269630396 systems operation testing and adjusting cat 740 articulated

RENR5134-01July 2001

Systems OperationTesting and Adjusting740 Articulated Truck Power TrainAXM1-Up (Machine)

i01097883

Important Safety InformationMost accidents that involve product operation, maintenance and repair are caused by failure toobserve basic safety rules or precautions. An accident can often be avoided by recognizing potentiallyhazardous situations before an accident occurs. A person must be alert to potential hazards. Thisperson should also have the necessary training, skills and tools to perform these functions properly.

Improper operation, lubrication, maintenance or repair of this product can be dangerous andcould result in injury or death.

Do not operate or perform any lubrication, maintenance or repair on this product, until you haveread and understood the operation, lubrication, maintenance and repair information.

Safety precautions and warnings are provided in this manual and on the product. If these hazardwarnings are not heeded, bodily injury or death could occur to you or to other persons.

The hazards are identified by the “Safety Alert Symbol” and followed by a “Signal Word” such as“DANGER”, “WARNING” or “CAUTION”. The Safety Alert “WARNING” label is shown below.

The meaning of this safety alert symbol is as follows:

Attention! Become Alert! Your Safety is Involved.

The message that appears under the warning explains the hazard and can be either written orpictorially presented.

Operations that may cause product damage are identified by “NOTICE” labels on the product and inthis publication.

Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. Thewarnings in this publication and on the product are, therefore, not all inclusive. If a tool, procedure,work method or operating technique that is not specifically recommended by Caterpillar is used,you must satisfy yourself that it is safe for you and for others. You should also ensure that theproduct will not be damaged or be made unsafe by the operation, lubrication, maintenance orrepair procedures that you choose.

The information, specifications, and illustrations in this publication are on the basis of information thatwas available at the time that the publication was written. The specifications, torques, pressures,measurements, adjustments, illustrations, and other items can change at any time. These changes canaffect the service that is given to the product. Obtain the complete and most current information beforeyou start any job. Caterpillar dealers have the most current information available. For a list of the mostcurrent publication form numbers available, see the Service Manual Contents Microfiche, REG1139F.

When replacement parts are required for thisproduct Caterpillar recommends using Caterpil-lar replacement parts or parts with equivalentspecifications including, but not limited to, phys-ical dimensions, type, strength and material.

Failure to heed this warning can lead to prema-ture failures, product damage, personal injury ordeath.

3Power Train

Table of Contents

Table of Contents

Systems Operation Section

Graphic Color Codes ............................................ 4General Information .............................................. 5Torque Converter ................................................. 6Transmission Planetary ......................................... 8Output Transfer Gears ......................................... 9Interaxle Differential .............................................. 11Differential (Front and Rear Axle) ......................... 13Differential (Center Axle) ....................................... 15Final Drive ............................................................ 18Power Train Hydraulic System ............................. 19Transmission Hydraulic Control ........................... 23Power Train Electronic Control System ................. 24Output Transfer Gears Lubrication System ........... 28Pressure Control Valve (Transmission) ................. 30Selector and Pressure Control Valve(Transmission) ..................................................... 37

Rotary Actuator (Transmission) ............................ 40

Testing and Adjusting Section

TroubleshootingMachine Preparation for Troubleshooting ............. 42General Troubleshooting Information .................... 42Visual Inspection ................................................... 43Operational Checks .............................................. 44Torque Converter Troubleshooting ........................ 45Transmission Planetary Troubleshooting .............. 47Interaxle Differential Troubleshooting .................... 52Differential Troubleshooting .................................. 53

Testing and AdjustingPower Train Pressures .......................................... 55Transmission Hydraulic Control - Test and Adjust .. 73Transmission Shift Points - Test ............................ 82Interaxle Differential - Test .................................... 84Differential - Test ................................................... 85

Index Section

Index ..................................................................... 88

4Power TrainSystems Operation Section


i01481554

Graphic Color CodesSMCS Code: 4000

g00771291Illustration 1

(A) Red ........................... Pump discharge pressure

(B) Red Stripes and WhiteStripes .......................... First pressure reduction

(C) Red Dots ................ Second pressure reduction

(D) Orange ............................. Pilot system pressure

(E) Orange Stripes and WhiteStripes .............. Reduced pilot system pressure

(F) Blue .................................................. Blocked oil

(G) Green .. Suction oil, return oil, and case drain oil

(H) Yellow ..................................... Moving parts andactivated valve sections

(I) Purple ........................................ Pressurized gas

(J) Gray ............................... Cutaway sections, andnon-activated valve sections

5Power Train


i01563882

General InformationSMCS Code: 3030


(1) Engine(2) Torque converter(3) Transmission planetary(4) Wheel and final drive(5) Differential and bevel gear(6) Output transfer gears and case

(7) Drive shaft(8) Through hitch drive shaft(9) Drive shaft(10) Differential and bevel gear(11) Drive shaft(12) Differential and bevel gear

(13) Wheel and final drive(14) Wheel and final drive(15) Differential(16) Front drive shaft(17) Main drive shaft

Tractor Arrangement

The engine flywheel drives torque converter (2).The torque converter has an integral lockup clutch.The lockup clutch for the torque converter allowsthe machine to operate in torque converter drive orin direct drive.

Torque converter (2) is located within the housingfor the transmission planetary which is bolteddirectly to the engine. Transmission planetary (3)contains seven hydraulically actuated clutches. Theseven hydraulically actuated clutches give sevenforward speeds and one reverse speed.

Main drive shaft (17) transmits torque to outputtransfer gears and case (6). Differential (15) islocated in output transfer gears and case (6), whichis connected to front drive shaft (16) and drive shaft(7). Front drive shaft (16) is connected to differentialand bevel gear (5). Drive shaft (7) is connectedhitch drive shaft (8).

Differential and bevel gear (5) transfers drive towheel and final drives (4) for the front axle.

Trailer Arrangement

Through hitch drive shaft (8) transmits torque todrive shaft (9). The drive shaft transfers drive todifferential and bevel gear (10).

Differential and bevel gear (10) transfers drive towheel and final drives (14) for the center axle anddrive shaft (11).

Drive shaft (11) transmits torque to differential andbevel gear (12).

Differential and bevel gear (12) transfers drive towheel and final drives (13) for the rear axle.


i01523695

Torque ConverterSMCS Code: 3101


(1) Housing(2) Turbine(3) Stator(4) Shaft

(5) One-way clutch(6) Impeller(7) Lockup Clutch(8) Hub

The torque converter is driven by the engineflywheel. The torque converter consists of impeller(6), turbine (2), lockup clutch (7), and stator (3)which incorporates one-way clutch (5). The lockupclutch permits the machine to operate in directdrive in order to keep the power loss at a minimum.The one-way clutch holds the stator when torqueconverter drive is used. The one-way clutch allowsthe stator to turn freely when direct drive is used.

The torque converter housing is fastened to theflywheel housing for the engine. Shaft (4) connectsthe torque converter to the transmission planetarygroup.

The engine flywheel turns rotating housing (1) andimpeller (6). The impeller directs oil onto the bladesof turbine (2). This causes the turbine to turn. Theturbine directs the oil onto stator (3). This causesthe stator to try to turn in the opposite directionof the turbine. The movement of the stator causesthe rollers of one-way clutch (5) to move betweenstator (3) and the carrier for the stator. The actionof the one-way clutch keeps the stator from rotatingin the opposite direction to the turbine. The statornow directs most of the oil back to the impeller.The remainder of the oil goes out of the torqueconverter. The oil, that goes back to the impellerfrom the stator, moves in the same direction as therotation of the impeller. Since this oil is moving inthe same direction as the impeller, the torque outputfrom the torque converter is multiplied.

Turbine (2) turns hub (8). The hub turns shaft (4).Power is sent through the shaft to the transmissionplanetary group.

7Power Train


Lockup clutch (7) is part of the torque converter.The lockup clutch is located between the engineflywheel and the turbine. The lockup clutch isengaged under the following conditions: sufficientinput speed to the transmission planetary group,sufficient oil pressure in the transmission planetarygroup, and sufficient engine rpm. When thelockup clutch is engaged, the impeller and theturbine turn at the same speed as the engine andthere is no loss of power in the torque converter.The connection between the engine and thetransmission planetary group is now direct.

Torque converter drive is available in the first gearand reverse gear. The lockup clutch provides directdrive once the transmission speed and the enginespeed are matched.

Direct drive is provided in all the higher gears. Thelockup clutch is disengaged during transmissionshifts in order to allow a smooth transition betweengears.

The input speed of the torque converter is measuredat the engine flywheel. This speed is the samespeed as the engine output speed. The outputspeed of the torque converter is measured at theplanetary transmission. This speed is the samespeed as the transmission input speed.


i01523914

Transmission PlanetarySMCS Code: 3160


(1) Clutch 1(2) Clutch 2(3) Clutch 3(4) Clutch 4(5) Clutch 5

(6) Clutch 6(7) Clutch 7(8) Sensor (output speed)(9) Output yoke(10) Shaft (input from torque converter)

The planetary transmission has seven forwardspeeds and one reverse speed. At lower groundspeeds, FIRST speed uses torque converter drive.At higher ground speeds, FIRST speed uses directdrive. As the ground speed increases in FIRSTspeed the lockup clutch of the torque converterengages. This provides FIRST speed with directdrive. The torque converter is always in direct drivefor speeds SECOND through SEVENTH, but thereis a short period of torque converter drive whenthe clutches engage in the planetary transmission.Only torque converter drive is used when REVERSEspeed is selected. The torque converter lockupclutch is disengaged during transmission shifts inorder to provide smooth shifts. Table 1 shows theclutches that are engaged for each speed.

Table 1

SPEED SELECTION

SPEED ENGAGED CLUTCHES

NEUTRAL 1

REVERSE speed 3 & 7

FIRST speed 2 & 6

SECOND speed 1 & 6

THIRD speed 3 & 6

FOURTH speed 1 & 5

FIFTH speed 3 & 5

SIXTH speed 1 & 4

SEVENTH speed 3 & 4

9Power Train


The planetary transmission consists of two rotatingclutches, five stationary clutches, and five planetaryunits. This provides seven forward speeds and onereverse speed. No. 3 clutch (3) and No. 4 clutch (4)are the rotating clutches.

The planetary transmission is bolted to the torqueconverter housing. Shaft (10) is part of the torqueconverter, and the shaft transmits the torque to theplanetary transmission. Output yoke (9) from theplanetary transmission is bolted to the main driveshaft. The main drive shaft connects the planetarytransmission with the output transfer gear.

Sensor (8) measures the output speed of theplanetary transmission. There are two sensorsin order to provide a backup in the event of afailure. The sensors send information about thetransmission output speed to the ECM (ElectronicControl Module).

i01575760

Output Transfer GearsSMCS Code: 3159


(1) Input Shaft(2) Differential(3) Shaft(4) Gear

(5) Idler Gear(6) Gear(7) Output Yoke(8) Shaft

(9) Gear(10) Gear(11) Output Yoke(12) Solenoid and Relief Valve


Power is transmitted to the output transfer gearsfrom the transmission planetary group via a driveshaft to input shaft (1). The input shaft is splinedto interaxle differential (2) that splits the torquebetween the front and the rear axles. Torque for thefront axle is transmitted from the differential alongshaft (3) to gear (4). An idler gear (5) transfersthis torque to gear (6) in the bottom of the outputtransfer gear case. Gear (6) is splined to the outputyoke (7).

Torque for the rear axles is transmitted from thedifferential along shaft (8) to gear (9). Gear (9) ismeshed with gear (10) which is splined to outputyoke (11).


This is a view of the solenoid and relief valve from below themachine.

Solenoid and relief valve (12) controls the lubricationoil for the output transfer gears. The solenoid andrelief valve also controls the interaxle differentialand the axle differentials.

11Power Train


i01524199

Interaxle DifferentialSMCS Code: 3287


(1) Input shaft(2) Shaft(3) Planetary gear(4) Differential housing(5) Clutch pack

(6) Piston(7) Rotating housing(8) Output shaft(9) Output shaft(10) Gear

(11) Gear(12) Sun gear(13) Planetary gear(14) Sun gear(15) Hub

Torque from the transmission planetary entersthe output transfer gears, and flows directly todifferential housing (4). The torque is transmittedthrough the interaxle differential to output shaft (8)and output shaft (9).

The interaxle differential allows the torque from thetransmission planetary to be divided between thefront axle and the two rear axles.

The front axle receives a smaller proportion of thetorque than the center and rear axles. This preventsexcess torque from being transmitted to the frontaxle.

The distance from the axis of rotation of differentialhousing (4) to the axis of planetary gears (3) isgreater than the distance to the axis of planetarygears (13).

Planetary gears (3) transfer the torque fromdifferential housing (4) to output shaft (9) andplanetary gears (13) transfer the torque fromdifferential housing (4) to output shaft (8).

The torque that is transmitted to output shaft (9) isgreater than the torque that is transmitted to outputshaft (8).

Output shaft (9) transmits the torque to the two rearaxles and output shaft (8) transmits the torque tothe front axle.

The torque that is transmitted to the two rear axlesis greater than the torque that is transmitted to thefront axle. 40% of the torque is transmitted to thefront axle and 60% of the torque is transmitted tothe center and the rear axle.


If the machine was operated on a hard surface withequal traction at each wheel, turning the machinewould cause torsional stresses in the power train.This could reduce the service life of componentsin the power train.

The interaxle differential transmits drive to the frontand rear axles at equal speeds when the machineis travelling straight. The interaxle differential alsotransmits drive to the front and rear axles at differentspeeds when the machine is turning. Torque input ismaintained at each axle throughout each operation.

The interaxle differential responds to the differencein resistance between the front wheels and thecenter and rear wheels. This is carried out ina similar manner to the response of the axledifferentials to the speed difference between theinner wheels and the outer wheels.

The interaxle differential is equipped with a lockupclutch. The lockup clutch is activated by a floormounted switch. The lockup clutch will neutralizenormal interaxle differential operation and transferdrive to all three axles regardless of the groundconditions or the rolling resistance at each wheel.

The interaxle differential consists of an input shaft(1) which is connected to differential housing (4).Differential housing (4) contains two pairs of threeevenly spaced shafts (2). The shafts are used tosupport two planetary gear sets (3) and (13). Bothplanetary gear sets are in constant mesh with eachother and each of the gears is free to rotate aroundshafts (2).

Planetary gear set (3) is in constant mesh with sungear (14) which is installed onto output shaft (9)for the output drive to the trailer. Planetary gear set(13) is in constant mesh with sun gear (12) whichis installed onto output shaft (8) for the output driveto the tractor.

When the machine is moving in a straight directionwith equal ground resistance at each wheel thedifferential housing (4), planetary gears (3) andplanetary gears (13) rotate as a unit.

When the machine is turning, the turning radiuschanges at the front wheels and at the rear wheels.Planetary gears (3) and (13) rotate around shafts(2) as sun gear (14) for the drive to the trailer slowsdown.

If wheel spin occurs at the front of the machine,drive to the center axle and drive to the rear axlewould be reduced to a degree that would stopthe machine. In this event, engaging the interaxledifferential lock would restore drive to all axles.The differential effect is cancelled by locking thedifferential housing to the output shafts.

When the operator engages the differential lock, oilpressure is transmitted by the solenoid and reliefvalve to rotating housing (7). The oil pressure insiderotating housing (7) acts on piston (6) which forcesthe piston against clutch pack (5). Hub (15) anddifferential housing (4) are then connected. Bothplanetary gear sets and both sun gears are lockedin position. The differential effect is cancelled. Shaft(8) and shaft (9) will rotate at the same speed.

When the operator disengages the differential lock,oil pressure is relieved at piston (6). This allowsclutch pack (5) to disengage. Differential housing(4) and hub (15) are disconnected and the interaxledifferential effect is restored.

13Power Train


i01551675

Differential (Front and RearAxle)SMCS Code: 3258-RE; 3258-FR


Differential

(1) Bevel pinion shaft(2) Oil supply tube(3) Chamber(4) Piston(5) Pressure plate(6) Rotating plate

(7) Friction disc(8) Hub assembly(9) Axle shaft(10) Side gear(11) Differential case(12) Spider

(13) Pinion gear(14) Axle shaft(15) Side gear(16) Bevel gear

A differential is an arrangement of gears whichenables one shaft to drive two shafts with equaltorque. The differential also allows the two shafts torotate at different speeds.

The differential in an axle enables drive to bemaintained to both wheels through separate axleshafts when the machine is turning. The wheel onthe inside of the turn will travel a shorter distancethan the wheel on the outside of the turn. Thiscauses the wheel on the inside of the turn to slowdown while the wheel on the outside of the turnspeeds up.

In adverse ground conditions, one or more ofthe wheels may lose traction. The action of thedifferential will result in a loss of drive as thedifferential allows the torque to be transmitted alongthe path of least resistance, which will be the wheelthat is slipping.

The differential in each axle can be locked inadverse conditions. Locking the differential providesdirect drive to all the wheels at the same speedregardless of the resistance due to traction.


A differential divides the power that is sent to themachine wheels. During a turn, the inside wheelturns at a slower rate than the outside wheel. Thedifferential still sends the same amount of torqueto each wheel. Each differential has a differentiallock. The main component of the differential lock isthe clutch pack. When the differential lock switchesare engaged, the clutch pack connects one axleshaft to the differential case. Both axle shafts areconnected in order to form a solid axle with nodifferential effect.

The inside components of the differential receivelubrication from the oil that is inside the axlehousing.

Bevel pinion shaft (1) is in constant mesh with bevelgear (16). The bevel pinion shaft and the bevelgear provide a gear reduction and a change in thedirection of drive by 90�.

Differential case (11) is attached to bevel gear(16). The differential case holds spiders (12). Fourpinion gears (13) are free to rotate around thespiders. Side gears (10) and (15) are mounted inthe differential case. The side gears are meshedwith the pinion gears. Axle shafts (9) and (14) aresplined into the side gears.

When the bevel gear (16) is turned by bevel pinionshaft (1), differential case (11) is also turned. Ifthe resistance between each of the road wheelsis equal, pinion gears (13) will not rotate aroundspiders (12). The pinion gears will turn with thespiders. The pinion gears will turn the side gearswith equal speed and equal torque.

When the machine is turning, the wheel that is onthe inside of the turn will travel a shorter distancethan the wheel on the outside of the turn. Thiscauses the wheel on the inside of the turn to slowdown while the wheel on the outside of the turnspeeds up.

The axle shaft on the inside of the turn and the sidegears on the inside of the turn slow down. Thiscauses the pinion gears to rotate on the spiders.

The wheel, the axle shaft and the side gear onthe inside will slow down as the machine turns.The wheel, the axle shaft and the side gear on theoutside will speed up in proportion to the insidewheel. The differential between the speed of thetwo wheels is taken up by the rotation of the bevelgears around the spiders. Both wheels are drivenwith equal force, but at different speeds.

