

POWER UNIT AND ACCESSORIES ParagraphGeneral description and data................................................... 23Engine trouble shooting............................................ ................. 24M agnetos ....................................................-... 25Spark plugs ............................................. ...... 26Fuel pump ...................................................................................... 27Carburetors .............................. ............................................. 28Aircleaners ................................................ 29Governor .............................................................................. .... 30Valve mechanism .......................................................................... 31M anifo lds ............................................................................ .......... 32Engine replacement ..........I................................... ....................... . 33Starting motor ...................................................................... ........ 34Generator........................... .. ........................................................ .. . 35Oil pump ........................................................................................ 36Oil filter .......................................................................................... 37

(figs. 10, 11, 12,and 13).a. A 60 degree V 8-cylinder, 4-cycle, valve in the head, liquidcooled Ford tank engine is used. The cylinder block and crankcaseare a single casting of aluminum withoil hardened steel dry typesleeves in cylinder bores. The water jackets extend the full length

of cylinders which tends to speed up the warming of the engine oilin cold weather and to cool the oil after normal operating temperatures are reached. Four overhead camshafts are used, one exhaustand one intake for each bank of cylinders. There are tw o exhaustand two intake valves in each cylinder.b. The engine is mounted at therear of the tank and supportedby four brackets, the tw o front brackets are mounted on the bulkhead in the tank body; the two rear brackets are mounted on the

floor of the tank; rubber mounting is used between the brackets andthe engine.c. Two four cylinder magnetos are used. These are located atthe rear of the engine, one mounted at each end of a cross shaftdriven by spiral gears. The waterpump is driven from the end ofthe crankshaft. The two pusher type fans are driven by doublebelts from accessory drives located on the wall of the tank. Thegenerator is driven by theopposite end of the fan accessoryshaft.

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POWER UNIT AND ACCESSORIESTM9-759

23

5

5

30

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RPD2

U

e

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TM 9-75923POWER UNIT AND ACCESSORIES

N

RA PD 27203

Figure 2 Rear View of Engine

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TM9759MEDIUMTANKM4A3

R PD 27202

Figure 3 front iewofEngine

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T 975923

POWER UNIT AND ESSORIES

The oil pump (gear type is driven direct from the end of thevertical cam drive shaft.d. Theflywheelendof engine will be referredto as the frontofthe engine as the unit is mounted in the tankwith theflywheelforward. The terms right and left are used with referenceto the engine as viewed from the rear looking toward front ofthe tank.e. The following datainclude the generalinformation and enginecharacteristics which are frequentlyrequiredfor referenceMake and type....... ..... ........ ...... .... .Ford V 8-cylinder tank engine

Model .. .................................................................................... ............GAAOver-all dimensions...................... ...................... ......... .... ...60.38-in. long33.25-in.wide41.56-in. highWeight .. .. ......1470 Ib sHorsepow er ...... .................. ..........................................500 at 2600 rpmNumber of cylinders..-..-.-.--. ...8Bore ................................................ ................ ............ .. ................. ...5.4-in.Stroke ........................................................................................ ..........6 -in.Piston displacement. .................... ......................... 1100cu in .Compression ratio.. ............................. .... 7.5 to 1Directionof rotation viewed fromrear of engine)

Crankshaft ........... ....................... ............ ....................... .......ClockwiseStarter ............................................................................AnticlockwiseM ^Righthand .............................. ........................ClockwiseMagnetos Lgft hand AnticlockwiseAccessory speedsTachometer ............................ .. ......................... 1 / 2 Crankshaft speedGenerator 1.73 to Crankshaft speedMagneto ..............................................................V Crankshaft speed

MagnetoM ake and model...-.-- Bosch MJF-4A308Breakerpoint gap....... ...... .......... ........... ....... 0.014-in .-0.016-in.Sparkplug gap.................................... ................0.011-in.-0 .014-in.Valve clearance(non-adjustable) ...0.023-in.-0.0 28-in.Carburetormakeandmodel 2used)... .Bendix Stromberg NA-45G

