Systems Operation Testing and Adjusting CAT 740 Articulated

RENR5134-01 July 2001

Systems Operation Testing and Adjusting 740 Articulated Truck Power Train AXM1-Up (Machine)

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Important Safety Information Most accidents that involve product operation, maintenance and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs. A person must be alert to potential hazards. This person 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 and could result in injury or death. Do not operate or perform any lubrication, maintenance or repair on this product, until you have read and understood the operation, lubrication, maintenance and repair information. Safety precautions and warnings are provided in this manual and on the product. If these hazard warnings 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 or pictorially presented. Operations that may cause product damage are identified by “NOTICE” labels on the product and in this publication. publication.

Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. The warnings 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 the product product will not be damaged damaged or be made unsafe unsafe by the operation, operation, lubrication, lubrication, maintenance maintenance or repair procedures that you choose. The information, specifications, and illustrations in this publication are on the basis of information that was 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 can affect the service that is given to the product. Obtain the complete and most current information before you start any job. Caterpillar dealers have the most current information available. For a list of the most current publication form numbers available, see the Service Manual Contents Microfiche, REG1139F.

When When replac replaceme ement nt parts parts are requir required ed for for this this product Caterpillar recommends using Caterpillar replac replaceme ement nt parts parts or parts parts with with equiva equivalen lentt specifications including, but not limited to, physical dimensions, type, strength and material. Failure to heed this warning can lead to premature failures, product damage, personal injury or death.

3 Power Train Table of Contents

Table of Contents Systems Operation Section Graphic Color Codes ...................... ................................ .................... ............ .. 4 General Information ..................... ............................... .................... ............... ..... 5 Torque Converter ..................... ............................... .................... .................. ........ 6 Transmission Planetary .................... .............................. .................... ............ 8 Output Transfer Gears .................... .............................. .................... ............ 9 Interaxle Differential ..................... ............................... .................... ............... ..... 11 Differential (Front and Rear Axle) ......................... 13 Differential (Center Axle) ................... ............................. .................... .......... 15 Final Drive .................... .............................. .................... .................... .................... .......... 18 Power Train Hydraulic System .................... ............................. ......... 19 Transmission Hydraulic Hydraulic Control .................... ........................... ....... 23 Power Train Electronic Control System ................. 24 Output Transfer Gears Lubrication System ........... 28 Pressure Control Valve (Transmission) (Transmission) ................. ................. 30 Selector and Pressure Control Valve (Transmissi (Transmission) on) ............................ .............. ............................. ......................... .......... 37 Rotary Actuator (Transmission) (Transmission) .................... ............................ ........ 40

Testing and Adjusting Section Troubleshooting Machine Preparation for Troubleshooting ............. 42 General Troubleshooting Troubleshooting Information .................... .................... 42 Visual Inspection .................... .............................. .................... .................... ............ 43 Operational Checks ..................... ............................... .................... ............... ..... 44 Torque Converter Troubleshooting ........................ ........................ 45 Transmission Planetary Troubleshooting .............. 47 Interaxle Differential Troubleshooting .................... .................... 52 Differential Troubleshooting Troubleshooting ..................... ............................... ............. ... 53 Testing and Adjusting Power Train Train Pressures .................... .............................. .................... ............ .. 55 Transmission ransmission Hydraulic Hydraulic Control Control - Test and and Adjust .. .. 73 Transmission Shift Points - Test ............................ 82 Interaxle Differential - Test .................................... 84 Differential - Test .................... .............................. .................... .................... ............ 85

Index Section Index .................... .............................. .................... .................... .................... ................... ......... 88