When one wheel has more traction than the otherwheel, the torque travels by the path of leastresistance to the wheel that has less traction. Thewheel with less traction will spin and the wheelthat has traction will be stationary. In this condition,the machine will lose drive. A differential lock isprovided in order to prevent loss of drive in adverseconditions.

Differential Lock Operation

The axle differential lock should be engaged whenthe machine is being operated on a loose surfaceor a soft surface. The axle differential lock shouldalso be engaged if wheel spin is experienced andadditional traction is required. Damage can occur todrive line components through a buildup of torsionalstress, if operating the machine on a hard surfacewith the axle differential lock engaged. The machineshould only be driven in a straight line when theaxle differential lock is engaged.

When the differential lock switches are operated,oil pressure is transmitted through oil supply tube(2) into chamber (3). Piston (4) is offset againstpressure plate (5) which forces rotating plates (6)and friction discs (7) together, locking axle shaft (9)to hub assembly (8). This prevents side gear (10)from rotating inside differential case (11). Piniongears (13) stop revolving and this causes side gear(15) and axle shaft (14) to lock. Both axle shaftsnow rotate at the same speed as the bevel gearand differential case.

15Power Train


i01515596

Differential (Center Axle)SMCS Code: 3258-CE


Differential

(1) Bevel pinion shaft(2) Gear(3) Oil supply tube(4) Chamber(5) Piston(6) Pressure plate

(7) Rotating plate(8) Friction disc(9) Hub assembly(10) Axle shaft(11) Side gear(12) Differential case

(13) Spider(14) Pinion gear(15) Axle shaft(16) Side gear(17) Bevel gear(18) Differential carrier

A differential is an arrangement of gears whichenables one shaft to drive two shafts with equaltorque. The differential also allows the two shafts torotate at different speeds.

The differential in an axle enables drive to bemaintained to both wheels through separate axleshafts when the machine is turning. The wheel onthe inside of the turn will travel a shorter distancethan the wheel on the outside of the turn. Thiscauses the wheel on the inside of the turn to slowdown while the wheel on the outside of the turnspeeds up.

In adverse ground conditions, one or more ofthe wheels may lose traction. The action of thedifferential will result in a loss of drive as thedifferential allows the torque to be transmitted alongthe path of least resistance, which will be the wheelthat is slipping.

The differential in each axle can be locked inadverse conditions. Locking the differential providesdirect drive to all the wheels at the same speedregardless of the resistance due to traction.


A differential divides the power that is sent to themachine wheels. During a turn, the inside wheelturns at a slower rate than the outside wheel. Thedifferential still sends the same amount of torqueto each wheel. Each differential has a differentiallock. The main component of the differential lock isthe clutch pack. When the differential lock switchesare engaged, the clutch pack connects one axleshaft to the differential case. Both axle shafts areconnected in order to form a solid axle with nodifferential effect.

The inside components of the differential receivelubrication from the oil that is inside the axlehousing.

Bevel pinion shaft (1) is in constant mesh with bevelgear (17). The bevel pinion shaft and the bevelgear provide a gear reduction and a change in thedirection of drive by 90�.

Differential case (12) is attached to bevel gear(17). The differential case holds spiders (13). Fourpinion gears (14) are free to rotate around thespiders. Side gears (11) and (16) are mounted inthe differential case. The side gears are meshedwith the pinion gears. Axle shafts (10) and (15) aresplined into the side gears.

When the bevel gear (17) is turned by bevel pinionshaft (1), differential case (12) is also turned. Ifthe resistance between each of the road wheelsis equal, pinion gears (14) will not rotate aroundspiders (13). The pinion gears will turn with thespiders. The pinion gears will turn the side gearswith equal speed and equal torque.

When the machine is turning, the wheel that is onthe inside of the turn will travel a shorter distancethan the wheel on the outside of the turn. Thiscauses the wheel on the inside of the turn to slowdown while the wheel on the outside of the turnspeeds up.

The axle shaft on the inside of the turn and the sidegears on the inside of the turn slow down. Thiscauses the pinion gears to rotate on the spiders.

The wheel, the axle shaft and the side gear onthe inside will slow down as the machine turns.The wheel, the axle shaft and the side gear on theoutside will speed up in proportion to the insidewheel. The differential between the speed of thetwo wheels is taken up by the rotation of the bevelgears around the spiders. Both wheels are drivenwith equal force, but at different speeds.

When one wheel has more traction than the otherwheel, the torque travels by the path of leastresistance to the wheel that has less traction. Thewheel with less traction will spin and the wheelthat has traction will be stationary. In this condition,the machine will lose drive. A differential lock isprovided in order to prevent loss of drive in adverseconditions.

Differential Lock Operation

The axle differential lock should be engaged whenthe machine is being operated on a loose surfaceor a soft surface. The axle differential lock shouldalso be engaged if wheel spin is experienced andadditional traction is required. Damage can occur todrive line components through a buildup of torsionalstress, if operating the machine on a hard surfacewith the axle differential lock engaged. The machineshould only be driven in a straight line when theaxle differential lock is engaged.

When the differential lock switches are operated,oil pressure is transmitted through oil supply tube(3) into chamber (4). Piston (5) is offset againstpressure plate (6) which forces rotating plates (7)and friction discs (8) together, locking axle shaft(10) to hub assembly (9). This prevents side gear(11) from rotating inside differential case (12). Piniongears (14) stop revolving and this causes side gear(16) and axle shaft (15) to lock. Both axle shaftsnow rotate at the same speed as the bevel gearand differential case.

Center Axle Through Drive


The center axle on the 740 features a through drivein order to transmit drive to the rear axle.

17Power Train



(1) Bevel pinion shaft(2) Gear

(17) Bevel gear(19) Gear assembly

Drive is input to the axle from the drive shaft to gearassembly (19). Gear assembly (19) is meshed withgear (2) on bevel pinion shaft (1). This provides thedrive to bevel gear (17).

Drive to the rear axle is carried by gear assembly(19) to an output shaft that connects to the driveshaft to the rear axle via a universal joint.


i01515331

Final DriveSMCS Code: 4050


Final Drive (Front and Center Axle)

(1) Wheel(2) Ring gear(3) Planetary carrier(4) Spindle(5) Axle shaft(6) Sun gear(7) Hub(8) Gear(9) Wheel bearings(10) Seals(11) Brake (Front axle and center axle)


Final Drive (Rear Axle)

(1) Wheel(2) Ring gear(3) Planetary carrier(4) Spindle(5) Axle shaft(6) Sun gear(7) Hub(8) Gear(9) Wheel bearings(10) Seals

Planetary final drives are used on all axles.

Ring gear (2) is mounted on hub (7). The hub issplined onto spindle (4). Spindle (4) is bolted to theaxle housing. Ring gear (2) is held stationary.

Gears (8) are mounted upon planetary carrier (3)which is bolted to wheel (1). Sun gear (6) is splinedto axle shaft (5).

Drive comes to sun gear (6) through axle shaft (5).Ring gear (2) is held stationary, so the planetarycarrier is driven in the same direction as the sungear at a reduced speed. The carrier is bolted tothe wheel and the wheel rotates on bearings (9).

The final drive is lubricated by oil from the axle.Seals (10) allow the oil to be sealed in the finaldrive and the axle.

19Power Train


i01528758

Power Train Hydraulic SystemSMCS Code: 3000; 3100; 4000

The hydraulic system for the power train consists oftwo separate subsystems.

The first system supplies oil to the torque converterand the planetary transmission.

The second system supplies oil to the outputtransfer gear, the interaxle differential lock and thethree axle differential locks.

Torque Converter and Transmission


The transmission hydraulic control system providespressurized oil to the clutches of the transmissionplanetary. , Pressurized oil is also supplied to thetorque converter and to the torque converter lockupclutch.

Oil from the sump (1) of the torque converter isdrawn through suction screen (2) by oil pump (3).

Oil from the pump is supplied through oil filter (4)to downshift solenoid (5) and upshift solenoid (6).Oil is also supplied to selector and pressure controlvalve (13). Downshift solenoid (5) and upshiftsolenoid (6) control the flow of pressurized oil torotary actuator (7). Rotary actuator (7) determinesthe position of selector spool (12) in selector andpressure control valve (13).


Selector spool (12) in selector and pressure controlvalve (13) allows pilot oil to flow to individual valves(8) on pressure control valve (9). The position of theselector spool determines the path of the pilot oilto the individual valves.

Each individual valve is a modulating valve whichcontrols the pressure of the oil that is supplied tothe clutches in the transmission planetary.

Oil from the selector and pressure control valve alsosupplies the torque converter. The oil that is usedby the torque converter is then sent through thetransmission oil cooler and back to the transmissionas lubricant.

Transmission Oil Pump and SuctionScreen


(3) Oil pump (transmission)(14) Port (inlet)(15) Idler gear(2) Suction screen(16) Torque converter housing(17) Gear


(3) Oil pump (transmission)(14) Port (inlet)(18) Hose (pump drive group lubrication)(19) Port (outlet)

Oil pump (15) for the transmission oil is located inthe top of torque converter housing (16).

The oil pump is splined to gear (17) which is drivenby the input to the torque converter via idler gear(15).

The oil is drawn by the oil pump from the sump inthe torque converter housing. The oil then passesthrough suction screen (2) to port (14) in the oilpump. The oil is then pumped from port (19) to thesystem. Hose (18) receives oil from the system inorder to lubricate the pump drive group.

21Power Train


Transmission Oil Filter


(20) Transmission oil filter base(21) Filter element(22) Cavity (oil inlet)(23) Spool (bypass valve)(24) Cavity (oil outlet)(25) Spring (bypass valve)


Location of transmission oil filter

The transmission oil filter is located on the right sideof the engine.

The oil enters oil filter base (20) through cavity (22).The oil flows from cavity (22) through filter element(21) into cavity (24) and out of the filter base.

If there is a restriction in the filter element the oilpressure in the filter increases. The increased oilpressure shifts spool (23) to the right against spring(25). When the spool is moved to the right, oil flowsdirectly from cavity (22) to cavity (24). The oil filterelement is now bypassed.

Transmission Oil Cooler


This is a view from below the transmission oil cooler.

The oil cooler for the transmission is located on theright side of the engine below the oil cooler for thebrake system.

Oil from the torque converter is sent to the oil coolerand the oil is cooled by engine coolant. Oil from theoil cooler is then used to lubricate the transmission,the pump drive group and the accessory drivegroup.


Output Transfer Gears andDifferentials


A second hydraulic circuit supplies lubrication forthe output transfer gears. The circuit also controlsthe interaxle differential and the axle differentials.

Oil from the sump of the output transfer gears (30)is drawn by charging and scavenging pump (26)through magnetic screen (32) in order to removeany metallic particles that may be present in theoil. The charging and scavenging pump chargesthe output transfer gears and the differential locks.The charging and scavenging pump for the outputtransfer gears and the differential locks is mountedon the top of the flywheel housing to the left of theengine.

The oil from the charging and scavenging pumpis fed via filter (27) to solenoid and relief valve(28) that is mounted on the output transfer gearcase. The solenoid and relief valve controls thelock for interaxle differential (29) and the locks forthe axle differentials. The solenoid and relief valvealso provides lubrication oil for the output transfergear (30).

Operation of the solenoid and relief valve appliesoil pressure to the lockup clutch in the interaxledifferential in order to engage the interaxledifferential lock. Within the solenoid and relief valve,a second solenoid valve controls the axle differentiallocks (31) in the three axles. The circuit allows theaxle differential locks to be engaged only when theinteraxle differential lock is engaged.

23Power Train


Engagement of the axle differential locks is achievedwhen the solenoid valve allows pressurized oil fromthe solenoid and relief valve to fill the clutcheson the differentials in each axle. When the axledifferential lock is unselected, the oil in the clutchesof the axle differentials is able to drain to the topof the output transfer gear case as additionallubrication.

The oil enters the output transfer gear case at thetop. The oil drains down to the sump of the outputtransfer gear case and the oil provides lubricationto the gears and the bearings.

i01536341

Transmission HydraulicControlSMCS Code: 3167



Control of the torque converter and the planetarytransmission is achieved by a selector and pressurecontrol valve that controls the supply of pressurizedoil to the pressure control valve. The pressurecontrol valve contains individual valves that controlthe oil pressure in each clutch and the oil pressurein the torque converter lockup clutch.

Oil is supplied by pump (1) through oil filter (2). Thepressurized oil is available to downshift solenoid(3), upshift solenoid (4) and torque converter lockupclutch solenoid (9). Pressurized oil is also suppliedto selector and pressure control valve (13).

Selector and pressure control valve (13) regulatesthe oil pressure. The selector and pressure controlvalve sends pressurized oil to pressure control valve(7) for clutch actuation. The selector and pressurecontrol valve also provides the pilot signal to theindividual valves (6) in the pressure control valve.

The selector and pressure control valve alsosupplies oil to the torque converter. The maximumpressure of the oil to the torque converter isregulated by relief valve (11) in the selector andpressure control valve.

Rotary actuator (5) is controlled by downshiftsolenoid (3) and upshift solenoid (4). The rotaryactuator turns selector spool (10) in the selectorand pressure control valve. The selector spooldetermines the path of the pilot oil to the individualvalves.

When the machine is in NEUTRAL, the downshiftsolenoid is selected. This ensures that the rotaryactuator holds the selector spool in the correctposition. The selector and pressure control valveincludes a neutralizer valve. Neutralizer valve (12)prevents pressurized oil from being supplied to theselector spool unless the engine is started with thetransmission control in the NEUTRAL position.

When the operator selects drive, the ECM for thepower train closes downshift solenoid (3) and opensupshift solenoid (4). The upshift solenoid suppliespressurized oil to the rotary actuator. This causesthe rotary actuator to rotate. This turns the selectorspool in the selector and pressure control valve.Pilot oil is directed by the selector spool to theindividual valves for clutch 2 and clutch 6.

Solenoid valve (9) for the torque converter lockupclutch is closed. This allows torque converter driveas the machine accelerates. As the machine speedmatches the engine speed, the ECM for the powertrain sends an electrical signal to the solenoid valvefor the torque converter lockup clutch. This allowsa pilot oil supply to the modulating valve (8) forthe torque converter lockup clutch. This causesthe torque converter lockup clutch to engagedirect drive between the engine and the planetarytransmission.

The ECM reads the information from the engineoutput speed sensor and from the transmissionoutput speed sensor. The ECM shifts thetransmission at predetermined speeds.

Table 2

SPEED SELECTION


NEUTRAL 1

REVERSE speed 3 & 7

FIRST speed 2 & 6

SECOND speed 1 & 6

THIRD speed 3 & 6

FOURTH speed 1 & 5

FIFTH speed 3 & 5

SIXTH speed 1 & 4

SEVENTH speed 3 & 4

i01545381

Power Train Electronic ControlSystemSMCS Code: 4800

Control of the power train is achieved byelectronically controlled hydraulic actuation. Controlof the power train is maintained by the electroniccontrol module.

The electronic control module is also responsiblefor controlling the other systems that are used onthe machine.

The ECM receives inputs from different sensors andfrom operator requests. The ECM sends electronicsignals in order to control transmission shifts andother power train components.

The ECM receives the following inputs:

• Engine output speed

25Power Train


• Transmission output speed

• Selected gear

• Position of the transmission control lever

• Position of the selector spool

• Position of the hoist lever

• Differential lock switch

• Position of the engine compression brake control

• Transmission hold

• Key start switch

• High gear limit

• Status of the parking brake

• Status of the service brakes

• System faults

The following functions are carried out by the ECM:

• Automatic transmission shifts

• Direct drive (torque converter lockup)

• Transmission hold

• Overspeed control

• Directional shift management

• Protection against abusive shifts

The ECM also carries out other functions whichinclude control of the secondary steering systemand control of the hoist system.

The ECM will also control default mode operation inthe event of electrical failure.

A service technician can use Caterpillar ET tocommunicate with the ECM. The service techniciancan interrogate the ECM for details of faults and theservice technician can monitor operating conditions.


Power Train Electronic ControlSystem


Block diagram of the power train electronic control system

(1) Service tool connector(2) CAT Data Link(3) Caterpillar Monitoring System(4) Caterpillar Monitoring System service

connector(5) Electronic control module (ECM)

(6) Torque converter lockup clutch solenoid(7) Downshift solenoid(8) Upshift solenoid(9) Transmission gear sensor(10) Transmission control(11) Engine

(12) Engine speed sensor(13) Torque converter(14) Transmission(15) Transmission output speed sensors

(two)

Seven hydraulically activated clutches intransmission (14) provide seven forward speedsand one reverse speed. Speed selections anddirection selections are made manually by usingtransmission control (10).

The power train electronic control systemelectronically controls the shifting of thetransmission. In order for the transmission to beshifted to the desired speed and the desireddirection, the ECM (5) receives the operator inputfrom transmission control (10). The ECM sends asignal to downshift solenoid (7) or upshift solenoid(8). The downshift solenoid and the upshift solenoidturn the rotary actuator which turns the selectorspool in the selector and pressure control valve.The modulating valves in the pressure control valvemodulate the oil pressure of the clutches that areselected.

A modulating valve is also used to control oilpressure to the torque converter lockup clutch. Pilotoil is supplied to the modulating valve for the torqueconverter lockup clutch by torque converter lockupclutch solenoid (6). The torque converter lockupclutch provides direct drive between the engine andthe transmission planetary.

The power train ECM uses input signals fromthe following components to ensure correctengagement of the clutches: engine speed sensor(12) and transmission output speed sensors (15).

The power train ECM also controls the followingfunctions: interaxle differential lock, axle differentiallocks, hoist control, and secondary steering system.

27Power Train


Electronic Control Module

The electronic control module (ECM) is located atthe right rear side of the cab. The ECM controlsthe shifting of the transmission. The transmissioncontrol sends the operator input to the ECM. Theoperator input indicates the desired speed forthe transmission and the desired direction for thetransmission. The ECM makes decisions that arebased on the input information and on the memoryinformation. After the ECM receives the inputinformation and the memory information, the ECMsends a corresponding response to the outputs.The inputs and the outputs are connected to themachine harness by two 40-pin connectors.

Inputs

The machine has several input devices. Inputdevices inform the ECM of the operating conditionsof the machine. The machine has two types ofinputs, switch inputs and sensor inputs. The switchinputs of the ECM are provided with the followingsignals from the switches: an open, a ground, anda +battery. Sensors provide a constantly changingsignal to the ECM.

Outputs

The ECM responds to decisions by sendingelectrical signals through the outputs. The outputscan create an action or the outputs can provideinformation to the ECM.

Input/Output

The CAT Data Link is used to communicate with theother electronic control modules on the machine.The CAT Data Link is bidirectional. The CAT DataLink allows the sharing of information with otherelectronic controls.