Numberingofcylinders from rearto frontRight bank .. ................................... .. ............... .. ....1-2-3-4Left bank ...... ............ ........... ............ ............ ........ . 1-2-3-4

Firingorder.... .... ................................. ,1-R 2-L 3-R1-L 4-R 3-L2-R 4-L39

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(1) Checkthe specific gravity of the batteries. If reading is 1.225or le ss, replace with a fully, chargedbattery and have the dischargedbattery recharged. If reading is approximately 1.280the battery isfully charged.(2 ) Examine battery terminals for corro sion, battery cable fora short circuit or broken sections. If such conditions exist clean theterminals and replacethe brokencables.(3 ) Examine for loose connection at starter motor.(4) Press the starter button to determine if thestarter solenoidis working. Disconnect the battery-starter motor cable at thestartermotor and whileanother person operates the starter button holdthe cable against the housingand observe whether asparkoccurs.If no spark is seen, replacethe solenoid. If the starter does notoperate after replacing solenoid, rep lace the starter.(1) See that ignition switch is turned on.2) Check the amount of fuel in fuel tanks and besure the fuelvalvesare open.

(3) Under priming or over priming. For under prime reprimeengine with tw oor three additional strokes. For over prime placethrottle in full open position and turn engine over with starter fiveor six revolutions with magneto switchin off position.(4 ) Check fuel level in carburetors by removing float chamberlevel plugs (see fig. 14). If fuel is not apparent at the carburetor

levels, disconnect the inlet lines to carburetors and. crank enginewith starting motor. If no fuel flows, rem ove fuel pump outlet linesand blow out with air hose. .(5) After it-has been determined that fuelis being supplied tocarburetors the ignition system shouldbe checked as follows: Remove circular distributor plate fromright hand magneto and holdneon spark plug tester against each of the four high tension terminals in turn while engine is being cranked with the starter. A

bright flash willshow that the magneto, spark plu g s and wirefromthat terminal is operating satisfactorily. If dimlight shows, checkwire and spark plug. Follow same procedure with left hand magneto.If the neon tester is not available thetest may be made as follows:R emove the spark plug leadfrom the spark plug to be tested andhold it approximately V i inch away from a suitable ground connection Turn the engine over with the starting motor and if agood spark is noticed the circuit isin good condition. Testthe other40

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TM 9 75924

POWER UNIT AND CCESSORIES

R PD

ngine iring r ersparkplugs in the same manner. If testing in the bright sunlightthespark should be shielded so that itcan be seen. If test showsthat eitherof themagnetos arenot operating replace.

6) If the engine still will not start notify ordnance personnel.Too rich a mixture is evidenced by uneven runningand black smoke from the exhaust. oolean is evidenced by uneven running overheating or back-firing through thecarburetor

Examinecarburetor intake manifold flanges for tightness Also examine carburetor gaskets.In case of defective ignition it must firstbe determined whether the fault is in the right or left bank. Thiscan bedetermined by running first on the right bank and then onthe left bank by means of the ignition switch. In general whenonlyone cylinder misfires the fault is in the spark plug. Themostcommon plug difficulties areas follows:

The distance between the electrodes ofthe spark plug should be 0.011-inch to 0.014-inch. Too widea gap

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increases theelectrical resistance and interferes withthe operationof the engine.(b ) This is usually caused by a cracked orporous insulator, or by fouling of theelectrodes or insulator. Anyof these conditions will causemisfiring by permitting the current tostray from its intended path.

Misfiring of one cylinder, either continuousor intermittent maybe due also toachafed or broken wire. Themetalterminals of the cables must notcome into contact withanymetal parts of the engine or the magneto, except those designatedas being correct according tothe instructionsgiven. If the wiresand plugs are in good conditionand yet the ignition is irregular, thetrouble is probably with the magneto. This canbe checked as outlined in paragraph 25, b. It sometimes happens that distributor plate and control arm cap parts of the magneto are damagedthroughaccident or carelessness. These parts should also be carefullyexamined for possible disarrangement or damage which might permit leakage of current.