4 Power Train Systems Operation Section

Systems Operation Section i01481554

Graphic Color Codes SMCS Code: 4000

Illustration 1

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(A) Red ........................... Pump discharge pressure (B) Red Stripes and White Stripes .......................... First pressure reduction (C) Red Dots ................ Second pressure reduction (D) Orange ............................. Pilot system pressure (E) Orange Stripes and White Stripes .............. Reduced pilot system pressure (F) Blue .................................................. Blocked oil (G) Green .. Suction oil, return oil, and case drain oil (H) Yellow ..................................... Moving parts and activated valve sections (I) Purple ........................................ Pressurized gas (J) Gray ............................... Cutaway sections, and non-activated valve sections

5 Power Train Systems Operation Section i01563882

General Information SMCS Code: 3030

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Illustration 2 (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

Tractor Arrangement The engine flywheel drives torque converter (2). The torque converter has an integral lockup clutch. The lockup clutch for the torque converter allows the machine to operate in torque converter drive or in direct drive. Torque converter (2) is located within the housing for the transmission planetary which is bolted directly to the engine. Transmission planetary (3) contains seven hydraulically actuated clutches. The seven hydraulically actuated clutches give seven forward speeds and one reverse speed. Main drive shaft (17) transmits torque to output transfer gears and case (6). Differential (15) is located in output transfer gears and case (6), which is connected to front drive shaft (16) and drive shaft (7). Front drive shaft (16) is connected to differential and bevel gear (5). Drive shaft (7) is connected hitch drive shaft (8).

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

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

Trailer Arrangement Through hitch drive shaft (8) transmits torque to drive shaft (9). The drive shaft transfers drive to differential and bevel gear (10). Differential and bevel gear (10) transfers drive to wheel and final drives (14) for the center axle and drive shaft (11). Drive shaft (11) transmits torque to differential and bevel gear (12). Differential and bevel gear (12) transfers drive to wheel and final drives (13) for the rear axle.


Torque Converter SMCS Code: 3101

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Illustration 3 (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 engine flywheel. The torque converter consists of impeller (6), turbine (2), lockup clutch (7), and stator (3) which incorporates one-way clutch (5). The lockup clutch permits the machine to operate in direct drive in order to keep the power loss at a minimum. The one-way clutch holds the stator when torque converter drive is used. The one-way clutch allows the stator to turn freely when direct drive is used. The torque converter housing is fastened to the flywheel housing for the engine. Shaft (4) connects the torque converter to the transmission planetary group.

The engine flywheel turns rotating housing (1) and impeller (6). The impeller directs oil onto the blades of turbine (2). This causes the turbine to turn. The turbine directs the oil onto stator (3). This causes the stator to try to turn in the opposite direction of the turbine. The movement of the stator causes the rollers of one-way clutch (5) to move between stator (3) and the carrier for the stator. The action of the one-way clutch keeps the stator from rotating in the opposite direction to the turbine. The stator now directs most of the oil back to the impeller. The remainder of the oil goes out of the torque converter. The oil, that goes back to the impeller from the stator, moves in the same direction as the rotation of the impeller. Since this oil is moving in the same direction as the impeller, the torque output from the torque converter is multiplied. Turbine (2) turns hub (8). The hub turns shaft (4). Power is sent through the shaft to the transmission planetary group.

7 Power Train Systems Operation Section Lockup clutch (7) is part of the torque converter. The lockup clutch is located between the engine flywheel and the turbine. The lockup clutch is engaged under the following conditions: sufficient input speed to the transmission planetary group, sufficient oil pressure in the transmission planetary group, and sufficient engine rpm. When the lockup clutch is engaged, the impeller and the turbine turn at the same speed as the engine and there is no loss of power in the torque converter. The connection between the engine and the transmission planetary group is now direct. Torque converter drive is available in the first gear and reverse gear. The lockup clutch provides direct drive once the transmission speed and the engine speed are matched. Direct drive is provided in all the higher gears. The lockup clutch is disengaged during transmission shifts in order to allow a smooth transition between gears. The input speed of the torque converter is measured at the engine flywheel. This speed is the same speed as the engine output speed. The output speed of the torque converter is measured at the planetary transmission. This speed is the same speed as the transmission input speed.