• The ECM receives the harness code input fromthe Caterpillar Monitoring System.

• The ECM sends the following information to theCaterpillar Monitoring System: engine speed,machine ground speed, parking brake switchstatus, transmission speed selection, and servicecode of the transmission.

• The monitoring system displays this informationfor the operator or for service personnel.

• The ECM communicates with the engine ECM inorder to allow controlled throttle shifting.

Sensors In The Power Train

Sensors provide information to the power trainelectronic control module (ECM) about changingconditions. The sensor signal changes proportionallyto the changing conditions. The following type ofsensor signals are recognized by the power trainECM.

• Frequency signals: The frequency (Hz) of thesensor signal varies as the condition changes.

Transmission Gear Sensor


Transmission Gear Sensor

The transmission gear sensor is an input to thePower Train ECM. The sensor tells the ECM theposition of the rotary actuator and the selectorspool. The sensor is connected mechanically to therotary actuator of the transmission.


Speed Sensors (Engine Output andTransmission Output)


Typical Speed Sensor

There are two transmission output speed sensorsand one engine output speed sensor on themachine. The speed sensors are inputs of theECM. These speed sensors are frequency sensors.Frequency sensors produce a signal (Hz) whichvaries as the condition changes. The sensorgenerates a sine wave signal from the gear teethas the gear teeth pass the sensor. The sensorproduces a signal that equals one pulse per geartooth. This signal is sent to the ECM. The ECMmeasures the frequency of the signal in order todetermine the speed of the condition. The ECMreceives signals from the speed sensors. The ECMuses the input from the speed sensors in orderto determine the speed of the system. The ECMuses the input from the speed sensors in order toregulate transmission shifts. Each speed sensor hastwo connections to the ECM (+ and −).

For all of the speed sensors, connector contact2 is the signal line and connector contact 1 isthe return line. Two transmission speed sensorsmeasure transmission output speed in order toprovide protection against failure.

Note: The speed sensors are used to diagnoseeach other during normal operation. The ECMperiodically checks the value from the speedsensor. If an incorrect value is found, the ECM willlog a service code that indicates a fault for a speedsensor circuit.

i01562748

Output Transfer GearsLubrication SystemSMCS Code: 1300; 3159

The lubrication of the output transfer gears isachieved by a separate hydraulic system fromthe hydraulic system that serves the planetarytransmission and the torque converter . Thelubrication system for the output transfer gears alsoprovides oil for the axle differential locks and for theinteraxle differential lock that is located in the casefor the output transfer gears.

Charging and Scavenging Pumpfor the Output Transfer Gears andDifferential Locks


Charging and scavenging pump for the output transfer gears anddifferential locks

Charging and scavenging pump (1) supplies oilfor the lubrication of the output transfer gears. Thecharging and scavenging pump also supplies oil forthe control of the interaxle differential lock and theaxle differential locks. The charging and scavengingpump is driven from the engine flywheel via an idlergear.

29Power Train


Oil Filter for the Output TransferGears


Oil filter for the output transfer gears

Oil is supplied to oil filter (2) from the gear pump.The oil filter is located behind the cab on the left ofthe machine. The base of the oil filter contains abypass valve in order to allow the oil to continue tothe output transfer gears in the event of a blockagein the oil filter. A switch notifies the operator in theevent of a blockage in the oil filter.

Solenoid and Relief Valve


Solenoid and relief valve

Oil from the oil filter is then fed to solenoid and reliefvalve (3) that is mounted on the case of the outputtransfer gears.

The solenoid and relief valve provides oil to theoutput transfer gears and the differential locks.

The solenoid and relief valve incorporates twosolenoid valves, a priority valve and a relief valve.

One solenoid in the solenoid and relief valvecontrols the oil to the interaxle differential lock andthe oil to the solenoid valve for the axle differentiallocks.

A second solenoid controls the oil to the axledifferential locks.

The priority valve gives priority to the oil supplyfor the differential locks over the oil supply to theoutput transfer gears.

The relief valve regulates the maximum pressure inthe output transfer gears and the differential locksystem.

Oil from the solenoid and relief valve enters thecase for the output transfer gears at the top. The oilis gravity fed to the output transfer gears.

Magnetic Screen for the OutputTransfer Gears


Magnetic screen for the output transfer gears

Oil is scavenged from the case of the output transfergears through magnetic screen (4). The magneticscreen collects any ferrous debris that may bepresent in the oil for the output transfer gears.


i01540730

Pressure Control Valve(Transmission)SMCS Code: 3074

Transmission Pressure ControlValve


31Power Train


Pressure control valve (1) has seven modulationreduction valves (2) for the transmission planetaryand one modulation reduction valve (3) for thetorque converter lockup clutch. There is onemodulation reduction valve for each clutch in thetransmission planetary. Each modulation reductionvalve acts separately. This is known as IndividualClutch Modulation (ICM). The modulation reductionvalves control the amount of pressure that will beused for clutch engagement and for the release ofthe clutch. The modulation reduction valves alsodetermine the duration of clutch engagement.

Each load piston body (4) has an identification letterfor the purposes of disassembly and assembly.Pilot passages (5) are connected to passagesfrom the rotary selector spool of the selector andpressure control valve. Pump oil from the selectorand pressure control valve is in passage (6). Drainpassages (7) are connected to the transmissioncase reservoir.

All of the modulation reduction valves operate in asimilar way, so only the basic operation is provided.

The Beginning of a Shift and the Clutchis Filling



When a shift is started, pilot passage (5) receivespilot oil at the correct sequence from the rotaryselector spool. Selector piston (8) and loadpiston (9) move against the force of springs (10).Modulation reduction valve (11) moves againstthe force of spring (12). Passage (13) is blockedto drain passage (14). Passage (13) is open topassage (6). The pump oil now begins to fill theclutch. The pressure of the oil that is filling the clutchis balanced against the force of springs (10) as thesprings are compressed by the selector piston. Thisis the primary pressure for the clutch. The primarypressure helps to fill the clutch smoothly in order toavoid harsh transmission shifts.

As the oil flows to passage (13), oil is able to flowthrough load piston orifice (15) and passage (16).

Completed Shift with an Engaged Clutch


33Power Train


After the clutch is full of oil, the pressure of thepump oil in the selected clutch increases. Thepressure of the oil that is flowing through the loadpiston orifice increases. This oil goes betweenselector piston (8) and load piston (9). The oilmoves the load piston against springs (10). Thisfurther increases the compression of the springs.As the springs are compressed, the force of thesprings is increased. The pressure of the oil in theclutch is balanced against the force of springs (10).This allows an increase in the oil pressure in theclutch. Clutch oil flows through an orifice in themodulation reduction valve (11). Ball check valve(17) opens and oil flows into the slug chamber atthe left end of the modulation reduction valve.

The pressure in the clutch is now at the maximum.Modulation reduction valve (11) moves to the rightand to the left in order to maintain a constantpressure in passage (13).

The amount of time that is necessary for themaximum pressure in the clutch to be reached isdependent on the size of load piston orifice (15) andthe force of springs (10). The force of springs (10)can be adjusted by using shims in load piston (9).


Shift with a Released Clutch


When a clutch is disengaged, pilot passage (5) isopen in order to drain through the rotary selectorspool. The force of springs (10) moves selectorpiston (8) fully to the right against load pistonbody (18). Passage (16) is now aligned with drainpassage (19). The force of springs (10) moves loadpiston (9) fully to the right against selector piston (8).

Modulation reduction valve (11) is moved fully tothe right by the force of spring (12). In this position,pump oil in passage (6) cannot flow into passage(13). Passage (6) is open to drain passage (14) andthe pressure in the clutch is released. Decay orifice(20) in drain passage (19) controls the amount oftime that is necessary for the clutch pressure torelease.

35Power Train


Torque Converter Lockup Clutch


The operation of the modulating valve for the torqueconverter lockup clutch is identical to the operationof the modulating valves for the clutches in thetransmission planetary. Pilot oil is supplied by thetransmission oil pump. The pilot oil is controlled bythe torque converter lockup solenoid.

The torque converter lockup solenoid is locatedalongside the downshift solenoid and the upshiftsolenoid.

The modulating valve for the torque converterlockup clutch is mounted on the transmissionpressure control valve.

The Power Train Electronic Control Module (PowerTrain ECM) will energize the torque converter lockupclutch solenoid when direct drive is necessary.During direct drive, the engine is mechanicallyconnected to the transmission by the activation ofthe lockup clutch.

When direct drive is not necessary, the torqueconverter lockup clutch solenoid is deactivated. Thepilot oil supply to the modulating valve for the torqueconverter lockup clutch is cut off. The machine willthen be in torque converter drive. The engine willbe hydraulically connected to the transmission.

Engaging the Lockup Clutch

When the Power Train ECM activates the lockupclutch solenoid, pilot oil from the transmission pumpis allowed to flow into pilot oil passage (21).

As pilot oil flows into the pilot oil passage, selectorpiston (22) and load piston (23) are moved to theright against the force of spring (24). Drain passage(25) is blocked. Spring (24) pushes modulationreduction valve (26) against the force of spring(27). As modulation reduction valve (26) movesto the right, drain passage (28) is blocked, andpressurized oil is allowed to flow from passage (6) topassage (29) to the torque converter lockup clutch.

Oil in passage (29) also flows through load pistonorifice (30). This oil goes between selector piston(22) and load piston (23). This moves load piston(23) further to the right.


The pressure of the clutch oil in passage (29)increases after the clutch is full of oil. Some of theoil from passage (29) goes through orifice (31) inmodulation reduction valve (26). This oil opensball check valve (32). The oil then goes into slugchamber (33). This pressure helps the springs pushboth modulation reduction valve (26) and loadpiston (23) back to the left. The oil that is flowingthrough load piston orifice (30) is delivered at a fixedrate. While load piston (3) is controlled by the oilfrom load piston orifice (30), modulation reductionvalve (26) moves up and down. This causes thepressure in the lockup clutch to increase gradually.This gradual increase due to the movement ofthe spool is called modulation. The modulationof modulation reduction valve (26) maintains aconstant pressure in passage (29). When loadpiston (23) goes fully against the stop, modulationstops. The pressure in the lockup clutch is now atthe maximum. The lockup clutch is fully engaged.

The amount of time that is necessary for themaximum pressure in the lockup clutch to bereached is dependent on the size of load pistonorifice (30) and the force of spring (24). The forceof spring (24) can be adjusted by using shims inload piston (23).

Releasing the Lockup Clutch

When pilot oil passage (21) does not receive pilotoil, the force of spring (24) moves selector piston(22) to the left against load piston body (34). Thisuncovers drain passage (25). Oil between selectorpiston (22) and load piston (23) drains throughdrain passage (25).

Passage (35) is now aligned with drain passage(25). The force of spring (24) moves load piston(23) fully against selector piston (22). Modulationreduction valve (26) moves up to the fullest extentas a result of the force of spring (24). In this position,pump oil in passage (6) cannot go into passage(29). Passage (29) is now open to drain passage(28). The pressure in the lockup clutch is released.

Note: Drain passages (25), (28), (19), (14), and (27)are connected. The return oil goes into the torqueconverter sump.

37Power Train


i01540704

Selector and Pressure ControlValve (Transmission)SMCS Code: 3157; 5117


The selector and pressure control valve controls theflow of oil that goes to the pressure control valve.The selector and pressure control valve consists offive valves. The following chart provides the basicfunction of each valve.


Table 3

Operation Of The Components In The SelectorAnd Pressure Control Valve

Valve Function

Priorityreduction valve

(2)

This valve controls the pressureof the pilot oil that is available to

rotary selector spool (4).

Neutralizervalve (3)

When the transmission is not inNEUTRAL and the engine is started,this valve stops the flow of pilot oil

to rotary selector spool (4).

Rotary selectorspool (4)

The rotary selector spool sendspilot oil to the appropriate

transmission clutches.

Relief valve(12)

This valve controls the maximumpressure in the transmission

hydraulic system.

Torqueconverter inletrelief valve (11)

This valve controls the maximum inletoil pressure to the torque converter.

Priority Reduction Valve

At the selector and pressure control valve, the oilfrom the transmission oil pump flows to severallocations. The oil flows through passage (1) topriority reduction valve (2). The oil flows through anorifice in the priority reduction valve. This oil opensa check valve. The oil then flows to the upper endof priority reduction valve (2).

As the oil pressure increases, the priority reductionvalve is moved downward against the force of thespring. The pressure of the oil that is flowing frompriority reduction valve (2) to neutralizer valve (3) iscontrolled by the priority reduction valve.

As priority reduction valve (2) moves downward,pump oil in passage (1) is able to flow throughthrough passage (13). Some of this oil flows to reliefvalve (12). Relief valve (12) controls the maximumpressure in passages (1), (13), and (8). Some ofthe oil from passage (13) flows through passage(8) to the pressure control valve. This oil is usedto fill the clutches in the transmission. Some of theoil from passage (13) also flows to rotary selectorspool (4). This oil activates neutralizer valve (3).When the rotary selector spool is in the NEUTRALposition, oil is able to flow to chamber (14). Thiscauses neutralizer valve (3) to move downward.When neutralizer valve (3) is moved downward, theoil flows into chamber (5) of rotary selector spool(4). Chamber (5) has a screen that filters the oil.This oil is able to flow to the pressure control valve.This pressure oil is the pilot oil that controls themovement of the selector pistons in the pressurecontrol valve.

Neutralizer Valve

Neutralizer valve (3) will not allow movement of themachine if the engine is started and rotary selectorspool (4) is not in the NEUTRAL position.

When the engine is started and the transmission isin NEUTRAL, pressure oil from passage (13) flowsto rotary selector spool (4). The pressure oil thenflows to chamber (14). The pressure in chamber(14) moves neutralizer valve (3) downward againstthe force of the spring. This allows pilot oil to goaround the neutralizer valve to chamber (5) of therotary selector spool. The clutches can be engagedin the transmission.

As neutralizer valve (3) moves downward, pilot oilis able to flow through an orifice in the neutralizervalve to the upper end of the neutralizer valve.Neutralizer valve (3) is now held in the open positionby the pressure of the pilot oil.

When rotary selector spool (4) is moved from theNEUTRAL position, pressure oil from passage (13)cannot go to chamber (14). Chamber (14) is nowopen to chamber (6) because of the position ofrotary selector spool (4).

When the machine is not in NEUTRAL and theengine is started, the position of rotary selectorspool (4) stops the flow of pump oil to chamber(14). Neutralizer valve (3) will not move downward inorder to provide oil to chamber (5). No oil can flowto the selector pistons of the pressure control valve.The clutches in the transmission will not engage.

Rotary Selector Spool

Rotary selector spool (4) determines the selectorpistons in the pressure control valve that receivepilot oil and the selector pistons that are drained.Orifices in the spool provide the correct sequence inorder for the clutches to engage. A rotary actuatoris mechanically connected to the upper end ofthe rotary selector spool. The rotary actuator ishydraulically controlled by the upshift solenoid andthe downshift solenoid. The rotary actuator turnsrotary selector spool (4). The transmission gearswitch is also connected to the upper end of thespool. The transmission gear switch communicateswith the Power Train Electronic Control Module.Cam (7) is fastened to the lower end of the spool.Springs (9) are in contact with cam (7). The springsprovide detent positions in order to hold the spoolin each selected speed position.

39Power Train


Chamber (5) of rotary selector spool (4) containspilot oil. The position of the spool will send this pilotoil through a passage to the pressure control valve.The oil flows to a selector piston. This causes theselector piston to move. This will cause a clutchto engage in the transmission. Chamber (5) has ascreen which stops foreign material from enteringthe pressure control valve.

The clutches of the transmission that aredisengaged return any pressure oil that is in theselector pistons to chamber (6). Chamber (6) allowsthe oil to go to the transmission case reservoir.

In the NEUTRAL position, rotary selector spool (4)sends pump oil to chamber (14) in order to moveneutralizer valve (3). In the other speed positions,chamber (14) is blocked from pump oil and opento chamber (6).

Relief Valve

Relief valve (12) controls the maximum pressure inthe transmission hydraulic system. Pump oil comesfrom passage (13) to relief valve (12). The oil flowsthrough an orifice in the relief valve. This opens apoppet valve. Oil fills the chamber between thepoppet and the slug. As the pressure increases, theoil moves relief valve (12) upward against the forceof the spring. When the pressure of the oil reachesthe relief pressure, relief valve (12) allows oil to flowthrough passage (10) to the torque converter.

The pressure setting of relief valve (12) can bechanged by the removal or the addition of shimsinside the spool of the relief valve.

Torque Converter Inlet Relief Valve

Torque converter inlet relief valve (11) controls themaximum oil pressure that is going into the torqueconverter. Oil that flows past relief valve (12) willthen flow to the torque converter. If the pressure ofthe oil reaches the relief pressure, torque converterinlet relief valve (11) will open. The oil will flow tothe transmission case reservoir until the pressure isreduced to less than the maximum pressure that isrequired for the torque converter.


i01541642

Rotary Actuator(Transmission)SMCS Code: 3166


The rotary actuator is controlled by downshiftsolenoid (1) and upshift solenoid (2). Pressure oilfrom either solenoid flows into chamber (3). Thepressure oil presses against stationary vane (12)and against rotary vane (14) of rotor (15). Thispressure oil causes the rotor to turn. Rotor (15) ismechanically connected to the rotary selector spool.The rotary selector spool is part of the selector andpressure control valve. Rotor (15) turns the rotaryselector spool.

During an upshift, pressure oil from the upshiftsolenoid flows through passage (9). This causesupshift valve (10) to move to the left. Drain passage(11) is now closed by the upshift valve. The pressureoil flows into upshift valve (10). This moves ball (8)to the left and oil flows into chamber (13) betweenstationary vane (12) and rotary vane (14). Thiscauses rotor (15) to turn in a clockwise direction.

The oil that is in chamber (3) on the opposite sideof rotary vane (14) presses against downshift valve(4). This causes ball (7) to move to the right side.Oil is then blocked from flowing through passage(6). As the rotor turns, the oil in chamber (3) pushesdownshift valve (4) to the right until the valve opensdrain passage (5). The oil that is in chamber (3) isnow able to drain.

When the rotary selector spool and rotor (15)achieve the correct speed position, the transmissiongear switch that is connected to the rotary selectorspool sends an electrical signal to the Power TrainElectronic Control Module (Power Train ECM). ThePower Train ECM closes the upshift solenoid. Thisstops the flow of pressure oil in passage (9). Themovement of rotor (15) then stops.

During a downshift, pressure oil from the downshiftsolenoid flows through passage (6). Downshift valve(4) is moved to the left. This closes drain passage(5). The pressure oil from passage (6) goes intodownshift valve (4). The pressure oil moves ball (7)to the left and oil flows into chamber (3). This causesrotor (15) to turn in a counterclockwise direction.