(4) Check the valve clearances,and thesprings. Makesure the valves arenot sticking.(5 ) Use only the recommended grade of gasoline andsee that it flows freelyto the carburetor.(6) Excessive engine temperature may bedue to anyof the following causes:(a) Airflow restricted through radiator.(b) Engine operating on too lean a fuel mixture.(c) Engine operating ona retarded spark.(d) Engine oil of improper grade, ofinsufficient quantity.

Two magnetos are used,one firing the cylindersin the right block and the otherfiring the cylinders in the left block.The right or left block is determined by looking at the enginefrom the rear of the tank, looking toward the front. The numbering of the cylinders and the firingorder is shown in figure 14. Thewires leading fromthe magneto distributorto the spark plugs maybeidentified for both right and lefthand magnetoby colors markedon the wires as follows: No. red, No. 2 blue, No. 3 green, and No. 4yellow.

(1) Open top engine compartment doors.(2) Remove plate over spark plugs in each block and removespark plug caps, wires andspark plugs.42

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POWER UNIT AND ACCESSORIESTM 9-75925

RA PD 27238

Figure 5 Turning Engine by Hand

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TM 9 7595

ME IUMT NKM4A3

RA PD 27235

Figure 6 onnectionsforMagnetoTimingLight

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TM 975925

POWER UNIT AND ACCESSORIES

Figure 17 Atagnefo Rotor rr w RA PD 27234

(3) Remove timing plate on flywheel housing in front of leftblock. To do this it is necessary to remove fire extinguisher nozzlebetween sideofleft block and wall of tank; also remove small Home-lite mufflermounted on bulkhead.

(4) Remove cover over rear universal joint and use bar forturning engine as shown in figure 15. Use compression gage inNo. 1 spark plug hole and turn engine counterclockwise or from rightto left until compression gage shows N o. piston is coming up oncompression stroke. Then turn until No. 1 cylinder right handmarkis approaching pointer in opening in flywheel housing.

(5) Remove magneto breaker point cover platesand connect oneof the red wires of thetiming light to the primary connection ofthe right hand magneto, and the other red wire to the primary connection of the left hand magneto. Then groundthe black wire toeither magnetoframe as shown in figure 16.

(6) O ne man should be in position to observe flywheel timingmarks, and another to turn engine a small amount at a time. Placethe ignition switch on instrument board on R ; turn engine onlya very small amount at a time untilright indicator light goes onshowing the breaker points havejust opened.

(7) The flywheel mark Spark Retarded should be under thepointer (fig. 17).

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9 759

MEDIUM TANK M4A3

(1) Should the flywheel mark be past the pointer when the timinglight goes on, the timing is late, in which case it will be necessaryto advance the magneto in the housing slots (fig.17).

(2 ) Loosen the upper and lower holding nuts and move the magneto counterclockwise,slightly back up the flywheel to remove backlash and check again. (C lockwise or counterclockwise is looking atmagnetos fromcoupling ends.)(3) Tighten holding nuts aftercorrect timing is obtained. NOTE:To time the left magneto, turnthe engine approximately two revolutions before using the compression gage on No. cylinder in theleft cylinder block. Turn ignition switch to L and proceed thesame as for right blo ck .

(a)Removethe four screws securing the breaker point inspectionplate and remove the plate.(b) Remove the four screws securing the magneto distributor

circular inspection plate; and remove the plate.(c) Remove the screw holding the ground wire.(d) Unscrew the knurled nut securing the groundwire conduitto the magneto housing, and remove the ground wire and conduit.(e) Remove the four screws securing the four ignition (hightension) cablesto the distributor plate and lift the ignition cablesout of therecesses.(f) Unscrewthe knurled nut securing the ignition cable conduitto the magneto and remove the conduit andcables.(g) Remove one upper and one lower nut securing the magnetoto the timing gear case and rem ove the magneto.(h) CAUTION: Note the position ofthe arrow in the center ofthe distributor plate before removing the magneto. The magnetomust be replaced with the arrow pointing to the same terminal aswhen removed.(2) Installation. Reversethe sequence ofremoval operations toinstall, and time the magneto in accordance with the procedure inparagraph 25 c.