Transmission Planetary SMCS Code: 3160

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Illustration 4 (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 forward speeds and one reverse speed. At lower ground speeds, FIRST speed uses torque converter drive. At higher ground speeds, FIRST speed uses direct drive. As the ground speed increases in FIRST speed the lockup clutch of the torque converter engages. This provides FIRST speed with direct drive. The torque converter is always in direct drive for speeds SECOND through SEVENTH, but there is a short period of torque converter drive when the clutches engage in the planetary transmission. Only torque converter drive is used when REVERSE speed is selected. The torque converter lockup clutch is disengaged during transmission shifts in order to provide smooth shifts. Table 1 shows the clutches 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

9 Power Train Systems Operation Section The planetary transmission consists of two rotating clutches, five stationary clutches, and five planetary units. This provides seven forward speeds and one reverse speed. No. 3 clutch (3) and No. 4 clutch (4) are the rotating clutches. The planetary transmission is bolted to the torque converter housing. Shaft (10) is part of the torque converter, and the shaft transmits the torque to the planetary transmission. Output yoke (9) from the planetary transmission is bolted to the main drive shaft. The main drive shaft connects the planetary transmission with the output transfer gear. Sensor (8) measures the output speed of the planetary transmission. There are two sensors in order to provide a backup in the event of a failure. The sensors send information about the transmission output speed to the ECM (Electronic Control Module). i01575760

Output Transfer Gears SMCS Code: 3159

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Illustration 5 (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

10 Power Train Systems Operation Section Power is transmitted to the output transfer gears from the transmission planetary group via a drive shaft to input shaft (1). The input shaft is splined to interaxle differential (2) that splits the torque between the front and the rear axles. Torque for the front axle is transmitted from the differential along shaft (3) to gear (4). An idler gear (5) transfers this torque to gear (6) in the bottom of the output transfer gear case. Gear (6) is splined to the output yoke (7). Torque for the rear axles is transmitted from the differential along shaft (8) to gear (9). Gear (9) is meshed with gear (10) which is splined to output yoke (11).

Illustration 6

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

Solenoid and relief valve (12) controls the lubrication oil for the output transfer gears. The solenoid and relief valve also controls the interaxle differential and the axle differentials.


Interaxle Differential SMCS Code: 3287

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Illustration 7 (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

Torque from the transmission planetary enters the output transfer gears, and flows directly to differential housing (4). The torque is transmitted through the interaxle differential to output shaft (8) and output shaft (9). The interaxle differential allows the torque from the transmission planetary to be divided between the front axle and the two rear axles. The front axle receives a smaller proportion of the torque than the center and rear axles. This prevents excess torque from being transmitted to the front axle. The distance from the axis of rotation of differential housing (4) to the axis of planetary gears (3) is greater than the distance to the axis of planetary gears (13).

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

Planetary gears (3) transfer the torque from differential housing (4) to output shaft (9) and planetary gears (13) transfer the torque from differential housing (4) to output shaft (8). The torque that is transmitted to output shaft (9) is greater than the torque that is transmitted to output shaft (8). Output shaft (9) transmits the torque to the two rear axles and output shaft (8) transmits the torque to the front axle. The torque that is transmitted to the two rear axles is greater than the torque that is transmitted to the front axle. 40% of the torque is transmitted to the front axle and 60% of the torque is transmitted to the center and the rear axle.