41Power Train


The oil that is in chamber (13) presses againstupshift valve (10). This causes ball (8) to move tothe right. This stops oil from going through passage(9). As the rotor turns, the oil in chamber (13)pushes the upshift valve to the right until drainpassage (11) is open to chamber (13).

When the rotor achieves the correct speed position,the Power Train ECM deactivates the downshiftsolenoid. Pressure oil in passage (6) is stopped.This stops the movement of rotor (15).

When the transmission is in the NEUTRAL position,rotor (15) is in the position that is shown. Thedownshift solenoid is always activated in theNEUTRAL position so that the rotor is locked inposition.

42Power TrainTesting and Adjusting Section

Testing and AdjustingSection

Troubleshooting

i01526102

Machine Preparation forTroubleshootingSMCS Code: 3000-035

When testing and adjusting the transmission andpower train, move the machine to an area clear ofobstructions, with safe exhaust ventilation for theexhausts. Sudden movement of the machine or re-lease of oil under pressure can cause injury to per-sons on or near the machine. To prevent possibleinjury, do the procedure that follows before testingand adjusting the transmission and power train.

1. Move the machine to a smooth horizontallocation. Move away from any machines that areworking and any personnel.


Dump body prop

2. Raise the dump body of the truck. Install thedump body prop in order to support the dumpbody.

3. Ensure that the transmission control is in theNEUTRAL position. Move the parking brakecontrol to the ENGAGED position and stop theengine.

4. Permit only one operator on the machine. Eitherkeep other personnel away from the machine, orkeep other personnel in the sight of the operator.

5. Install the steering frame lock. Refer to Operationand Maintenance Manual, SEBU7498.

6. Place blocks in front of the wheels and behindthe wheels.

7. Make sure that all oil pressure is released beforeany fittings, hoses or components are worked on.

8. Push on the brake pedal many times until thereis no brake oil pressure.

Visual checks are the first steps in order totroubleshoot a problem. The visual checks find theproblems that can be quickly corrected. If the visualchecks do not show any problems, the operationalchecks are the next steps. The operational checkspermit the identification of possible problems withthe machine during operation.

i01556822

General TroubleshootingInformationSMCS Code: 3000-035

When you are attempting to define a problem withthe power train, it is necessary to perform theprocedures that are contained in this section.

A visual inspection of the system must be carriedout in order to eliminate many of the less complexproblems.

Upon completion of a visual inspection, if the causeof the problem has not been diagnosed, carry outoperational checks of the system.

If both visual inspection and operational checkshave been carried out and there is still no clearindication of the cause of the problem then it will benecessary to refer to the troubleshooting proceduresand the test procedures that are contained in thismanual.

Troubleshooting a system such as the powertrain is a complex operation. Refer to the varioustroubleshooting sections in this manual for specificroutines for troubleshooting.

43Power Train


This list of possible problems and possiblecorrections will only provide an indication of thelocation of a problem and the repairs that arerequired. It is important to remember that a problemis not necessarily caused by a single part, but bythe relation of one part to a number of other parts.This information cannot provide all the possibleproblems and corrections. It is necessary for servicepersonnel to define the problem. Any repairs maythen be carried out.

i01526104

Visual InspectionSMCS Code: 3000-035

Perform a visual inspection at the beginningof troubleshooting a problem. Ensure that thetransmission control is in the NEUTRAL position.Move the parking brake control to the ENGAGEDposition and stop the engine.

Do not check for leaks with your hands. Pin hole(very small) leaks can result in a high velocity oilstream that will be invisible close to the hose. Thisoil can penetrate the skin and cause personal in-jury. Use cardboard or paper to locate pin holeleaks.

1. Check the oil levels for the various componentsof the power train.

Check the oil level for the torque converterand the transmission. Refer to Operation andMaintenance Manual, SEBU7498, “TorqueConverter and Transmission Oil Level - Check”.

Check the oil level for the transfer gear. Refer toOperation and Maintenance Manual, SEBU7498,“Transfer Gear Oil Level - Check”.

Check the oil levels for the differentials and finaldrives. Refer to Operation and MaintenanceManual, SEBU7498, “Differential and Final DriveOil Level - Check”.

2. Check the level of the coolant in the enginecooling system. Refer to Operation andMaintenance Manual, SEBU7498, “CoolingSystem Level - Check”.

Note: Engine coolant passes through the oil coolerfor the transmission in order to cool the torqueconverter and the transmission oil.

3. Check for leaks.

Inspect all oil lines, hoses, and connections fordamage or for leaks. Look for oil on the groundunder the machine.

Note: If oil can leak out of a fitting or a connection,air can leak into the system. Air in the system canbe as bad as a low oil level.

4. Check the electrical system.

Inspect the harnesses and the electricalconnectors for the ECM. Refer to ElectricalSchematic, RENR5136.

With the engine start switch and the batterydisconnect switch in the OFF position, checkthe 20 ampere fuse for the Electronic ControlModule. If the fuse is open, replace the fuse.Refer to Operation and Maintenance Manual,SEBU7498, “Fuses - Replace”.

Inspect the electrical harnesses for damagedwires or for broken wires. Disconnect eachconnector and look for pins and sockets thathave been bent, broken, or removed. Look forany foreign material inside the connectors. Theconnectors must be tightened with normal force.The connectors must be disconnected with thesame amount of force.

Check the Electronic Control Module. Refer toSystems Operation, Troubleshooting, Testing andAdjusting, RENR3442, “Power Train ElectronicControl System”.

5. Check the batteries.

Turn the battery disconnect switch to the ONposition and check the condition of the batteries.

6. Check the filters and the screens.

Inspect the suction screen for the torqueconverter and the transmission. Clean thesuction screen for the torque converter andthe transmission. Refer to Operation andMaintenance Manual, SEBU7498, “TorqueConverter Scavenge Screen - Clean”.

Inspect the oil filter for the torque converterand the transmission. Refer to Operation andMaintenance Manual, SEBU7498, “TorqueConverter and Transmission Oil Filter - Replace”in order to remove the oil filter. Refer to Operationand Maintenance Manual, SEBU7498, “Oil Filter- Inspect” in order to inspect the oil filter.


Note: The oil filter for the torque converter andthe transmission has a bypass valve which allowsoil to bypass the oil filter elements when the inletpressure to the oil filter rises due to a blockagein the oil filter. Any oil that does not go throughthe filter elements goes directly into the hydrauliccircuit. Dirty oil causes restrictions in valve orifices,sticking valves, etc.

Inspect the oil filter for the transfer gear. Refer toOperation and Maintenance Manual, SEBU7498,“Transfer Gear Oil Filter - Replace” in order toremove the oil filter. Refer to Operation andMaintenance Manual, SEBU7498, “Oil Filter -Inspect” in order to inspect the oil filter.

Note: The oil filter for the transfer gear has abypass valve which allows oil to bypass the oil filterelements when the inlet pressure to the oil filterrises due to a blockage in the oil filter. Any oil thatdoes not go through the filter elements goes directlyinto the hydraulic circuit. Dirty oil causes restrictionsin valve orifices, sticking valves, etc. The oil filterfor the transfer gear incorporates a switch, whichilluminates an indicator in the cab. This indicatoralerts the operator of a restriction in the oil filter forthe transfer gear.

Inspect the magnetic screen for the torqueconverter and the transmission. Refer toOperation and Maintenance Manual, SEBU7498,“Torque Converter Scavange Screen - Clean”.The magnetic screen for the torque converterand the transmission is located within thesuction screen for the torque converter and thetransmission.

Inspect the magnetic screen for the transfer gear.Refer to Operation and Maintenance Manual,SEBU7498, “Transfer Gear Magnetic Screen -Clean”.

Magnets separate the ferrous particles from thenonferrous particles.

This is a list of some of the particles that may befound in the filter elements:

• Aluminum particles give the indication oftorque converter failure or sleeve bearingfailure.

• Bronze particles give the indication of sleevebearing failure.

• Rubber particles give the indication of rubberseal or hose failure.

• Shiny steel particles give the indication ofpump failure.

• Iron chips, steel chips or plastic particlesgive the indication of broken components intransmission or transfer gears.

If any contamination is found in the filter elementsor the screens, all the components of thetransmission hydraulic system must be cleaned.Do not use any damaged parts. Any damagedparts must be removed and new Caterpillar partsmust be installed.

i01556743

Operational ChecksSMCS Code: 3000-035

Operate the machine in each direction and inall speeds. Operate the interaxle differential andoperate the axle differentials. Check that the powertrain is operating correctly in all functions. If thepower train is not operating correctly refer to thetroubleshooting information that is contained inthis manual. Use the troubleshooting information inorder to investigate the problem.

The checks for troubleshooting that are includedin this manual are designed to guide servicepersonnel in a correct troubleshooting procedure.The checks and procedures are set in sequence inorder to find problems and causes quickly.

The checks for troubleshooting should be carriedout in order. Do not proceed to the next check untilthe current check has been carried out fully. If thecorrect result for the check is found, go directly tothe next check.

Take note of all warnings and notices in thesechecks. You must read all the warnings and thenotices before you start a check. Before carrying outa procedure, it is important to read the procedurethoroughly.

The checks that follow can be used to find many ofthe problems that may occur during the operationof the machine. The checks that follow can alsogive an indication of the part of the system that hasthe problem.

45Power Train


i01545887

Torque ConverterTroubleshootingSMCS Code: 3101-035

Note: The troubleshooting information is intended toaid in diagnosing a given problem. The possiblecauses are ordered from the most probable causeto the least probable cause. The possible causesshould be examined in order until the problem isresolved.

Refer to Systems Operation, Testing and Adjusting,“Machine Preparation for Troubleshooting”before you perform any testing and adjusting ortroubleshooting.

Prior to carrying out troubleshooting on the torqueconverter, use Caterpillar ET in order to diagnoseany fault codes that may be present. Refer toSystems Operation, Troubleshooting,Testing andAdjusting , RENR3442, “Power Train ElectronicControl System”.

If fault codes are present, repair the cause of thefault code.

The Torque Converter or theTransmission is Overheating

Possible Cause

1. The machine may have been operatedincorrectly.

• Operate the machine in the correct manner.Refer to Operation and Maintenance Manual,SEBU7498.

2. The level of the engine coolant is lower than thespecification.

• Check the engine coolant level. Refer toSystems Operation, Testing and Adjusting,“Visual Inspection”.

3. The power train oil level is lower than thespecification.

• Check the power train oil level. Refer toSystems Operation, Testing and Adjusting,“Visual Inspection”.

4. The engine cooling system and the fan drivesystem may not be functioning correctly.

• Refer to Systems Operation, Testing andAdjusting, RENR5126, “Hoist, Steering,Suspension, and Fan Drive Systems” for furtherinformation regarding the fan drive system.

• Refer to Systems Operation, Testing andAdjusting, RENR1362 for more information onthe engines for the 740.

5. There is debris and damaged components inthe power train.

• Inspect the oil filter for debris.

• Determine the origin of the debris and repairthe damaged component.

• Change the oil in the power train and install anew oil filter.

6. The coolant flow through the transmission oilcooler is below the specification.

7. The oil flow through the transmission oil cooler isbelow the specification.

• Check the oil pressure to the transmission oilcooler. Refer to Systems Operation, Testingand Adjusting, “Power Train Pressures”.

8. The inlet relief pressure for the torque convertermay not be within the specification.

• Check the inlet relief pressure for the torqueconverter. Refer to Systems Operation, Testingand Adjusting, “Power Train Pressures”.

• Adjust the torque converter inlet relief valve.Refer to Systems Operation, Testing andAdjusting, “Transmission Hydraulic Control -Test and Adjust”.

9. The torque converter is worn or damaged.

• Inspect the components of the torque converterfor wear or damage. Refer to Disassembly andAssembly, RENR5139, “Torque Converter -Disassemble and Assemble”.

10. The torque converter lockup clutch is notfunctioning correctly.

• Test the function of the torque converter lockupclutch. Refer to Systems Operation, Testingand Adjusting, “Power Train Pressures”.

The Torque Converter LockupClutch Does Not Engage

Possible Cause

1. There may be an electrical fault between theECM for the power train and the solenoid for thetorque converter lockup clutch.


• Check the wiring and check the connectors fordamage. Refer to Systems Operation, Testingand Adjusting, “Visual Inspection”.

• Repair any damage that is found in the wiringharness or replace any loose connections thatare found.

2. The power train oil level is below the specification.



• Inspect the oil filter for debris.



4. The pressure of the oil in the transmissionhydraulic control system may not be within thespecification.

• Test the pressures of the oil in the transmissionhydraulic control system. Make anynecessary repairs or adjustments. Refer toSystems Operation, Testing and Adjusting,“Transmission Hydraulic Control - Test andAdjust”.

5. The solenoid for the torque converter lockupclutch does not function correctly.

• Check the operation of the solenoid for thetorque converter lockup clutch before theengine start switch is turned off. Refer toSystems Operation, Testing and Adjusting,“Transmission Hydraulic Control - Test andAdjust”.

6. The modulating valve for the torque converterlockup clutch may not be functioning correctly.

• Check the operation of the modulatingvalve for the torque converter lockup clutch.Systems Operation, Testing and Adjusting,“Transmission Hydraulic Control System - Testand Adjust”.

7. Components in the torque converter lockupclutch may be worn.

• Check the oil pressure in the torque converterlockup clutch. Refer to Systems Operation,Testing and Adjusting, “Power Train Pressures- Test”.

• Check the condition of the piston in the torqueconverter lockup clutch. Refer to Disassemblyand Assembly, RENR5139, “Torque Converter- Disassemble and Assemble”.

The Torque Converter LockupClutch Does Not Disengage and theEngine Dies at Low Speed

Possible Cause

1. There may be an electrical fault between theECM for the power train and the solenoid for thetorque converter lockup clutch.




• Inspect the oil filter for debris. Refer to SystemsOperation, Testing and Adjusting, “VisualInspection”.



3. The solenoid for the torque converter lockupclutch does not function correctly.

• Check the operation of the solenoid for thetorque converter lockup clutch before theengine start switch is turned off. Refer toSystems Operation, Testing and Adjusting,“Transmission Hydraulic Control - Test andAdjust”.

4. The modulating valve for the torque converterlockup clutch may not be functioning correctly.

• Check the operation of the modulatingvalve for the torque converter lockup clutch.Systems Operation, Testing and Adjusting,“Transmission Hydraulic Control System - Testand Adjust”.

47Power Train


5. The piston in the torque converter lockup clutchmay be sticking.

• Check the oil pressure in the torque converterlockup clutch. Refer to Systems Operation,Testing and Adjusting, “Power Train Pressures- Test”.

• Check the condition of the piston in the torqueconverter lockup clutch. Refer to Disassemblyand Assembly, RENR3448, “Torque Converter- Disassemble and Assemble”.

i01554329

Transmission PlanetaryTroubleshootingSMCS Code: 3160-035

Note: The troubleshooting information is given to aidin diagnosing a given problem. The possible causesare ordered from the most probable cause to theleast probable cause. The possible causes shouldbe examined in order until the problem is resolved.


Prior to carrying out troubleshooting on thetransmission planetary group, use CaterpillarET in order to diagnose any fault codes thatmay be present. Refer to Systems Operation,Troubleshooting, Testing and Adjusting, RENR3442,“Power Train Electronic Control System”.

Troubleshooting the Transmission

The Machine Will Not Move

Possible Cause

1. The transmission control may be faulty.

• Test the transmission control for correctoperation and recalibrate the transmissioncontrol. Refer to Systems Operation,Troubleshooting, Testing and Adjusting,RENR3442, “Transmission Control (Shift Lever)- Calibrate”.




• Test the pressures of the oil in the transmissionhydraulic control system. Make any necessaryrepairs or adjustments. Refer to SystemsOperation, Testing and Adjusting, “Power TrainPressures”.

4. One or more individual valves for the transmissionclutches may not be functioning correctly.

• Test the individual valves for the transmissionclutches. Refer to Systems Operation, Testingand Adjusting, “Transmission Hydraulic Control- Test and Adjust”.

5. There may be a blockage in the selector spool.

• Test the pilot pressure for the transmissionhydraulic control system and test the clutchpressures. Refer to Systems Operation, Testingand Adjusting, “Transmission Hydraulic Control- Test and Adjust”. If the clutch pressures arelow and the pilot pressure is normal, removethe selector spool from the selector andpressure control valve and inspect the selectorspool for blockages.

6. The neutralizer valve in the selector and pressurecontrol valve may be preventing the machinefrom engaging a gear.

• The selector spool was not in the NEUTRALposition when the engine was started. Movethe transmission control to the NEUTRALposition and stop the engine. Restart theengine and attempt to engage a forward gear.

• Test the correct function of the neutralizervalve. Refer to Systems Operation, Testing andAdjusting, “Transmission Hydraulic Control -Test and Adjust”.

7. The wiring harness for the power train may bedamaged.



8. The screen inside the selector spool in thetransmission hydraulic control may be blocked.

• Inspect the screen and clean the screen. Referto Systems Operation, Testing and Adjusting,“Visual Inspection”.




• Determine the origin of the debris and repairthe damaged components.


10. There may be a mechanical failure of anothermajor component in the power train.

• Check the power train components fordamage.

The Transmission Stays in One Gear orThe Transmission Will Not Shift Correctly

Possible Cause

1. The wiring harness for the power train may bedamaged. The wiring to the upshift solenoid orthe downshift solenoid may be damaged.



2. The transmission hold switch may be engaged.

• Release the transmission hold switch. Referto Operation and Maintenance Manual,SEBU7498, “Transmission Control”.

3. The high gear limit for the transmission may havebeen selected.

• Check if a high gear limit has been selected.Refer to Operation and Maintenance Manual,SEBU7498, “Changing Speed and Direction”.

4. The transmission control lever may not be in theFLOAT position.

• Move the transmission control lever to theFLOAT position.

5. The transmission oil may be cold.

• Check the temperature of the transmission oil.

• Allow the oil in the transmission to warm upfully.

6. There may be a fault in the transmission ECM.

• Refer to Systems Operation, Troubleshooting,Testing and Adjusting, RENR3442, “PowerTrain Electronic Control System”.



8. The service brakes may not be released fully.

• Check the correct operation of the servicebrakes. Refer to Systems Operation, Testingand Adjusting, RENR5139, “Braking System”.

9. The transmission output speed sensors may befaulty.

• Check the connections on the transmissionoutput speed sensors. Refer to SystemsOperation, Testing and Adjusting, “VisualInspection”.

• Test the transmission output speed sensors.Refer to Systems Operation, Troubleshooting,Testing and Adjusting, RENR3442, “PowerTrain Electronic Control System”.

10. The transmission may be operating in anelevated shift point mode.

• Check the correct function of the ECM and theinputs to the ECM. Refer to Systems Operation,Testing and Adjusting, RENR3442, “PowerTrain Electronic Control System”.