a. Description. The spark plugs used are the Aircraft type,Champion C88-S, and are radio shielded. The spark gap is 0.011-inch to 0.014-inch. 6

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TM 9 7592628

POWER UNIT AND CCESSORIES

1 ) Remove plates over spark plug compartment, shield capsfrom spark plugs and spark plug wires. 2) Remove spark plugs.

When installing spark plugs do not use a wrenchwith handle more than 10 inches long. It is possible to distort certain sections of the plu gif too much force is used in tightening.

The fuel pump is of the automotive diaphragmtype AC) and is mounted on left cylinder bank and is driven byleft intake camshaft. The pump maintains a pressure of five poundsto thecarburetor.At the250 mile inspection check for leakage atconnections and fittings.

In the event the fuel pump fails to supply a sufficient quantity of fuel, the pump should be replaced witha serviceable unit. The follow ing procedure should be followed: 1) Close fuel shut-off valves. 2) Disconnect fuel lines attached to pump. Disconnect thepump to carburetor fuel lines at carburetor before attempting toremove from pump.) 3) Remove the two nuts which hold the pump to cylinder headand remove the pump.

Proceed in reverse order givenin paragraph 27 c.28.

Two Strombergmodel NA-Y5G Carburetors areused, one mounted at each end of the intake manifold. The carburetor is a double barreled down-draft unit. It has two floats connected by one lever and operating oneneedle valve. A separate mainmetering and idling system is provided for each barrel. Eachbarrel is equipped with a vacuum operated degasser and an electrical control for positive shut-off of the fuel when stopping theengine. This is controlled by a toggle switch on the instrumentpanel, and is used in case the engine continuesto turn over after theignition switch is cut off due to preignition or faulty wiring.

The idle fuel adjusting screws are shown infigure 18. There is one for each carburetor barrel. 1 ) Make idle fuel adjustments with engine stopped. 2) Seat each idle fuel adjusting screw lightly, and then turnout each screw 14 turn. There are two adjusting screws on eachcarburetor, one for each throttlebarrel.47

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MEDIUMTANKM4A3

R PD 733

Figure 8 Carburetor48

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TM 9 759POWER UNIT AND ACCESSORIES

3) Adjust idle speed adjusting screw so thatit is 14 turn openfromclosed position. 4) Start the engine and run until it reaches normal operatingtemperature. After engine is warmed up set idle speed adjustingscrew so that theengine idles at500 rpm.

To remove carburetors proceed as fo llows: 1) Remove the six nuts at the top of each carburetor whichhold the air cleaner manifo ld . 2) Disconnect the two air cleaner manifold hose pipes, by loose ning theclamps and remove air cleaner manifold. 3) Disconnect gas feed line at each carburetor. NOTE: A smallcorkshould be v il ble to cork the intake to prevent gasoline fromrunning outwhen feed line is disconnected. 4) Disconnect degasser electrical connections at each side ofcarburetor. 5) Remove the four carburetor base nuts which hold thecarburetor to the manifold. 6) Disconnect throttle rod at each carburetor and remove thecarburetors.

The carburetors may be replaced by reversingthe procedure outlined above.29 AIR CLEANERS.

Two air cle ners of the oil bath type arelocatedone at therightand one at the left of the fighting compartmentmountedon the forward sid e of the bulkhead.Daily or after every eighthours of operation inmild dust conditions service the air cleaners as follows: 1) Turn turret until the door in the turretexposes the air cleaner. Removethe three wing nuts from the bottomplate ofthecleaner and remove the baffle and cup assembly.Remove thebaffle fromthe cup and clean both baffle and cup thoroughly. Refill the cup toproper level with oil specified see lubrication chart, Section IV. Care should be taken not to fi ll the cup over

the oil level mark. Place thebottomplate on cleaner and fasten withthe threewing nuts. 2) After 25 hours of normal engineoperation, clean the filter element by first removing the baffle andcup assembly and then removing the filter element by pulling theclip down. Wash filter elements withcleaning fluid or gasoline. Dryand blow out with compressed air in reverse direction to normalair travel.