12 Power Train Systems Operation Section If the machine was operated on a hard surface with equal traction at each wheel, turning the machine would cause torsional stresses in the power train. This could reduce the service life of components in the power train. The interaxle differential transmits drive to the front and rear axles at equal speeds when the machine is travelling straight. The interaxle differential also transmits drive to the front and rear axles at different speeds when the machine is turning. Torque input is maintained at each axle throughout each operation. The interaxle differential responds to the difference in resistance between the front wheels and the center and rear wheels. This is carried out in a similar manner to the response of the axle differentials to the speed difference between the inner wheels and the outer wheels. The interaxle differential is equipped with a lockup clutch. The lockup clutch is activated by a floor mounted switch. The lockup clutch will neutralize normal interaxle differential operation and transfer drive to all three axles regardless of the ground conditions 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 three evenly spaced shafts (2). The shafts are used to support two planetary gear sets (3) and (13). Both planetary gear sets are in constant mesh with each other and each of the gears is free to rotate around shafts (2). Planetary gear set (3) is in constant mesh with sun gear (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) which is installed onto output shaft (8) for the output drive to the tractor. When the machine is moving in a straight direction with equal ground resistance at each wheel the differential housing (4), planetary gears (3) and planetary gears (13) rotate as a unit. When the machine is turning, the turning radius changes 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 slows down. If wheel spin occurs at the front of the machine, drive to the center axle and drive to the rear axle would be reduced to a degree that would stop the machine. In this event, engaging the interaxle differential lock would restore drive to all axles. The differential effect is cancelled by locking the differential housing to the output shafts.

When the operator engages the differential lock, oil pressure is transmitted by the solenoid and relief valve to rotating housing (7). The oil pressure inside rotating housing (7) acts on piston (6) which forces the piston against clutch pack (5). Hub (15) and differential housing (4) are then connected. Both planetary gear sets and both sun gears are locked in 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 allows clutch pack (5) to disengage. Differential housing (4) and hub (15) are disconnected and the interaxle differential effect is restored.


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

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Illustration 8 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

A differential is an arrangement of gears which enables one shaft to drive two shafts with equal torque. The differential also allows the two shafts to rotate at different speeds. The differential in an axle enables drive to be maintained to both wheels through separate axle shafts when the machine is turning. The wheel on the inside of the turn will travel a shorter distance than the wheel on the outside of the turn. This causes the wheel on the inside of the turn to slow down while the wheel on the outside of the turn speeds up.

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

In adverse ground conditions, one or more of the wheels may lose traction. The action of the differential will result in a loss of drive as the differential allows the torque to be transmitted along the path of least resistance, which will be the wheel that is slipping. The differential in each axle can be locked in adverse conditions. Locking the differential provides direct drive to all the wheels at the same speed regardless of the resistance due to traction.

14 Power Train Systems Operation Section A differential divides the power that is sent to the machine wheels. During a turn, the inside wheel turns at a slower rate than the outside wheel. The differential still sends the same amount of torque to each wheel. Each differential has a differential lock. The main component of the differential lock is the clutch pack. When the differential lock switches are engaged, the clutch pack connects one axle shaft to the differential case. Both axle shafts are connected in order to form a solid axle with no differential effect. The inside components of the differential receive lubrication from the oil that is inside the axle housing. Bevel pinion shaft (1) is in constant mesh with bevel gear (16). The bevel pinion shaft and the bevel gear provide a gear reduction and a change in the direction of drive by 90 . Differential case (11) is attached to bevel gear (16). The differential case holds spiders (12). Four pinion gears (13) are free to rotate around the spiders. Side gears (10) and (15) are mounted in the differential case. The side gears are meshed with the pinion gears. Axle shafts (9) and (14) are splined into the side gears. When the bevel gear (16) is turned by bevel pinion shaft (1), differential case (11) is also turned. If the resistance between each of the road wheels is equal, pinion gears (13) will not rotate around spiders (12). The pinion gears will turn with the spiders. The pinion gears will turn the side gears with equal speed and equal torque. When the machine is turning, the wheel that is on the inside of the turn will travel a shorter distance than the wheel on the outside of the turn. This causes the wheel on the inside of the turn to slow down while the wheel on the outside of the turn speeds up. The axle shaft on the inside of the turn and the side gears on the inside of the turn slow down. This causes the pinion gears to rotate on the spiders. The wheel, the axle shaft and the side gear on the inside will slow down as the machine turns. The wheel, the axle shaft and the side gear on the outside will speed up in proportion to the inside wheel. The differential between the speed of the two wheels is taken up by the rotation of the bevel gears around the spiders. Both wheels are driven with equal force, but at different speeds.