12. One or more of the individual valves for thetransmission clutches may not be functioningcorrectly.

49Power Train


• Test the function of the individual valvesfor the transmission clutches. Refer toSystems Operation, Testing and Adjusting,“Transmission Hydraulic Control - Test andAdjust”.

13. The decay orifice in one of the individual valvesfor the transmission clutches may be blocked.

• Inspect the individual valves and clear anyblockages in the decay orifices.

14. The drain orifice in the end of the selector spoolin the transmission hydraulic control may beblocked.

• Inspect the selector spool and clear anyblockages in the selector spool.





16. The seals on the piston in the transmissionclutch may be leaking.

• Check the pressure of the oil in the clutch underfull engagement. Refer to Systems Operation,Testing and Adjusting, “Transmission HydraulicControl System - Test and Adjust”.

17. There may be damaged components in theclutches for the transmission.

• Inspect the oil for debris. Refer to SystemsOperation, Testing and Adjusting, “VisualInspection”.

• Inspect the clutches for damage. Refer toDisassembly and Assembly, RENR5138,“Transmission Planetary - Disassemble andAssemble”.

• Check that the disks and the plates are withinthe specified dimensions. Refer to Disassemblyand Assembly, RENR5138, “TransmissionPlanetary - Disassemble and Assemble”.

• Check the springs in the clutches. Refer toService Manual, RENR5133, “Power TrainSpecifications” for the correct specificationsfor the springs in the transmission clutches.

18. The torque converter lockup clutch may not beoperating and there may be insufficient groundspeed for a transmission shift.

• Test the operation of the torque converterlockup clutch. Refer to Systems Operation,Testing and Adjusting, “Transmission HydraulicControl - Test and Adjust”.

The Transmission Slips In One Gear

Possible Cause



2. One of the individual valves for the transmissionclutches may not be functioning correctly.

• Test the individual valves. Refer toSystems Operation, Testing and Adjusting,“Transmission Hydraulic Control System - Testand Adjust”.

• A load piston plug may not be installed in theindividual valve for the transmission clutchesthat may be affected. Check that the loadpiston plugs are correctly installed in theindividual valves.

3. The seals on the piston in one of the transmissionclutches may be leaking.

• Check the pressure of the oil in the clutch underfull engagement. Refer to Systems Operation,Testing and Adjusting, “Transmission HydraulicControl - Test and Adjust”.











The Transmission Is Overheating

Possible Cause

1. The power train oil level is outside thespecifications.


2. The machine may have been operatedincorrectly.

• Operate the machine in the correct manner.Refer to Operation and Maintenance Manual,SEBU7498.

3. The level of the engine coolant is lower than thespecification.

• Check the engine coolant level. Refer toSystems Operation, Testing and Adjusting,“Visual Inspection”.

4. The engine cooling system and the fan drivesystem may not be functioning correctly.

• Refer to Systems Operation, Testing andAdjusting, RENR5136, “Hoist, Steering,Suspension, and Fan Drive Systems” for furtherinformation regarding the fan drive system.

• Refer to Systems Operation, Testing andAdjusting, RENR1363.

5. The coolant flow through the transmission oilcooler is below the specification.

6. The oil flow through the transmission oil cooler isbelow the specification.

• Check the oil pressure to the transmission oilcooler. Refer to Systems Operation, Testingand Adjusting, “Power Train Pressures”.

7. The torque converter inlet pressure is outsidespecifications.

• Check the torque converter inlet pressure.Refer to Systems Operation, Testing andAdjusting, “Power Train Pressures”.

• Replace the torque converter inlet reliefvalve. Refer to Disassembly and Assembly,RENR5138, “Power Train”.

8. The torque converter outlet pressure is outsidespecifications.

• Check the torque converter outlet pressure.Refer to Systems Operation, Testing andAdjusting, “Power Train Pressures”.





10. The torque converter lockup clutch may not befunctioning correctly.

• Test the correct function of the torque converterlockup clutch. Refer to Systems Operation,Testing and Adjusting, “Transmission HydraulicControl - Test and Adjust”.

The Transmission Does Not ShiftSmoothly

Possible Cause



2. The primary pressures for the transmissionclutches may be incorrect.

• Test the primary pressures for the transmissionclutches. Refer to Systems Operation, Testingand Adjusting, “Transmission Hydraulic Control- Test and Adjust”.

• Adjust the primary pressures for thetransmission clutches if the primary pressuresare incorrect.

51Power Train








5. The torque converter lockup clutch may still beengaged during shifts.

• Check the correct operation of thetorque converter lockup clutch. Refer toSystems Operation, Testing and Adjusting,“Transmission Hydraulic Control”.

6. The transmission may be operating in anelevated shift point mode.

• Check the correct function of the ECM and theinputs to the ECM. Refer to Systems Operation,Testing and Adjusting, RENR3442, “PowerTrain Electronic Control System”.

7. There may be a fault with the controlled throttleshifting function.

• Investigate the correct functioning of thecontrolled throttle shifting. Refer to SystemsOperation, Testing and Adjusting, RENR3442,“Power Train Electronic Control System”.

The Transmission Hesitates DuringShifting

Possible Cause

1. One or more individual valves for the transmissionclutches may not be functioning correctly.

• Test the individual valves for the transmissionclutches. Refer to Systems Operation, Testingand Adjusting, “Transmission Hydraulic Control- Test and Adjust”.







4. The power train oil level is outside thespecification.


5. The seals on the piston in the transmission clutchmay be leaking.

• Check the pressure of the oil in the clutch underfull engagement. Refer to Systems Operation,Testing and Adjusting, “Transmission HydraulicControl - Test and Adjust”.






7. The torque converter lockup clutch may notengage correctly after a shift.


• Check the correct operation of the torqueconverter lockup clutch.

• Inspect the torque converter lockup clutch fordamage. Refer to Disassembly and Assembly,RENR5138, “Torque Converter - Disassembleand Assemble”.

i01528148

Interaxle DifferentialTroubleshootingSMCS Code: 3287-035



Prior to carrying out troubleshooting on the interaxledifferential lock, use Caterpillar ET in order todiagnose any fault codes that may be present. Referto Systems Operation, Troubleshooting, Testingand Adjusting, RENR3442, “Power Train ElectronicControl System”.

If fault codes are present, repair the source of thefault code.

The Interaxle Differential Does NotEngage

Possible Causes

1. The hoses or the lines in the hydraulic system forthe output transfer gears may be damaged.

• Inspect the condition of the lines. Refer toSystems Operation, Testing and Adjusting,“Visual Inspection”.

2. The electrical circuit for the interaxle differentiallock may have a blown fuse, or there may be afaulty switch or a damaged wire.

• Check the circuit. If there is a blown fuse,replace the blown fuse. Refer to Operationand Maintenance Manual, SEBU7498, “Fuses- Replace” and Schematic, RENR5136,“Electrical Systems”. If there is damage to thewiring harness, repair the damage. If there is afaulty switch, replace the faulty switch.

3. The oil supply to the solenoid and relief valvemay not be sufficient.

• Test the oil supply to the solenoid and reliefvalve . Refer to Systems Operation, Testingand Adjusting, “Interaxle Differential - Test”.

4. The solenoid that controls the interaxle differentialin the solenoid and relief valve is not functioningcorrectly.

• Test the solenoid for correct operation. Referto Systems Operation, Testing and Adjusting,“Interaxle Differential - Test”.

5. The seals on the piston in the interaxle differentialmay be leaking.

• The pressure of the oil in the interaxledifferential may be lower than the specification.Check the pressure of the oil when theinteraxle differential is engaged. Refer toSystems Operation, Testing and Adjusting,“Power Train Pressures”.

6. There is debris or damaged components in theinteraxle differential or in the transfer gear.

• Inspect the oil filter and inspect the magneticscreen for debris.

• Determine the origin of the debris and repairor replace the damaged component.

• Change the oil. Clean the magnetic screenand install a new Caterpillar oil filter.

7. The disks and plates of the interaxle differentialmay be worn or damaged.

• Inspect the condition of the disks and platesin the interaxle differential. Replace the disksand the plates if the disks and the plates areworn or damaged. Refer to Disassembly andAssembly, RENR5139, “Power Train”.

The Interaxle Differential Does NotDisengage

A failure of the interaxle differential can cause windup in the power train. This may be noticeable as anincrease in the effort of steering.

53Power Train


Possible Causes

1. The solenoid that controls the interaxle differentialin the solenoid and relief valve may be sticking.

• Check the operation of the solenoid. Referto Systems Operation, Testing and Adjusting,“Interaxle Differetial - Test”.

• Check the pressure of the oil for the interaxledifferential when the interaxle differential isunselected. Refer to Systems Operation,Testing and Adjusting, “Interaxle Differential- Test”.

2. There is debris or damaged components in theinteraxle differential or in the transfer gear.

• Inspect the oil filter and inspect the magneticscreen for debris.

• Determine the origin of the debris and repairor replace the damaged component.

• Change the oil. Clean the magnetic screenand install an new Caterpillar oil filter.

3. The piston in the interaxle differential may besticking.

• Check the oil pressure in the interaxledifferential when the interaxle differential isunselected. Refer to Systems Operation,Testing and Adjusting, “Power Train Pressures”. If the oil pressure is normal, the piston maybe sticking. Inspect the lockup clutch forcorrect operation. Refer to Disassembly andAssembly, RENR5139, “Power Train”.

i01528161

Differential TroubleshootingSMCS Code: 3258-035



Prior to carrying out troubleshooting on the axledifferential locks, use Caterpillar ET in order todiagnose any fault codes that may be present. Referto Systems Operation, Troubleshooting, Testingand Adjusting, RENR3442, “Power Train ElectronicControl System”.

All Three Axle Differentials Will NotLock When The Axle DifferentialLocks Are Engaged

Possible Causes

1. The electrical circuit for the interaxle differentiallock may have a blown fuse, or there may be afaulty switch or a damaged wire.

• Check the circuit. If there is a blown fuse,replace the blown fuse. Refer to Operationand Maintenance Manual, SEBU7498, “Fuses- Replace” and Schematic, RENR5136,“Electrical Systems”. If there is damage to thewiring harness, repair the damage. If there is afaulty switch, replace the faulty switch.

2. The oil supply to the solenoid and relief valvethat is located on the output transfer gears maynot be sufficient.

• Test the oil supply to the solenoid and reliefvalve. Refer to Systems Operation, Testing andAdjusting, “Interaxle Differential - Test”.

3. The oil supply to the solenoid valve for the axledifferentials may not be sufficient.

• Test the solenoid for the interaxle differentiallock in the solenoid and relief valve for correctoperation. Refer to Systems Operation, Testingand Adjusting, “Interaxle Differential - Test”.

4. The solenoid for the axle differential locks inthe solenoid and relief valve is not functioningcorrectly.

• Test the solenoid for correct operation. Referto Systems Operation, Testing and Adjusting,“Differential - Test”.

5. There may be leaks in the oil lines to thedifferentials.

• Visually inspect the lines to the differentials.Refer to Systems Operation, Testing andAdjusting, “Visual Inspection”.

6. The seals on the piston in the differential locksmay be leaking. An oil line inside the axle maybe leaking.

• Check the level of the oil in the axle. Refer toTesting and Adjusting, “Visual Inspection”.

7. The disks and plates of the clutch on thedifferential locks may be worn or damaged.


• Inspect the condition of the disks and platesin the differential. Replace the disks and theplates if the disks and the plates are damagedor worn. Refer to Disassembly and Assembly,RENR5139, “Power Train”.

The Axle Differential On One OrMore Axles Will Not Lock When TheDifferential Lock Switch Is Engaged

Possible Causes

1. There may be leaks in the oil lines to thedifferential.

• Visually inspect the lines to the differential.Refer to Systems Operation, Testing andAdjusting, “Visual Inspection”.

• Visually inspect the lines to the output transfergears. Refer to Systems Operation, Testingand Adjusting, “Visual Inspection”.

2. The seals on the piston in the differential lockmay be leaking. An oil line inside the axle maybe leaking.

• Check the level of the oil in the axle. Refer toTesting and Adjusting, “Visual Inspection”.

• Visually inspect the lines to the output transfergears. Refer to Systems Operation, Testingand Adjusting, “Visual Inspection”.

3. The disks and plates of the clutch on thedifferential lock may be worn or damaged.

• Inspect the condition of the disks and theplates in the differential. Replace the disksand the plates if the disks and the plates areworn or damaged. Refer to Disassembly andAssembly, RENR5139, “Power Train”.

4. An axle shaft may be damaged or broken.

• Check the condition of the axle shaft onthe axle that will not lock. Replace theaxle shaft if the axle shaft is not within thespecification. Refer to Disassembly andAssembly, RENR5139, “Power Train”.

55Power Train


Testing and Adjusting

i01579055

Power Train PressuresSMCS Code: 3000-PX

Personal injury or death can result from suddenmachine movement.

Sudden movement of the machine can cause in-jury to persons on or near the machine.

Prevent possible injury by performing the proce-dure that follows before working on the machine.

NOTICEDo not connect or disconnect hose fittings to or fromthe quick disconnect nipples when there is pressure inthe system. This will prevent damage to the seals thatare in the fitting.

Refer to Systems Operation, Testing and Adjusting,“Machine Preparation For Troubleshooting”before you perform any testing and adjusting ortroubleshooting.

Before you carry out any testing, ensure thatyou have read the procedure and that you haveunderstood the procedure.

Note: Make sure that the filters and the screens areclean before you test any pressures. Make surethat the oil is at operating temperature before youperform these tests.

Table 4

Required Tools

PartNumber Description Qty

1U-5481 Pressure Gauge Group 1

1U-5482 Pressure Adapter Group 1

8T-5200 Generator and CounterSignal Group 1

FT-2796 Connector Harness 1

It will be necessary to raise the cab in order to gainaccess to the various pressure test points for thepower train. The guards beneath the engine andthe transmission may require lowering.

Torque Converter Pressures

Testing the Pilot Pressure for the TorqueConverter Lockup Clutch

1. Ensure that the engine is stopped and thatthe parking brake control is in the ENGAGEDposition.

2. Raise the cab. Refer to Operation andMaintenance Manual, SEBU7498, “Cab - Tilt”.


3. Remove the plug from test point (1). Install thecorrect fitting and the correct hose assemblyfrom the 1U-5482 Pressure Adapter Group intotest point (1). Attach the opposite end of thehose assembly to the 0 to 4000 kPa (0 to 580 psi)pressure gauge in the 1U-5481 Pressure GaugeGroup.


4. Disconnect the wiring harness from upshiftsolenoid (2), downshift solenoid (3) and torqueconverter lockup clutch solenoid (4).

5. Connect the wiring harness from the downshiftsolenoid to the torque converter lockup clutchsolenoid.

6. Lower the cab. Take care to ensure that thehose assembly is not trapped when the cab islowered.


7. Ensure that the transmission control is in theNEUTRAL position and that the parking brakeis engaged. Press and hold the service brakepedal.

8. Start the engine and run the engine at low idle.

9. Observe the pressure gauge. With the oil atnormal operating temperature, the pilot oilpressure for the torque converter lockup clutchmust be within the values that are shown in Table7.

10. Stop the engine and raise the cab. Removethe fitting and the hose from test point (1) andreplace the plug.

11. Reconnect the wiring harness correctly to theupshift solenoid, the downshift solenoid and thetorque converter lockup clutch solenoid.

Testing the Initial Pressure for the TorqueConverter Lockup Clutch

The pressure in the torque converter lockupclutch can be measured at test point (D) on thetransmission pressure control valve.



3. Remove the transmission cover from the top ofthe transmission.


Modulating Valve for the Torque Converter Lockup Clutch

4. Remove load piston plug (5).

Note: Care must be taken in order to ensure that theplug is not dropped into the transmission.


5. Remove the small cover from the transmissioncover.


6V-6064 Transmission Test Cover

6. Install the 6V-6064 Transmission Test Cover inthe place of the small cover. Use four bolts tohold the test cover in position.

7. Replace the transmission cover on the top ofthe transmission. Use four bolts to hold the testcover in position.


57Power Train


8. Install the correct hose assembly from the1U-5482 Pressure Adapter Group to test point(D). Use a suitable 90� fitting. Attach the oppositeend of the hose assembly to the 4000 kPa(580 psi) pressure gauge in the 1U-5481Pressure Gauge Group.


9. Disconnect the wiring harness from downshiftsolenoid (2), upshift solenoid (3) and torqueconverter lockup clutch solenoid (4).

10. Connect the wiring harness for the downshiftsolenoid to the torque converter lockup clutchsolenoid.


12. Ensure that the transmission control is in theNEUTRAL position and that the parking brakeis engaged. Press the service brake pedal andhold the service brake pedal.


14. Observe the pressure gauge. With the oil atnormal operating temperature, the initial oilpressure for the torque converter lockup clutchmust be within the values that are shown in Table7.

15. Stop the engine and raise the cab. Remove thefitting and the hose from test point (D).

16. Remove the transmission cover with the6V-6064 Transmission Test Cover from the topof the transmission.

17. Replace load piston plug (5).


18. Remove the 6V-6064 Transmission Test Coverfrom the transmission cover and install the smallcover to the transmission cover.

19. Replace the transmission cover.


Testing the Torque Converter LockupClutch Pressure

The pressure in the torque converter lockupclutch can be measured at test point (D) on thetransmission pressure control valve.




3. Remove the small cover from the transmissioncover on the top of the transmission planetary.






5. Install the correct hose assembly from the1U-5482 Pressure Adapter Group to test point(D) on the pressure control valve. Use a suitable90� fitting. Attach the opposite end of the hoseassembly to the 0 to 4000 kPa (0 to 580 psi)pressure gauge in the 1U-5481 Pressure GaugeGroup.



7. Connect the wiring harness for the downshiftsolenoid to the torque converter lockup clutchsolenoid.




11. Observe the pressure gauge. With the oil atnormal operating temperature, the maximum oilpressure for the torque converter lockup clutchmust be within the values that are shown in Table7.

12. Stop the engine and raise the cab. Remove thefitting and the hose from test point (D).

13. Remove the 6V-6064 Transmission Test Cover.

14. Replace the small cover on the top of thetransmission.


Inlet Relief Pressure for the TorqueConverter


The relief pressure of the torque converter inletcan be measured at test point (6). Test point (6) islocated on the left side of the transmission.

59Power Train




3. Disconnect the fitting (6). Install a suitableswivel tee between fitting (6) and the line to thetransmission pump drive housing. Install thecorrect fitting and the correct hose assemblyfrom the 1U-5482 Pressure Adapter Group tothe swivel tee. Attach the opposite end of thehose assembly to the 0 to 4000 kPa (0 to 580 psi)pressure gauge in the 1U-5481 Pressure GaugeGroup.