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(1) Turn turret until door in turret exposes air cleaner.(2) Disconnect rubber outlet connection to carburetor air intakemanifold(3) Remove the cup from the cleaner.(4) Remove four cap screws connecting cleaner to bulkhead.(5) Lift out cleaner.

Reverse the sequence of removal operation.

The governor is used to regulate and limit the speed of the engine,thus preventing dangerous over-speeding. The unit is located at therear of right hand cylinder head. The governor is set to limit theengine speed to 2650 rpm under full load and should not be tamperedwith except by ordnance maintenance personnel.

Two inlet and two exhaust valves are provided for each cylinderand are operated by overhead camshafts, two in each cylinder head,one shaft operating the intake valves and the other operating theexhaust valves. Special non-adjustable tappets are used. Theclearance of 0.023-inch to 0.028-inch is determined during manufacture, and should require no attention other than checking as bothintake and exhaust valve ports are provided with steel inserts. Thetappet clearance should remain constant over a long period of operation. In the event the clearance becomes too small, it will be necessary to grind off valve stem to obtain correct clearance.

The intake manifold is cast in the cylinder head,and is open at each end where the front and rear carburetors areattached. Two exhaust manifolds are used and are bolted directlyto right and left side of the block and connected to each other atthe rear. Each exhaust manifold is connected to a separate exhaust pipe.

(1) Open the door at the rear of the engine compartment. Toopen this door all the way raise the radiator air baffle and allow itto rest on top of the door after the door is open.(2) Remove plug in engine compartment floor plate.(3) Open drain valve at bottom of water pump and drain throughthe hole in floor plate.50

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POWER UNIT AND ESSORIES(4) Remove engine compartment floor plate.(5) Drain engine oil pan.(6) Remove the nutssecuring water pump, disconnect the water

pump hose and remove the waterpump.(7) Remove radiator top hose and two condenser tankhoses.(8) Open the grilled engine compartment doors and remove thefront and rear hatch plates.(9) Disconnect fanbelts on each side of engine by loosening ac

cessory drive adjustments.(10) Remove four bolts in each fan shroud.(11) Remove fan assemblies from engine compartment.(12) Turn off battery master switch.(13) Disconnect starter lead at starter.(14) Disconnect generator armature and generator field leadat generator.(15) Disconnect oil level indicator on left side of the oil pan.(16) Disconnect oil pressure lead at right rear of the crankcase.(17) Disconnect two magneto ground wires at the magnetos.(18) Disconnect degasser wires from carburetors and degasser

conduit from engine.(19) Disconnect the right and left accessory drive shafts fromtherespective accessorydrive housings.(20) Remove theaccessory drive housings.(21) Disconnect the tachometer from left cylinder head.(22) Disconnect the clutch release rod at the clutch housing.(23) Remove the circular spacerplate around the clutch housing.(24) Shut off the fuel valves and disconnect the fuel line fromthe fuel pump.(25) Disconnect throttle control rod.(26) Disconnect air cleaner outlet pipes atthe air cleaners.(27) Disconnect driveshaft bolts at clutch shaft flange(28) Remove bolts securing the engine to the four support

brackets.(29) Disconnect exhaust pipe from exhaust manifold.(30) Secure lifting sling to four engine lifting eyes.(31) Remove engine from hull.