5. Ensure that the transmission control is in theNEUTRAL position and that the parking brakeis engaged. Press and hold the service brakepedal.

6. Start the engine and operate the engine at lowidle. Observe the pressure gauge. With the oilat normal operating temperature, the main reliefpressure must be within the values that areshown in Table 7.

7. Operate the engine at high idle. Observe thepressure gauge. With the oil at normal operatingtemperature, the torque converter inlet pressuremust be within the values in Table 7.

8. Stop the engine and raise the cab. Remove thefitting and the hose from the swivel tee andremove the swivel tee from fitting (6). Reconnectthe line to fitting (6).

Pressures For The TransmissionHydraulic Control System


Testing the Pressure for the TransmissionOil Pump


The pressure of the oil from the transmission oilpump is regulated by the main relief valve in thetransmission selector and pressure control valve.The main relief pressure for the transmissionhydraulic control can be measured at test point (7)on the right side of the transmission.



3. Install the correct hose assembly from the1U-5482 Pressure Adapter Group on testpoint (7). Attach the opposite end of the hoseassembly to the 0 to 4000 kPa (0 to 580 psi)pressure gauge in the 1U-5481 Pressure GaugeGroup.


5. Start the engine and operate the engine at lowidle. Observe the pressure gauge. With the oil atnormal operating temperature, the relief pressurefor the transmission hydraulic control must bewithin the values that are shown in Table 7.

6. Operate the engine at high idle. Observethe pressure gauge. With the oil at normaloperating temperature, the relief pressure for thetransmission hydraulic control must be within thevalues that are shown in Table 7.

7. Stop the engine and raise the cab. Remove thehose from test point (7).


Testing the Pilot Pressure for theTransmission Hydraulic Control System


The pilot oil pressure for the transmission hydrauliccontrol can be measured at test point (8) on theselector and pressure control valve.








5. Install the 6V-6064 Transmission Test Cover tothe transmission cover in the place of the smallcover. Use four bolts to hold the test cover inposition.

6. Remove the plug from test point (8). Install thecorrect fitting and the correct hose assemblyfrom the 1U-5482 Pressure Adapter Group ontest point (8).

7. Feed the hose through an opening in the6V-6064 Transmission Test Cover. To preventthe spraying of oil, use a piece of plastic oruse a piece of paper with the cover. Attachthe opposite end of the hose assembly to the0 to 4000 kPa (0 to 580 psi) pressure gauge inthe 1U-5481 Pressure Gauge Group.

8. Replace the transmission cover on the top of thetransmission.




12. Observe the pressure gauge. With the oil atnormal operating temperature, the pilot oilpressure for the transmission hydraulic controlsystem must be within the values that are shownin Table 7.

13. Stop the engine and raise the cab.

14. Remove the transmission cover with the6V-6064 Transmission Test Cover from the topof the transmission.

61Power Train


15. Remove the fitting and the hose from test point(8) and replace the plug.




Testing the Initial Pressures for theIndividual Transmission Clutches





4. Remove seven load piston plugs (9) from theindividual valves.

Note: Ensure that the plugs are not dropped intothe transmission.








Installation of the test gauges for pressure

(A) Test Point for Clutch 3(B) Test Point for Clutch 1(C) Test Point for Clutch 2(D) This pressure tap is used for the torque converter lockup clutch.(E) Test Point for Clutch 5(F) Test Point for Clutch 4(G) Test Point for Clutch 6(H) Test Point for Clutch 7

7. Install 6V-4143 Coupler, 3B-6552 Elbow,6V-3079 Hose, 6V-4142 Fitting, 6V-4144Coupler and 8T-0855 Pressure Gauge to testpoints (A), (B), (C), (E), (F), (G), and (H).

8. Disconnect the drive shaft to the front axle fromthe output yoke of the output transfer gear.Refer to Disassembly and Assembly, RENR5139,“Power Train”. Retract the drive shaft away fromthe output yoke and secure the drive shaft.

9. Disconnect the drive shaft between the outputtransfer gear and the hitch from the output yokeof the output transfer gear. Refer to Disassemblyand Assembly, RENR5139, “Power Train”. Retractthe drive shaft away from the output yoke andsecure the drive shaft.

10. Remove the wiring harness from the twotransmission output speed sensors. Connect a8T-5200 Signal Generator to the speed sensors.Use a FT-2796 Connector Harness.

11. Route the FT-2796 Connector Harness so thatthe signal generator can be mounted in the cab.

12. Lower the cab. Ensure that the hoses to thegauges and the connector harness is nottrapped.

13. Ensure that the parking brake control is in theENGAGED position.


15. Increase the engine speed to high idle.

16. Observe the pressure gauges for thetransmission clutches that are used in NEUTRAL.Refer to Tables 5 and 6. With the oil at normaloperating temperature, the primary pressurefor the oil in the transmission clutches must bewithin the values that are shown in Table 8.

17. Decrease the engine speed to low idle.

18. Move the transmission control to the DRIVEposition.


20. Observe the gauges for the transmission clutchthat is used in FIRST gear. Refer to Tables 5 and6. With the oil at normal operating temperature,the initial pressure for the oil in the transmissionclutch must be within the values that are shownin Table 8.


22. Start the signal generator. Refer to SpecialInstruction, SEHS8579, “Use of 8T-5200 SignalGenerator / Counter Group”.

23. Increase the frequency of the signal from thesignal generator until the transmission shifts fromfirst gear to second gear.


25. Observe the gauges for the transmissionclutches that are used in SECOND gear. Refer toTables 5 and 6. With the oil at normal operatingtemperature, the initial pressure for the oil in thetransmission clutches must be within the valuesthat are shown in Table 8.


27. Increase the frequency of the signal from thesignal generator and observe the initial pressuresfor each transmission gear.

28. Once the transmission is in SEVENTH gear andthe pressures have been obtained for eachclutch, reduce the frequency of the signal fromthe signal generator until the output is zero.

29. Move the transmission control to the REVERSEposition. Increase the engine speed to high idleand observe the clutch pressures.


31. Move the transmission control to the NEUTRALposition and stop the engine.

63Power Train


32. Compare the actual initial pressures that wererecorded with the pressures that are providedin Table 8.

33. After the pressures are recorded, remove thetest equipment and remove the transmissioncover from the top of the transmission.

34. Replace load piston plugs (9).




37. Replace the drive shafts to the machine. Refer toDisassembly and Assembly, RENR5139, “PowerTrain”.

Testing the Maximum Pressures for theTransmission Clutches



2. Remove the small cover from the large cover.





Installation of the test gauges for pressure

(A) Test Point for Clutch 3(B) Test Point for Clutch 1(C) Test Point for Clutch 2(D) This pressure tap is used for the torque converter lockup clutch.(E) Test Point for Clutch 5(F) Test Point for Clutch 4(G) Test Point for Clutch 6(H) Test Point for Clutch 7

4. Install 6V-4143 Coupler, 3B-6552 Elbow,6V-3079 Hose, 6V-4142 Fitting, 6V-4144Coupler and 8T-0855 Pressure Gauge to testpoints (A), (B), (C), (E), (F), (G), and (H).



5. Disconnect the wiring harness from torqueconverter lockup clutch solenoid (4).

Note: This will allow the testing of transmissionclutch pressures in torque converter drive withoutdisconnecting the drive shaft from the transmissionplanetary.

6. Remove the wiring harness from the twotransmission output speed sensors. Connect a8T-5200 Signal Generator to the speed sensors.Use a FT-2796 Connector Harness.


8. Lower the cab. Ensure that the hoses to thegauges and the connector harness is nottrapped.

9. Ensure that the parking brake control is in theENGAGED.



12. Observe the pressure gauges for thetransmission clutches that are used in NEUTRAL.Refer to Tables 5 and 6. With the oil at normaloperating temperature, the maximum pressurefor the oil in the transmission clutches must bewithin the values that are shown in Table 9.


14. Press and hold the service brakes.

15. Move the transmission control to the DRIVEposition.

Note: The engine will be turning against the torqueconverter, so there may be some small movementand vibration of the machine.


17. Observe the gauges for the transmissionclutch that is used in FIRST gear. Refer toTables 5 and 6. With the oil at normal operatingtemperature, the maximum pressure for the oil inthe transmission clutch must be within the valuesthat are shown in Table 9.


19. Start the signal generator. Refer to SpecialInstruction, SEHS8579, “Use of 8T-5200 SignalGenerator / Counter Group”.

20. Increase the frequency of the signal from thesignal generator until the transmission shifts fromfirst gear to second gear.


22. Observe the gauges for the transmissionclutches that are used in SECOND gear. Refer toTables 5 and 6. With the oil at normal operatingtemperature, the maximum pressure for the oilin the transmission clutches must be within thevalues that are shown in Table 9.


24. Increase the frequency of the signal from thesignal generator and observe the maximumpressures for each transmission gear at high idle.

25. Once the transmission is in SEVENTH gear andthe pressures have been obtained for eachclutch, reduce the frequency of the signal fromthe signal generator until the output is zero.

26. Move the transmission control to the REVERSEposition.

27. Increase the engine speed to high idle andobserve the clutch pressures.



30. Compare the actual clutch pressures that wererecorded with the pressures that are providedin Table 9.

31. After the pressures are recorded, remove thetest equipment.

65Power Train




33. Reconnect the wiring harness to the torqueconverter lockup clutch solenoid.

Testing the Upshift Pressure


The upshift pressure can be measured at test point(10) on the right side of the transmission.



3. Ensure that the transmission shift lever is in theNEUTRAL position.



5. Connect the wiring harness for upshift solenoid(2) to the downshift solenoid (3) and connect thewiring harness for the downshift solenoid to theupshift solenoid.

6. Lower the cab and start the engine. Ensure thatthe parking brake is engaged.


8. Start the engine and operate the engine at lowidle. The transmission will upshift through thegears to SEVENTH gear.

9. Observe the pressure gauge. With the oil atnormal operating temperature, the pressure ofthe upshift oil must be within the values that areshown in Table 7.



12. Remove the hose and the gauges from testpoint (10).


Testing the Downshift Pressure


The downshift pressure can be measured at testpoint (11) on the right side of the transmission.



3. Start the engine and operate the engine at lowidle. Observe the pressure gauge. With the oil atnormal operating temperature, the pressure ofthe downshift oil must be within the values thatare shown in Table 7.


5. Remove the hose and the gauges from test point(11).

Testing the Transmission LubricationPressure


The pressure of the lubrication oil for thetransmission planetary can be measured at testpoint (12).




4. Start the engine.

5. With the transmission in NEUTRAL, run theengine at low idle. Record the pressure that isdisplayed on the gauge.

6. Run the engine at high idle and record thepressure that is displayed on the gauge. With theoil at normal operating temperature, the pressurefor the lubrication oil for the transmissionplanetary must be within the values that areshown in Table 7.

7. Stop the engine.

8. Raise the cab and remove the hose from testpoint (12).

Output Transfer Gears andDifferential Lock Pressures


Pressure test point for the oil to the output transfer gear and thedifferentials

The supply pressure for the output transfer gearcan be measured at test point (13).

67Power Train


Note: The pressure for the differential locks canalso be measured at test point (13). Ensurethat the interaxle differential lock and the axledifferential locks are not selected. This may causedamage to the gauge that is used to measure thepressure of the oil.


2. Start the engine and operate the engine at lowidle. Observe the pressure gauge. With the oil atnormal operating temperature, the pressure ofthe lubrication oil for the transfer gears must bewithin the values that are shown in Table 7.

3. Operate the engine at high idle. Observe thepressure gauge. With the oil at normal operatingtemperature, the pressure of the lubrication oilfor the transfer gears must be within the valuesin Table 7.

Shut off the engine.

The clutch pressure for the interaxle differential lockcan be measured at test point (13).


2. Start the engine and operate the engine at lowidle. Select the interaxle differential lock. Refer toOperation and Maintenance Manual, “DifferentialLock Control”. Observe the pressure gauge.With the oil at normal operating temperature, thepressure of the oil in the lockup clutch of theinteraxle differential must be within the valuesin Table 7.

3. Select the axle differential locks. Refer toOperation and Maintenance Manual, “DifferentialLock Control”. Observe the pressure gauge.With the oil at normal operating temperature,the pressure of the oil in the lockup clutches ofthe axle differentials must be within the valuesin Table 7.


The pressures in the individual axle differentials canbe measured.

Front Axle Differential


Line for the differential locks on the trailer

1. Disconnect line (14) to the rear axles and insert6V-9508 Face Seal Plug into the line. Plug theline in order to prevent contamination of the oil.


Line for the front axle differential lock

2. Disconnect line (15) from the elbow in the frontaxle. Insert 8T-8902 Tee between the line andthe elbow in the front axle.

3. Install the correct hose assembly from the1U-5482 Pressure Adapter Group on the8T-8902 Tee. Attach the opposite end of thehose assembly to the 0 to 4000 kPa (0 to 580 psi)pressure gauge in the 1U-5481 Pressure GaugeGroup.


5. Select the interaxle differential lock and selectthe axle differential lock.

6. Observe the pressure gauge. With the oil atnormal operating temperature, the oil pressure inthe clutch for the front axle differential must bewithin the values that are shown in Table 7.



Center Axle Differential



1. Disconnect line (15) from the elbow in the frontaxle and insert 6V-9508 Face Seal Plug into theline. Plug the fitting on the front axle in order toprevent contamination of the oil.


Line for the rear axle differential lock

2. Disconnect line (16) from the elbow in the rearaxle and insert 6V-9508 Face Seal Plug into theline. Plug the fitting on the center axle in order toprevent contamination of the oil.


Line for the center axle differential lock

3. Disconnect line (17) from the elbow in the centeraxle and insert 8T-8902 Tee between the lineand the elbow in the front axle.




7. Observe the pressure gauge. With the oil atnormal operating temperature, the oil pressure inthe clutch for the center axle differential must bewithin the values that are shown in Table 7.


Rear Axle Differential Lock



69Power Train


1. Disconnect line (15) from the elbow in the frontaxle and insert 6V-9508 Face Seal Plug into theline. Plug the fitting on the front axle in order toprevent contamination of the oil.


Line for the center axle differential lock

2. Disconnect line (17) from the elbow in the centeraxle and insert 6V-9508 Face Seal Plug into theline. Plug the fitting on the center axle in order toprevent contamination of the oil.


Line for the rear axle differential lock

3. Disconnect line (16) from the elbow in the rearaxle and insert 8T-8902 Tee between the lineand the elbow in the front axle.




7. Observe the pressure gauge. With the oil atnormal operating temperature, the oil pressurein the clutch for the rear axle differential must bewithin the values that are shown in Table 7.


Specifications For The OilPressures In The Power TrainTable 5

SPEED SELECTION


REVERSE speed 3 & 7

NEUTRAL 1

FIRST speed 2 & 6

SECOND speed 1 & 6

THIRD speed 3 & 6

FOURTH speed 1 & 5

FIFTH speed 3 & 5

SIXTH speed 1 & 4

SEVENTH speed 3 & 4

Table 6

Individual Valves for Transmission Clutches

Clutch Station

1 B

2 C

3 A

4 F

5 E

6 G

7 H


Table 7

Test Point Description Specified Value

1 Pilot Pressure for the Torque ConverterLockup Clutch

1655 ± 138 kPa (240 ± 20 psi)

D Primary Pressure For The TorqueConverter Lockup Clutch

965 ± 35 kPa (140 ± 5 psi)

D Pressure For The Torque ConverterLockup Clutch

2345 ± 70 kPa (340 ± 10 psi)

6 Relief Pressure for The TorqueConverter Inlet (High Idle)

530 ± 35 kPa (77 ± 5 psi)

6 Relief Pressure For The TorqueConverter Inlet (Low Idle)

115 ± 20 kPa (17 ± 3 psi)

7 Relief Pressure For The TransmissionHydraulic Control (High Idle)

3100 ± 70 kPa (450 ± 10 psi)

7 Relief Pressure For The TransmissionHydraulic Control (Low Idle)

2725 ± 70 kPa (395 ± 10 psi)

8 Pilot Pressure For The TransmissionHydraulic Control

1655 ± 135 kPa (240 ± 20 psi)

12 Transmission Lubrication Oil (Low Idle) 30 ± 10 kPa (4.5 ± 1.5 psi)

12 Transmission Lubrication Oil (High Idle) 270 ± 14 kPa (39 ± 2 psi)

13 Output Transfer Gear Lubricationand Differential Locks

240 ± 105 kPa (35 ± 15 psi)

13 Interaxle Differential Gear andDifferential Locks

2755 ± 345 kPa (400 ± 50 psi)

14,15, 16,17 Axle Differential Locks 2755 ± 345 kPa (400 ± 50 psi)

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Table 8

Initial Clutch Pressure

Station (1) “A” “B” “C” “E” “F” “G” “H”

Clutch No. 3 No. 1 No. 2 No. 5 No. 4 No. 6 No. 7

SpeedPosition

EngagedClutches Pressure Pressure Pressure Pressure Pressure Pressure Pressure

N 1 0

345 + 50 -35 kPa(50 + 7- 5 psi)

0 0 0 0 0

R 3 and 7517 + 50 -

100 kPa (75+ 7 - 15 psi)

0 0 0 0 0345 + 50 -35 kPa (50+ 7 - 5 psi)

1 2 and 6 0 0

462 + 50 -100 kPa(67 + 7 -15 psi)

0 0345 + 50 -35 kPa (50+ 7 - 5 psi)

0

2 1 and 6 0

345 + 50 -35 kPa(50 + 7- 5 psi)

0 0 0345 + 50 -35 kPa (50+ 7 - 5 psi)

0

3 3 and 6517 + 50 -

100 kPa (75+ 7 - 15 psi)

0 0 0 0345 + 50 -35 kPa (50+ 7 - 5 psi)

0

4 1 and 5 0

345 + 50 -35 kPa(50 + 7- 5 psi)

0

420 + 50 -100 kPa(61 + 7 -15 psi)

0 0 0

5 3 and 5517 + 50 -

100 kPa (75+ 7 - 15 psi)

0 0

420 + 50 -100 kPa(61 + 7 -15 psi)

0 0 0

6 1 and 4 0

345 + 50 -35 kPa(50 + 7- 5 psi)

0 0380 + 50- 100 kPa

(55 ± 7 psi)0 0

7 3 and 4517 + 50 -

100 kPa (75+ 7 - 15 psi)

0 0 0380 + 50- 100 kPa

(55 ± 7 psi)0 0

(1) Station “D” is not used.


Table 9

Maximum Clutch Pressure

Station (1) “A” “B” “C” “E” “F” “G” “H”

Clutch No. 3 No. 1 No. 2 No. 5 No. 4 No. 6 No. 7

SpeedPosition

EngagedClutches Pressure Pressure Pressure Pressure Pressure Pressure Pressure

N 1 0

2895 +240 -

100 kPa(420 + 35- 15 psi)

0 0 0 0 0

R 3 and 7

1760 + 240- 100 kPa(255 + 35 -

15 psi)

0 0 0 0 02930 ±280 kPa

(425 ± 40 psi)

1 2 and 6 0 0

1980 + 240- 100 kPa

(287 + 35 -15 psi)

0 02930 + 240 -100 kPa (425+ 35 - 15 psi)

0

2 1 and 6 0

2895 +240 -

100 kPa(420 + 35- 15 psi)

0 0 02930 + 240 -100 kPa (425+ 35 - 15 psi)

0

3 3 and 6

1760 + 240- 100 kPa(255 + 35 -

15 psi)

0 0 0 02930 + 240 -100 kPa (425+ 35 - 15 psi)

0

4 1 and 5 0

2895 +240 -

100 kPa(420 + 35- 15 psi)

0

1970 + 240- 100 kPa(286 + 35 -

15 psi)

0 0 0

5 3 and 5

1760 + 240- 100 kPa(255 + 35 -

15 psi)

0 0

1970 + 240- 100 kPa(286 + 35 -

15 psi)

0 0 0

6 1 and 4 0

2895 +240 -

100 kPa(420 + 35- 15 psi)

0 0

1450 + 240- 100 kPa(210 + 35 -

15 psi)

0 0

7 3 and 4

1760 + 240- 100 kPa(255 + 35 -

15 psi)

0 0 0

1450 + 240- 100 kPa(210 + 35 -

15 psi)

0 0

(1) Station “D” is not used.

73Power Train


i01545903

Transmission HydraulicControl - Test and AdjustSMCS Code: 3073-025; 3073-081

Transmission Hydraulic ControlSystem

Main Relief Pressure

Oil is supplied by the transmission oil pump that ismounted on the torque converter housing.

The oil from the pump passes through thetransmission oil filter that is mounted on the rightside of the engine.

The pressure of the oil that is supplied by thetransmission oil pump is controlled by the main reliefvalve that is located in the transmission selectorand pressure control valve.

Test the pressure of the oil from the transmissionoil pump. Refer to Systems Operation, Testing andAdjusting, “Power Train Pressures”. If the pressureof the oil from the transmission oil pump is lowerthan the specification at both low idle and at highidle, there may be a failure of the transmission oilpump. Alternatively, there may be damage to one ormore of the seals in the transmission clutches. Testthe individual clutches. Refer to Systems Operation,Testing and Adjusting, “Power Train Pressures”.

The transmission oil pump cannot be serviced. It isnecessary to replace the transmission oil pump.

If the pressure of the oil from the transmission oilpump is too low at low idle but correct at high idle,the setting of the relief valve may be too low.

If the pressure of the oil from the transmission oilpump is too high, the setting of the relief valve istoo high.


Adjustment of relief valve (1) is achieved by theaddition or removal of spacers (2).

The addition of spacers will increase the settingof the relief valve. The removal of spacers willdecrease the setting of the relief valve. Refer toTable 10 for the correct selection of spacers.

Table 10

Chart of Spacers for Adjustment of the Relief Valve (1)

Spacer Thickness Change inPressure

145-0105Spacer

0.25 mm(0.010 inch)

41 kPa (6.0 psi)

145-0106Spacer

0.90 mm(0.035 inch)

145 kPa(21.0 psi)

145-0107Spacer

1.60 mm(0.063 inch)

261 kPa(37.9 psi)

(1) Before an adjustment is made, ensure that the valve springis not weak or broken. Refer to Specifications, RENR5133,“Power Train”.


Pilot Pressure for the TransmissionHydraulic Control Valve


The pilot pressure for the transmission hydrauliccontrol valve is determined by priority reductionvalve (3).

Test the pilot pressure for the transmission hydrauliccontrol. Refer to Systems Operation, Testing andAdjusting, “Power Train Pressures”.

If the pressure is lower than the specification, thesetting of the priority reduction valve is too low.

If the pressure is higher than the specification, thesetting of the priority reduction valve is too high.

Adjustment of priority reduction valve (3) is achievedby the addition or removal of spacers (4).

The addition of spacers will increase the settingof the relief valve. The removal of spacers willdecrease the setting of the relief valve. Refer totable 10 for the correct selection of spacers.

Table 11

Chart of Spacers for the Adjustment of thePriority Reduction Valve (1)

Spacer Thickness Change inPressure

5M-3492 Spacer 0.25 mm(0.010 inch)

17 kPa (2.5 psi)

7M-1397 Spacer 0.91 mm(0.036 inch)

60 kPa (8.7 psi)

(1) Before an adjustment is made, ensure that the valve springis not weak or broken. Refer to Specifications, RENR5133,“Power Train”.

Testing the Function of the NeutralizerValve

The neutralizer valve prevents the transmissionfrom selecting a gear if the engine is started andthe selector spool is not in the NEUTRAL position.The following procedure may be used to test thefunction of the neutralizer valve.

1. Stop the engine and engage the parking brake.Raise the cab.

2. Ensure that the transmission shift lever is in theNEUTRAL position.

3. Disconnect the wiring harness from the upshiftand downshift solenoids and from the torqueconverter lockup clutch solenoid.


4. Remove the plug for the selector spool fromthe left side of the transmission case while theengine is stopped.

75Power Train


5. Use a 9S-1721 Extension (1/4 inch squaredrive) and a 9U-6635 Reversible Ratchet to turnthe transmission rotary selector spool. When theratchet is fully turned in a clockwise direction,the rotary selector spool is in the NEUTRALposition. The order of the detent positions isNEUTRAL, REVERSE, REVERSE 1, and FIRSTspeed through SEVENTH speed.

Note: Detent position REVERSE is not used in thisapplication.

Note: There is approximately 30 degrees of rotationbetween each detent of the rotary selector spool.

6. Rotate the selector spool to the FIRST speedposition.

7. Lower the cab and start the engine. Ensure thatthe service brakes are engaged.

8. Correct operation of the neutralizer valve willprevent the engagement of the clutches forFIRST speed regardless of the position of theselector spool.


10. Return the selector spool to the NEUTRALposition and replace the wiring harness to theupshift and downshift solenoids and from thetorque converter lockup clutch solenoid.

11. Replace the plug for the selector spool.

Torque Converter

The Torque converter is supplied with oil on twolevels. The torque converter is supplied with oil inorder to allow the transfer of power through thetorque converter. A separate circuit exists for thecontrol of the lockup function of the torque converterin order to provide direct drive from the engine tothe transmission.

Torque Converter Inlet Relief PressureTesting and Adjusting


The oil for the torque converter is supplied by thetransmission selector and pressure control valve.The pressure of this oil is regulated by the torqueconverter inlet relief valve (6).

Test the inlet relief pressure for the torque converter.Refer to Systems Operation, Testing and Adjusting,“Power Train Pressures”. If the inlet relief pressurefor the torque converter is incorrect , bench testthe torque converter inlet relief valve. If the settingof the torque converter inlet relief valve is incorrect,5M-9622 Shims can be added or removed frombehind the spring in the relief valve.

If the setting of the torque converter inlet relief valveis correct, but the pressure of the oil in the torqueconverter is lower than the specification, there maybe an incorrect supply of oil to the torque converterinlet relief valve. Test the setting of the main reliefvalve for the transmission hydraulic control system.

If the supply of oil to the torque converter inletrelief valve is satisfactory, there may be a problemwith the torque converter that allows oil to be lost.Remove the torque converter from the machine andinvestigate possible damage. Refer to Disassemblyand Assembly, RENR5139, “Power Train”.


Torque Converter Lockup Clutch

The torque converter lockup clutch is controlled bya modulating valve that is mounted on the pressurecontrol valve for the transmission.

The correct pressure for the torque converter lockupclutch is dependent upon the correct adjustmentand the correct operation of the modulating valvefor the torque converter lockup clutch.

The modulating valve for the torque converterlockup clutch is controlled by a pilot oil supply thatis controlled by the torque converter lockup clutchsolenoid.

To test the function of the solenoid valve for thetorque converter lockup clutch, test the pressureof the pilot oil from the solenoid valve. Refer toSystems Operation, Testing and Adjusting, “PowerTrain Pressures”. If the pressure of the pilot oilfrom the torque converter lockup clutch solenoid isoutside the specifications, there may be a fault withthe supply of oil to the solenoid.

Measure the main relief pressure for the transmissionhydraulic control.

If the main relief pressure for the transmissionhydraulic control is correct, there is a problem withthe torque converter lockup clutch solenoid.

Testing the Torque Converter Lockup ClutchSolenoid

1. Ensure that the machine is parked on a levelsurface and that the parking brake control isengaged.

2. Move the key start switch to the ON position. Donot start the engine.

3. Raise the cab.

4. Disconnect the wires from the upshift solenoid,the downshift solenoid and the torque converterlockup clutch solenoid.

5. Connect the harness from the downshift solenoidto the torque converter lockup clutch solenoid.

6. Use a tag wire to check that the solenoid coilis energized. If the tag wire is attracted to thesolenoid coil, this indicates that the solenoid coilis energized. If the tag wire does not indicatethat the solenoid coil is energized, the problemmay be in the electrical circuit.

7. If the solenoid does not appear to function,disconnect the connector for the solenoid valve.Check the resistance of the windings of the coilin the solenoid.

The resistance of the windings in the solenoidshould be 32.6 ± 1.6.

If the resistance of the windings is outside thespecifications replace the solenoid.

If the solenoid coil is energized, the problem maylie with the solenoid cartridge. The problem couldbe a bent solenoid stem, a spring that is weak orbroken, or a screen that is dirty or plugged.

If the torque converter lockup clutch solenoid isfunctioning correctly and the pilot oil supply to themodulating valve is correct, there is a problemwith the modulating valve for the torque converterlockup clutch.

Testing and Adjusting of the Modulating Valve forthe Torque Converter Lockup Clutch

The following tests are required in order todetermine the correct function of the modulatingvalve for the torque converter lockup clutch:

• Maximum pressure in the torque converter lockupclutch

• Initial pressure in the torque converter lockupclutch

• Correct Pressure decay in the clutch

Test the maximum pressure of the oil in thetorque converter lockup clutch. Refer to SystemsOperation, Testing and Adjusting, “Power TrainPressures”.

If there is no pressure in the torque converterlockup clutch, there may be a problem with thepilot supply to the modulating valve for the torqueconverter lockup clutch. Test the function of thetorque converter lockup clutch solenoid.

77Power Train



If the solenoid is functioning correctly and thepilot supply to the modulating valve is within thespecifications, load piston (8) or selector piston (9)may be sticking, or load piston spring (10) may beweak or broken. Remove the modulating valve andinspect the modulating valve for damage. Refer toDisassembly and Assembly, RENR5139, “PowerTrain”.

If the pressure in the torque converter lockup clutchis lower than the specification, there are a numberof possible causes.

• The initial pressure for the torque converterlockup clutch may be incorrect.

• Load piston plug (11) may not be installed.

• Load piston orifice (12) may be blocked.

• Load piston (8) may be sticking within selectorpiston (9).

• Load piston spring (10) may be broken or weak.

Test the initial pressure for the torque converterlockup clutch. Refer to Systems Operation, Testingand Adjusting, “Power Train Pressures”.

While the cover of the transmission is removed,check that load piston plug (11) is installed correctly.

If the initial pressure is correct and the loadpiston plug is installed correctly, the load pistonorifice could be blocked. it will be necessary toremove the modulating valve in order to inspect theinternal components for damage or for blockages.Disassembly and Assembly, RENR5139, “PowerTrain”

Testing and Adjusting the Initial Pressure for theTorque Converter Lockup Clutch

The problems that are listed above may alsocontribute to providing an incorrect initial pressure.

If the initial pressure is too low, the load pistonspring or the setting of the modulating valve maybe incorrect.


If the initial pressure is too high, it is probable thatthere is an incorrect load piston spring, or that thesetting of the modulating valve is incorrect.

Remove the modulating valve and inspect thespring. Measure the rate of the spring. Refer toSpecifications, RENR5133, “Power Train”.

If the rate of the spring is correct, shims (13) mustbe added or removed from behind the load pistonspring. Refer to Table 12 for the correct shims touse in order to adjust the initial pressure setting ofthe modulating valve.

Table 12

Chart of Shims for the Modulating Valve for theTorque Converter Lockup Clutch (1)

Pt. No. forShims

Thickness Change in InitialPressure

8J-4452 Shim 0.12 mm(0.005 inch)

10 kPa (1.5 psi)

2S-0675 Spacer 0.40 mm(0.016 inch)

32 kPa (4.7 psi)

9J-1330 Shim 0.79 mm(0.031 inch)

62 kPa (9.0 psi)

(1) Before an adjustment is performed, be certain that the valvesprings are not weak or broken.

Carry out the adjustment of the modulating valveand repeat the tests for initial pressure and formaximum pressure.


Testing the Transmission Clutches

Before testing and adjusting the individual valvesfor the transmission clutches, it is important todetermine that the various components of theselector and pressure control valve are functioningcorrectly. Perform the procedures that are providedearlier in this section in order to determine that themain relief pressure and the pilot pressure for thetransmission hydraulic control are correct.

Testing the Upshift and the DownshiftSolenoids

The upshift solenoid and the downshift solenoids aresupplied with oil by the transmission oil pump. Usethe following procedure in order to test the functionof the upshift solenoid and the downshift solenoid.

1. Connect suitable test gauges to the test pointsin order to test the upshift pressure and thedownshift pressure. Refer to Systems Operation,Testing and Adjusting, “Power Train Pressures”.

2. Connect a suitable gauge to the test point for thetransmission oil pump pressure. Refer to SystemsOperation, Testing and Adjusting, “Power TrainPressures”.


3. Disconnect the wires from torque converterlockup clutch solenoid (14).

4. Lower the cab. Take care to ensure that thehose assemblies are not trapped when the cabis lowered.

5. Start the engine. Run the engine at low idle inNEUTRAL.

6. Ensure that the parking brake is engaged andpress the service brake pedal.

7. Observe the gauges. The gauge for thetransmission oil pump pressure and for downshiftsolenoid (16) must read the same value. Thegauge for upshift solenoid (15) must read 0 kPa(0 psi).

If the gauge for the downshift solenoid doesnot read the same value as the gauge for thepressure at the transmission oil pump, there is afault with the downshift solenoid valve.

If the gauge for the upshift solenoid is readingthe same value as the gauge for the transmissionoil pump pressure, then there is a fault with theupshift solenoid valve.





10. With the key start switch in the ON position, usea tag wire to check that the solenoid coil of thedownshift solenoid is energized. If the tag wire isattracted to the solenoid coil, this indicates thatthe solenoid coil is energized. If the tag wire doesnot indicate that the solenoid coil is energized,the problem may be in the electrical circuit.

11. Connect the wiring for the upshift solenoid to thedownshift solenoid and connect the wiring for thedownshift solenoid to the upshift solenoid.

12. Lower the cab. Take care to ensure that thehose assemblies are not trapped when the cabis lowered.

13. Ensure that the parking brake is engaged andpress the service brake pedal.

14. Start the engine. Run the engine at low idle inNEUTRAL.

Note: The engine will be turning against the torqueconverter and the transmission will shift to SEVENTHgear.

15. Observe the gauges. The gauge for thetransmission oil pump pressure and for theupshift solenoid must read the same value. Thegauge for the downshift solenoid must read0 kPa (0 psi).

79Power Train


If the gauge for the upshift solenoid does notread the same value as the gauge for thetransmission oil pump pressure, there is a faultwith the upshift solenoid valve.

If the gauge for the downshift solenoid is readingthe same value as the gauge for the transmissionoil pump pressure, there is a fault with thedownshift solenoid valve.

16. Stop the engine.

17. Raise the cab.

18. With the key start switch in the ON position, usea tag wire to check that the solenoid coil of theupshift solenoid is energized. If the tag wire isattracted to the solenoid coil, this indicates thatthe solenoid coil is energized.




20. Return the wiring harness to the correctsolenoids. Disconnect the test gauges and lowerthe cab.

Testing and Adjusting the IndividualValves for Clutch Engagement

The correct engagement of the clutches inthe transmission planetary is dependent uponthe correct operation and adjustment of theindividual valve in the pressure control valve of thetransmission hydraulic control system.

Clutch engagement is dependent upon two factors,the supply of pilot oil to the individual valves in thepressure control valve and the supply of pressurizedoil for clutch engagement.

The supply of pilot oil to the individual valves iscontrolled by the selector spool in the selector andpressure control valve.

The following tests are required in order todetermine the correct function of the individualvalves for the transmission clutches:

• Maximum pressure in the transmission clutches

• Initial pressure in the transmission clutches

• Pilot pressure to the individual valves

Test the maximum pressure of the oil in thetransmission clutches. Refer to Systems Operation,Testing and Adjusting, “Power Train Pressures”.

If there is no pressure in the transmission clutches,there may be a problem with the pilot supply to thepressure control valve.

Testing the Pilot Supply for TransmissionClutches

Test the pressure of the pilot supply to the individualvalves. Refer to Systems Operation, Testing andAdjusting, “Power Train Pressures”.

If there is no pilot supply pressure to the individualvalves, the neutralizer valve may not be functioningcorrectly. Test the function of the neutralizer valve. Ifthe neutralizer valve is functioning correctly, theremay be a problem with the downshift solenoid orthe upshift solenoid.

If the neutralizer valve, the upshift solenoid and thedownshift solenoid are functioning correctly, theremay be a blockage in the screen that is inside theselector spool.


Remove the selector spool and clean the screen.

If the pilot supply to the individual valves is withinthe specifications, load piston (17) or selectorpiston (18) may be sticking, or load piston spring(19) may be weak or broken. Remove the individualvalve and inspect the components for damage.Refer to Disassembly and Assembly, RENR5139,“Power Train”.

If the pressure in the transmission clutch is lowerthan the specification, there are a number ofpossible causes.



• The initial pressure for the transmission clutchesmay be incorrect.

• Load piston plug (20) may not be installed.

• Load piston orifice (21) may be blocked.

• Load piston (17) may be sticking within selectorpiston (18).

• Load piston spring (19) may be broken or weak.

If problems occur with the engagement oftransmission clutches, it is first necessary to testthe primary pressures in the clutches. Refer toSystems Operation, Testing and Adjusting, “PowerTrain Pressures”.

If the initial pressures are correct and the loadpiston plugs are installed correctly, the load pistonorifice could be blocked. it will be necessary toremove the modulating valve in order to inspect theinternal components for damage or for blockages.Disassembly and Assembly, RENR5139, “PowerTrain”

Testing and Adjusting the Initial Pressure For TheTransmission Clutches

The problems that are listed above may alsocontribute to providing an incorrect initial pressure.

If the initial pressure is too low, the load pistonsprings may be incorrect, or the setting of themodulating valve may be incorrect.