Reverse the sequence of removal operations.The starting motor is a 24 volt type mounted onthe right side of flywheel housing and its power is transmitted tothe engine through an automatic drive. A solenoid switch located

on right forward side of bulkhead closes the electrical circuit of thestarting motor when the starter buttonon the instrument board is5

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MEDIUM TANK M4A3

pressed. Rotation of the starter motor shaft causes the pinion ofthe automatic drive to advance and mesh with the flywheel. Aftertheengine starts and the fly wheel speed exceeds that of the startingmotor, the pinion releases from the flywheel automatically. Thestarting motor bearings do not require lubricating.Disconnect the two starter wires and remove threenuts which hold thestartermotor tothe crankcase flange and removethe starter.

Reverseabove procedure. Refer to the wiringdiagram figure 19 .

A special Ford tank generator model GA A isused. The generator is 30 volt, 50 ampere capacity andcurrentcontrol isobtained by a generator regulator mounted underneathfloor of turret. The generator is mounted on the accessory drivehousinganddriven bythe accessory shaft.Generators are properly lubricated at engineoverhaul periods and should not require additional lubrication be

tween overhaul periodsA faulty generator should be replaced as follows:

.(1) Turn off battery master switch.(2) Disconnect wiresfrom armature and field terminals.(3) Disconnect flexible conduit.(4) R emove the four nuts which hold thegeneratorto accessorycase and remove the generator.

Reverse procedure asoutlined above. Refer tothe wiring diagram figure 19 .

The oil pump is ageartype driven from the camshaft driveshaft. The oil pump should require no periodical check.Remove engine compartment floor plate. R emovethe four nuts holding the oil pump to the crankcase and re movethe pum p.

Secure the pump to the crankcase with the fournuts. Replace theengine compartment floor plate.

The oil filter is the motorized Cuno type locatedonthe right side of the oil pan at the rear accessible through therear door.

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b. Operation check. To check the operationof the filter, reversethe manual turning nut andturn the engine over withthe starter.The manual turning nut will rotate if the filter is operating. Afterthe check is made, replace the manual turning nut in original position and secure with lockwire.c. R emoval. Unscrew the six cap screws securing the motor andfilter element to the crankcase, and remove motor andfilter element.(1) Clean the filter body before installing the motorand filteringelement.(2 ) Replace the motor and filter element and secure with the six capscrews.

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Section VII

REFERENCESParagraph

Standard nomenclature lists........................................................ 38Technical and field manuals..... .... ..............- .,................. 39Miscellaneous publications ............... ........................................... 40

Gun, cal. .30, Browning, M1919A4, fixed and flexible bowmounts ............................... ............................................... SN L A-6Gun, sub-machine, cal. .45, Thompson, M 1928A1............ SN L A-32Gun,machine, cal. .50, Browning, M2, heavy barrel, fixedand flexible and ground mounts................ .......... ......... SNL A-39Materiel, 75-mm, tank gun, M2, M S.................................... SNL C-34Tank, medium, M4A2 in preparation)......................... SN L G-104Vol. VIII

75-mm tank gun materiel.................................................... TM 9-307Cleaning, preserving, and lubricating materials... .. .. .. TM 9-850Browningmachine gun, cal. .50, all types........................ TM 9-1225Stabilizers, all types.............................................................. TM 9-1799Fire prevention, safety precautions, accidents...... ....... TM 10-360Sheet metal work, body, fender and radiator repairs...... TM 10-450Echelon system of maintenance........................................ TM 10-525Automotive lubrication ............... ....................................... TM 10-540Motor transport inspection............. ..................................... TM 10-545Automotive electricity ....................... ................................. TM 10-580Defense against chemical attack...................................... FM 21-40Gun, sub-machine, cal. .45, Thompson, M1928A1. FM 23-40Gun, cal. .30, Browning, M1919A4.................................... FM 23-50

Military motor vehicles........................................................ A R 850-1 5Storageof motor vehicle equipment.................................... AR 850-18Detailed lubrication instructions for ordnancemateriel ..........................................................................OFSB 6 Series

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INDEXA PageNo.