If the initial pressure is too high, it is probable thatthere is an incorrect load piston spring, or that thesetting of the modulating valve is incorrect.

Remove the modulating valve and inspect loadpiston springs (19). Measure the rate of the springs.Refer to Specifications, RENR5133, “Power Train”.

If the rates of the springs are correct, shims (22)must be added or removed from behind the loadpiston spring. Refer to Table 13 for the correctshims to use in order to adjust the initial pressuresetting of the modulating valve.

81Power Train


Table 13

Shims for the Pressure Control ValvePressure Change per Shim

Station (1) A B C E F G H

Engaged Clutch 3 1 2 5 4 6 7

Thickness of Shim Pressurechange

Pressurechange

Pressurechange

Pressurechange

Pressurechange

Pressurechange

Pressurechange

5J-2721 Shim

0.13 mm (0.005 inch) 16 kPa(2.3 psi)

14 kPa(2.0 psi)

20 kPa( 2.9 psi)

17 kPa(2.5 psi)

14 kPa(2.0 psi)

17 kPa(2.5 psi)

17 kPa(2.5 psi)

6J-3993 Shim

0.25 mm (0.01 inch) 32 kPa(4.6 psi)

28 kPa(4.1 psi)

41 kPa(5.9 psi)

35 kPa(5.1 psi)

28 kPa(4.1 psi)

33 kPa(4.8 psi)

33 kPa(4.8 psi)

4M-1751 Spacer

0.41 mm (0.016 inch) 50 kPa(7.3 psi)

45 kPa(6.5 psi)

65 kPa(9.4 psi)

56 kPa(8.1 psi)

45 kPa(6.5 psi)

53 kPa(7.7 psi)

53 kPa(7.7 psi)

5J-1036 Shim

0.80 mm (0.031 inch) 98 kPa(14.2 psi)

87 kPa(12.6 psi)

125 kPa(18.2 psi)

109 kPa(15.8 psi)

87 kPa(12.6 psi)

103 kPa(14.9 psi)

103 kPa(14.9 psi)

(1) Station “D”is not used.

Table 14

Specifications and Identification of the Components of the Pressure Control Valve

Location of the LoadPiston Body (1)

A B C E F G H

Thickness Of TheLoad Piston Orifice

4.58 mm(0.180 inch)

2.54 mm(0.100 inch)

4.58 mm(0.180 inch)

4.58 mm(0.180 inch)

2.54 mm(0.100 inch)

4.58 mm(0.180inch)

4.58 mm(0.180inch)

Color of the OuterSpring Of the LoadPiston

Light bluecolor

Light greencolor

Yellow color Light bluecolor

Light bluecolor

Light bluecolor

Light bluecolor

Color of the InnerSpring Of the LoadPiston

Light greencolor

Light bluecolor

Light bluecolor

Yellow color Orangecolor

Light bluecolor

Light bluecolor

Size of the DecayOrifice

1.57 mm(0.062 inch)

1.98 mm(0.078 inch)

1.57 mm(0.062 inch)

1.98 mm(0.078 inch)

1.98 mm(0.078 inch)

1.57 mm(0.062inch)

-

Color of the DecayOrifice

Green color Red color Green color Red color Red color Greencolor

-

(1) The location of the load piston body is identical to the location for the valve.

Carry out the adjustment of the modulating valveand repeat the tests for initial pressure and formaximum pressure.


i01558815

Transmission Shift Points -TestSMCS Code: 3030-081

Table 15

Tools Needed Qty

8T-5200Generator andCounter Signal

Group1

FT-2796 ConnectorHarness

1



2. Disconnect the wiring harness from the torqueconverter lockup clutch solenoid (1).

Note: This will allow testing of the shift points for thetransmission without disconnecting the drive shaftfrom the transmission planetary.


3. Remove the wiring harness from the twotransmission output speed sensors (2). Connecta 8T-5200 Signal Generator to the twotransmission output speed sensors. Use aFT-2796 Connector Harness.


5. Lower the cab. Ensure that the connectorharness is not trapped.

6. Ensure that the parking brake control is in theENGAGED position.


7. Connect a computer with ET software to thediagnostics socket by using the communicationsadapter. The diagnostics socket is located at theright side of the seat for the operator.

8. Turn the engine start switch to the ON. Start theengine.

Switch on the computer and open up the ETsoftware.

9. Check that the computer detects the threeelectronic control modules.

10. Select “Transmission”.

11. Use ET in order to check that the service brakesand the parking brake are functioning correctly.

12. When you have ensured that the service brakesand the parking brake are functioning correctly,set ET to monitor the engine output speed, thetransmission output speed and the actual gear.


14. With the engine at low idle, move thetransmission control to the DRIVE position.

83Power Train


Note: The engine will be turning against the torqueconverter, so there may be some small movementand vibration of the machine.

15. Start the signal generator. Refer to SpecialInstruction, SEHS8579, “8T-5200 SignalGenerator”.

16. Observe the actual gear indicator.

17. Observe the computer and increase thefrequency of the signal from the signal generatoruntil the torque converter lockup clutch attemptsto engage. As the solenoid is not connected thiswill not occur. , It will be possible to observethe attempt of the ECM to engage the torqueconverter lockup clutch by using ET. Record thefrequency of the signal from the signal generatoras the ECM attempts to engage the torqueconverter lockup clutch. Refer to Table 16 andTable 17 for the correct shift points.

18. Increase the frequency of the signal from thesignal generator until the transmission shifts tosecond gear. Record the frequency of the signalfrom the signal generator as the transmissionshifts to second gear. Refer to Table 16 andTable 17 for the correct shift points.

19. Increase the frequency of the signal from thesignal generator and observe the shift points foreach of the transmission gears.

20. Once the transmission is in SEVENTH gear,reduce the frequency of the signal from the signalgenerator. Record the frequency of the signalfrom the signal generator as the transmissionmoves from SEVENTH gear to SIXTH gear.

21. Repeat this procedure for each gear until thetransmission is in FIRST gear.


23. Compare the shift points that were recordedwith the shift points that are provided in Table16 and Table 17.

The shift points for the transmission are modifiedwhen certain actions are carried out. Engagingthe brakes will result in the modification of thetransmission shift points. Table 16 contains thesemodified shift points.

Use the information in Table 16 for this procedure.

Table 17 provides the normal transmission shiftpoints.

Table 16

Modified Shift Points At Nominal Engine Speed

Upshift Signal GeneratorFrequency

1C to 1L 218

1 to 2 404

2 to 3 553

3 to 4 750

4 to 5 1008

5 to 6 1367

6 to 7 1843

Downshift Signal GeneratorFrequency

7 to 6 1422

6 to 5 1056

5 to 4 779

4 to 3 580

3 to 2 427

2 to1 312

1L to 1T 218

Table 17

Shift Point At Nominal Engine Speed

Upshift Signal GeneratorFrequency

1C to 1L 218

1 to 2 315

2 to 3 430

3 to 4 583

4 to 5 784

5 to 6 1063

6 to 7 1329

Downshift Signal GeneratorFrequency

7 to 6 1317

6 to 5 978

5 to 4 721

4 to 3 537

3 to 2 396

2 to1 289

1L to 1T 194


24. Once the test has been completed, remove theconnector harness from the transmission andreplace the wiring harness for the transmissionoutput speed sensors. Replace the wiringharness for the torque converter lockup clutchsolenoid.

i01522493

Interaxle Differential - TestSMCS Code: 3287-081

The interaxle differential lock is controlled by thesolenoid and relief valve group that is mountedon the transfer gear. The solenoid and relief valvegroup features a solenoid valve that controls the oilpressure to the interaxle differential lock and to thesolenoid valve that controls the oil pressure to theaxle differential locks. A relief valve is also includedin the solenoid and relief valve group in order toregulate the maximum oil pressure to the differentiallocks.


Prior to starting with checks on the interaxledifferential, use Caterpillar ET in order to diagnoseany fault codes that may be present. Refer toSystems Operation, Troubleshooting, Testing andAdjusting, RENR3442, “Power Train ElectronicControl System”.

Testing The Oil Supply To theInteraxle Differential


Test the supply pressure for the transfer gear at testpoint (1). Refer to Systems Operation, Testing andAdjusting, “Power Train Pressures”.

Select the interaxle differential lock and test thepressure of the oil at test point (1). Refer to SystemsOperation, Testing and Adjusting, “Power TrainPressures”.

If both pressures are below the specification, itis possible that relief valve (3) is not functioningcorrectly. Replace the relief valve and test the oilpressures again.

Testing The Solenoid


To test the function of solenoid (2) in the solenoidand relief valve group, run the engine at low idleand test the pressure at test point (1). Refer toSystems Operation, Testing and Adjusting, “PowerTrain Pressures”. Observe the gauge and select theinteraxle differential lock.

If a rise in the pressure is noted, then the solenoidis allowing oil to the interaxle differential lock.

If a pressure rise is noted, the solenoid and therelated electrical circuit are functioning correctly.

If there is no rise in the pressure, then the solenoidplunger is not moving.

If a pressure rise is not noted, use a tag wire tocheck that the solenoid coil is energized. If the tagwire is attracted to the solenoid coil, this indicatesthat the solenoid coil is energized. The problemis in the solenoid cartridge. The problem couldbe a bent solenoid stem, a screen that is dirty orplugged, or a spring that is weak or broken.

If the tag wire does not indicate that the solenoidcoil is energized, the problem may be in theelectrical circuit.

Test the interaxle differential lock. If the solenoiddoes not function correctly, the problem may lie withthe switch for the interaxle differential lock or withthe wiring harness of the machine.

85Power Train


If the solenoid does not appear to function,disconnect the connector for the solenoid valve.Check the resistance of the windings of the coil inthe solenoid.



Pressure In The InteraxleDifferential Lock

If the solenoid and relief valve group is functioningcorrectly and the pressure to the interaxle differentialis correct, a failure of the interaxle differential tolock could be due to leakage past the seals of theclutch. A failure could also be a result of damage tothe internal components of the interaxle differential.

Inspect the oil filter and the magnetic screenfor debris that may indicate damage to theinternal components of the clutch for the interaxledifferential. Refer to Systems Operation, Testing andAdjusting, “Visual Inspection”.

i01528327

Differential - TestSMCS Code: 3258-081


The axle differential locks are controlled by solenoidvalve (1) that is mounted on solenoid and reliefvalve group (2). The solenoid valve controls the flowof the oil from the solenoid and relief valve groupto the clutches for the axle differential locks whenthe solenoid is activated.


Prior to starting with checks on the axle differentials,use Caterpillar ET in order to diagnose any faultcodes that may be present. Refer to SystemsOperation, Troubleshooting, Testing and Adjusting,RENR3442, “Power Train Electronic Control System”.

Visually inspect the lines to the axle differentialsand inspect the components of the control system.Inspect the oil in the system for the transfer gear andthe differential locks. Refer to Systems Operation,Testing and Adjusting, “Visual Inspection”.

Testing The Oil Supply To The AxleDifferentials

The axle differential locks can only be selected ifthe interaxle differential lock is also selected. Oilto the solenoid valve for the axle differential locksis supplied by the solenoid valve for the interaxledifferential lock. Both the solenoid valves arelocated in the solenoid and relief valve group thatis mounted on the transfer gear.

Test the supply pressure to the solenoid and reliefvalve group. Refer to Systems Operation, Testingand Adjusting, “Interaxle Differential - Test”.

Test the operation of the solenoid in the solenoidand relief valve group that controls the interaxledifferential. Refer to Systems Operation, Testing andAdjusting, “Interaxle Differential - Test”.

If oil is being supplied to the solenoid valve, test thesolenoid valve for correct operation.

Testing the Solenoid

To test the solenoid valve that controls the axledifferentials, test the pressure of the oil supply to thesolenoid valve and test the pressure of the oil supplyfrom the solenoid valve to the axle differentials.

The solenoid valve for the axle differentials islocated above the oil filter for the transfer gear onthe inside of the front frame assembly.



1. Disconnect line (3) from the elbow in the frontaxle and insert 6V-9508 Face Seal Plug intothe line.


2. Disconnect line (4) and insert a suitableadapter and a suitable hose from the 1U-5482Pressure Adapter Group into the line. Attach theopposite end of the hose assembly to one of the0 to 3400 kPa (0 to 580 psi) pressure gauges inthe 1U-5481 Pressure Gauge Group.


3. Install the correct hose assembly from the1U-5482 Pressure Adapter Group on testpoint (5). Attach the opposite end of thehose assembly to one of the 0 to 3400 kPa(0 to 580 psi) pressure gauges in the 1U-5481Pressure Gauge Group.

4. Start the engine and operate the engine atlow idle. Select the interaxle differential lock.Observe the pressure gauges. The gauge that isconnected to line (4) should not read a pressure.With the oil at normal operating temperature,the correct pressure must be displayed on thegauge that is connected to test point (5). Referto Systems Operation, Testing and Adjusting,“Power Train Pressures”.

5. Select the axle differential locks. The pressurethat is displayed on the gauge that is connectedto the line (4) must rise to the same value as thepressure that is displayed on the gauge that isconnected to test point (5).

If the same pressure is displayed on both gauges,the solenoid valve is functioning correctly.

The solenoid valve is not functioning correctly ifa pressure is not displayed on the gauge that isconnected to the solenoid valve.

If a pressure rise is not noted, use a tag wire tocheck that the solenoid coil is energized. If the tagwire is attracted to the solenoid coil, this indicatesthat the solenoid coil is energized. The problem isin the solenoid valve. The problem could be a bentsolenoid stem, a screen that is dirty or plugged, ora spring that is weak or broken.

If the tag wire does not indicate that the solenoidcoil is energized, the problem may be in theelectrical circuit.

If the solenoid does not appear to function,disconnect the connector for the solenoid valve.Check the resistance of the windings of the coil inthe solenoid.


If the resistance of the solenoid windings is outsidethe specifications replace the solenoid.

If the resistance of the solenoid windings is withinthe specifications, the problem may lie with theswitch for the axle differential locks or with thewiring harness of the machine.

Testing The Pressure In The AxleDifferential Locks

Test the pressures for the individual axle differentiallocks. Refer to Systems Operation, Testing andAdjusting, “Power Train Pressures”.

If the pressure in an individual axle differential lockis observed to be lower than the specification, theremay be an internal leak in the axle. Check thelevel of the oil in the axle. Refer to Operation andManual, SEBU7498. If the level of the oil in the axleis higher than the specification, there may be a leakin the seals on the piston of the axle differential lockor there is a leak in the lines for the axle differentiallock that are inside the axle. Repair the seals orrepair the damaged line.

87Power Train


If the pressure in an individual axle differential lockis observed to be within the specification, the pistonin the axle differential lock clutch may be stickingor there may be damage to the plates and to thedisks in the axle differential lock. Inspect the oil inthe axle for debris that may indicate damage to theaxle differential lock. Refer to Systems Operation,Testing and Adjusting, “Visual Inspection”. Debris inthe oil may indicate damage to the axle differential.Remove the axle differential and inspect the axledifferential for damage. Refer to Disassembly andAssembly, RENR5139, “Differential - Disassembleand Assemble”.

88Power TrainIndex Section

Index

D

Differential - Test.................................................... 85Testing The Oil Supply To The AxleDifferentials ...................................................... 85

Testing The Pressure In The Axle DifferentialLocks................................................................ 86

Testing the Solenoid........................................... 85Differential (Center Axle) ....................................... 15Differential (Front and Rear Axle) .......................... 13Differential Troubleshooting ................................... 53

All Three Axle Differentials Will Not Lock WhenThe Axle Differential Locks Are Engaged......... 53

The Axle Differential On One Or More Axles WillNot Lock When The Differential Lock Switch IsEngaged........................................................... 54

F

Final Drive ............................................................. 18

G

General Information............................................... 5Tractor Arrangement .......................................... 5Trailer Arrangement ........................................... 5

General Troubleshooting Information .................... 42Graphic Color Codes ............................................. 4

I

Important Safety Information ................................. 2Interaxle Differential............................................... 11Interaxle Differential - Test ..................................... 84

Pressure In The Interaxle Differential Lock ........ 85Testing The Oil Supply To the InteraxleDifferential ........................................................ 84

Testing The Solenoid ......................................... 84Interaxle Differential Troubleshooting .................... 52

The Interaxle Differential Does Not Disengage.. 52The Interaxle Differential Does Not Engage ...... 52

M

Machine Preparation for Troubleshooting .............. 42

O

Operational Checks ............................................... 44Output Transfer Gears ........................................... 9

Output Transfer Gears Lubrication System ........... 28Charging and Scavenging Pump for the OutputTransfer Gears and Differential Locks .............. 28

Magnetic Screen for the Output Transfer Gears.. 29Oil Filter for the Output Transfer Gears .............. 29Solenoid and Relief Valve .................................. 29

P

Power Train Electronic Control System ................. 24Electronic Control Module.................................. 27Power Train Electronic Control System.............. 26Sensors In The Power Train ............................... 27

Power Train Hydraulic System............................... 19Output Transfer Gears and Differentials............. 22Torque Converter and Transmission .................. 19

Power Train Pressures........................................... 55Output Transfer Gears and Differential LockPressures ......................................................... 66

Pressures For The Transmission Hydraulic ControlSystem ............................................................. 59

Specifications For The Oil Pressures In The PowerTrain ................................................................. 69

Torque Converter Pressures .............................. 55Pressure Control Valve (Transmission).................. 30

Transmission Pressure Control Valve ................ 30

R

Rotary Actuator (Transmission) ............................. 40

S

Selector and Pressure Control Valve(Transmission) ..................................................... 37Neutralizer Valve ................................................ 38Priority Reduction Valve..................................... 38Relief Valve ........................................................ 39Rotary Selector Spool........................................ 38Torque Converter Inlet Relief Valve.................... 39

Systems Operation Section ................................... 4

T

Table of Contents................................................... 3Testing and Adjusting ............................................ 55Testing and Adjusting Section ............................... 42Torque Converter................................................... 6

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Index Section

Torque Converter Troubleshooting ........................ 45The Torque Converter Lockup Clutch DoesNot Disengage and the Engine Dies at LowSpeed............................................................... 46

The Torque Converter Lockup Clutch Does NotEngage............................................................. 45

The Torque Converter or the Transmission isOverheating...................................................... 45

Transmission Hydraulic Control ............................. 23Transmission Hydraulic Control - Test and Adjust.. 73

Testing the Transmission Clutches..................... 78Torque Converter ............................................... 75Transmission Hydraulic Control System ............ 73

Transmission Planetary ......................................... 8Transmission Planetary Troubleshooting ............... 47

Troubleshooting the Transmission...................... 47Transmission Shift Points - Test............................. 82Troubleshooting ..................................................... 42

V

Visual Inspection ................................................... 43

90Power TrainIndex Section

91Power Train

Index Section

269630396 systems operation testing and adjusting cat 740 articulated

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