Accessories See Power unitandaccessories)

Accessory speeds data on 39Adjustments, idle fuel................47-49Air cleaners

Descriptionof.............................. 49Lubrication of ............................ 26MaintenanceCleaning filter element.......... 49

Dailyservicing........................ 49Removal andinstallation of.... 50Air outlet rubber hose connec

tions, inspection of................... 26Air space in tank............................ 31Ammeter, location and function

of .................................................. 14Armament ...................................... 3-6Armor thickness, data on.............. 6Auxiliary generator, lubricationof..................................................26-27

BBatteryCharging .................................... 3Checking and cleaning.............. 31Electrical power shut off at....15-17Faults, indication of by ammeter andvoltmeter.............. 14Gravityof checking......---...-..- 40

Battery master switchLocation andoperation of........15-17Battery water, replenishing.......... 31Blackout driving light switch,functionof and caution for...... 12Bosch magnetos, operation of...... 13Brackets, location of...... .. ........ 34Brakes, location and descriptionof

Parkingbrake ............................ 8Service brakes .......... . . . .......... 8Cable C

Arrangement of for shorthitch .. . . ...... 22Care of while tracking.............. 22Precaution while towing.......... 21Capacity of hydraulicoil tank.... 27

CCont d Page oCarburetor

Data on................................... 39Description of ........ .............. .. 47Idle adjustment of..........47-49Removal and installation of...... 49

Castings, detecting cracks in... 28Characteristics of engine SeeData, tabulated)Charts, lubrication

Powerdriveunits...................... 24 Suspension .................................. 25Checks See Inspection)Circuit breakers, location andfunctionof ...................... ......... 13Cleaning

Battery and compartment........ 31Filterelement ........................ 49Floors .......................................... 31Transmission filler .................... 26ClearanceCable andtracks........................ 22Clutchpedal, inspection of........ 29Steering mechanism ................. . 29Tappet ........................................ 50Valve .......................................... 39

Clock, location of....................... 13Clutch

Location and operation of........ 8Precautions in operating.......... 20Cold weather starting.................... 12

Communication, data on................ 6Compartment lightrheostat........ 13Compression ratio ........................ 39Controls, general information on8-18

Ammeter .................................... 14Battery masterswitch.........15-17Blackout drivinglight switch.. 12Brakes ........................................ 8Circuitbreakers ........................ 13Clock .............. .................. 13Clutch .......................................... 8Engine temperaturegage........ 15Fuelcut-out.... 13GagesEngine temperature ...... 15Fuel level .... ....... 15O il level .................................. 15

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CContd Page No.ControlsCont d

Oil pressure ............................ 14Oil temperature .................... 15Gear shifting ..............................17-18Ignition switch .......................... 13Light switches .. ........................ 8-12Primer ........................................12-13Rheostat, compartment light.... 13Selector switch ............... ........... 15Signals, low oi l pressure............ 15Sparkcontrol .............................. 8Speedometer .............................. 15Starter switch .. .......................... 12Steering levers .......................... 8Tachometer ................................ 14Throttle controls ........................ 8Utility outlet .............................. 8Voltmeter .... ................................ 14

Coolant in engine, temperatureof .. .......... .. .......... .. .......... ........... .. . 17Cooling

System, description of............ .. 15Valves and engine...................... 22Cracks, detection of........................ 28

CrankcaseDescription of.............................. 34Lubrication of .. ............ ............ .. 26

Crankshafts, overhead .................. 34Crew, number of............................ 7Cylinder block description of...... 34Cylinder (s)

Numbering of.............................. 39Trouble fromexcessivepriming 13

Data, tabulatedArmament .. ........... ............ ......... 3-6Armor thickness........................ 6Communication ..........................Crew ............................................ 7Dimensions ................................ 3Engine ........................................ 3,39Fuel and oil.... .......... ....................Performance of engine.............. 6-7Periscopes .................................. 6Tracks .. ......... ............ ............ .. ... 7Turret .......................................... 6Weight ........................................ 3

Degasser, use of.............................. 47

DCont d Page No.Description

Air cleaners ................................ 49Carburetors ................................ 47Fuel pump.................................... 47Generator .................................... 52Magnetos .. .................................. 42Manifolds .................................... 50Oil filter...................................... 52Oil pump...................................... 52Power unit ..................................34-39Spark plugs ................................ 46Starting motor............................51-52Turret .. ... .......... .............. .......... .. . 3Vehicle ........... ............ ............ ..... 3

DimensionsEngine .......... ............ ............ .... 39Vehicle ...... .......... .............. .......... 3

DrainingAir cleaners................................ 26Crankcase .................................. 26Floors .......................................... 31Gear cases.................................... 26Hydraulic oil tank...................... 27

Electrical generating system,auxiliary .. .................................. 3Electrical power, shut off..............15-17Engine

Data, tabulated ........................ 3, 39Description of ............................34-39InspectionDuring operation.................... 29Prestarting ............................28-29Lubrication

Additional instructions onindividual units andparts..23-27General instructions for........ 23Generators .............................. 23Guide .. .................................... 23Reports and records.............. 23Mounting of on vehicle.............. 34Overheating, causes of.... .......... 42Performance .............................. 6-7Indications of ........................ 21Priming, excessive...................... 13Replacement ..............................50-51Speed, regulation of by governor ....... .......... .. .......... ...........14 50Starting instructions................ 18

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EContd Page No.EngineCont'd

Stopping .. ...................... ....... ....... 22Toggle switch, use of.............. 13

Temperatureof ................ .......... 15Test ..............................................18-20Trouble shooting........................40-42See lso Power unit and ac

cessories)Engine temperaturegage, loca

tion and use of............................ 15Engine troubleshooting

Failure toturnover.................. 40Turning over and failure tostart ........................................40-41Unevenrunning........................41-42

Equipment for towing.................. 21Exhaust manifolds ........................ 50

Failure of enginetoturnandtostart .................. ........................40-41Fans ................................................ 34

Filter element,cleaning................ 49Filters (See Oil AlterandFuel

Alter)Fire hazard, caution in eliminat-

ing 31Firingorder.................................. 3 )Fittings, lubricationof...... ...........23-26Flooding,cause of... ...................... 13Floors, draining and cleaning...... 31Front sideofengine

Definition of............................... 3 )Illustration of.............................. 38

FuelData on........................................ 0Use ofrecommended grade of 42

Fuel cut-out,locationand operation of.......................................... 13FuelAlter lubrication of.............. 27Fuel level gage, locationanduseof .................................................. 15Fuel pump

Description of............................ 47Maintenanceof ......................... 47Removal and installation of...... 47

G PageNo.Gage(s)

Enginetemperature .................. 15Fuel level .................................... 15Indicationof engine performanceby.................................... 21Inspectionofduring operation 29Oil level ...................................... 15Oil pressure .............................. 15Oil temperature.. ...... ................ 14

Gas tank cap, precaution beforeremoving .................................... 31

Gearcases lubrication of.............. 26Gearshift leverLocationof and equipmentfor 17

Use of in shifting......................17-18Gearshifting

Description 17Operation ..................................17-18Instructionsfor....................20-21

Generator,auxiliary See Auxiliarygenerator)Generator regulator,use of........ 14Generator(s)

Description of .. ... ..................... .. 52Lubrication of............................23 52Removal and installationof...... 52

Governor, location anduse of...... 50Groundclearance ............._........... 3Grousers .......................................... 21Guide lubrication.... ....... .............. . 23Gun(s)Armament forvehicle.............. 3-6Elevation of duringprestart-

ing inspection ...................... 28

Horsepower, engine...................... 39Hot weather, operation in............ 31Hydraulic oil tank,lubrication of 27

Idle fueladjusting screws............47-49Idlingtheengine............................ 20Ignition

Timing ........................................ 46Checking ................................42-45Trouble ........................................ 41Wires,damaged.......................... 42

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TM9759INDEX

IContd PageNo.Ignitionswitch, locationandoperationof.................................... 13Indirectvision devices.................. 6Induction system, leaks in.......... 41Inspection s)Afteroperation..........................30-31Air outlet rubberhoseconnection .......

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