When one wheel has more traction than the other wheel, the torque travels by the path of least resistance to the wheel that has less traction. The wheel with less traction will spin and the wheel that has traction will be stationary. In this condition, the machine will lose drive. A differential lock is provided in order to prevent loss of drive in adverse conditions.

Differential Lock Operation The axle differential lock should be engaged when the machine is being operated on a loose surface or a soft surface. The axle differential lock should also be engaged if wheel spin is experienced and additional traction is required. Damage can occur to drive line components through a buildup of torsional stress, if operating the machine on a hard surface with the axle differential lock engaged. The machine should only be driven in a straight line when the axle 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 against pressure 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). Pinion gears (13) stop revolving and this causes side gear (15) and axle shaft (14) to lock. Both axle shafts now rotate at the same speed as the bevel gear and differential case.


Differential (Center Axle) SMCS Code: 3258-CE

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Illustration 9 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

A differential is an arrangement of gears which enables one shaft to drive two shafts with equal torque. The differential also allows the two shafts to rotate at different speeds. The differential in an axle enables drive to be maintained to both wheels through separate axle shafts when the machine is turning. The wheel on the inside of the turn will travel a shorter distance than the wheel on the outside of the turn. This causes the wheel on the inside of the turn to slow down while the wheel on the outside of the turn speeds up.

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

In adverse ground conditions, one or more of the wheels may lose traction. The action of the differential will result in a loss of drive as the differential allows the torque to be transmitted along the path of least resistance, which will be the wheel that is slipping. The differential in each axle can be locked in adverse conditions. Locking the differential provides direct drive to all the wheels at the same speed regardless of the resistance due to traction.

16 Power Train Systems Operation Section A differential divides the power that is sent to the machine wheels. During a turn, the inside wheel turns at a slower rate than the outside wheel. The differential still sends the same amount of torque to each wheel. Each differential has a differential lock. The main component of the differential lock is the clutch pack. When the differential lock switches are engaged, the clutch pack connects one axle shaft to the differential case. Both axle shafts are connected in order to form a solid axle with no differential effect. The inside components of the differential receive lubrication from the oil that is inside the axle housing. Bevel pinion shaft (1) is in constant mesh with bevel gear (17). The bevel pinion shaft and the bevel gear provide a gear reduction and a change in the direction of drive by 90 . Differential case (12) is attached to bevel gear (17). The differential case holds spiders (13). Four pinion gears (14) are free to rotate around the spiders. Side gears (11) and (16) are mounted in the differential case. The side gears are meshed with the pinion gears. Axle shafts (10) and (15) are splined into the side gears. When the bevel gear (17) is turned by bevel pinion shaft (1), differential case (12) is also turned. If the resistance between each of the road wheels is equal, pinion gears (14) will not rotate around spiders (13). The pinion gears will turn with the spiders. The pinion gears will turn the side gears with equal speed and equal torque.

When one wheel has more traction than the other wheel, the torque travels by the path of least resistance to the wheel that has less traction. The wheel with less traction will spin and the wheel that has traction will be stationary. In this condition, the machine will lose drive. A differential lock is provided in order to prevent loss of drive in adverse conditions.

Differential Lock Operation The axle differential lock should be engaged when the machine is being operated on a loose surface or a soft surface. The axle differential lock should also be engaged if wheel spin is experienced and additional traction is required. Damage can occur to drive line components through a buildup of torsional stress, if operating the machine on a hard surface with the axle differential lock engaged. The machine should only be driven in a straight line when the axle 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 against pressure 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). Pinion gears (14) stop revolving and this causes side gear (16) and axle shaft (15) to lock. Both axle shafts now rotate at the same speed as the bevel gear and differential case.

Center Axle Through Drive

When the machine is turning, the wheel that is on the inside of the turn will travel a shorter distance than the wheel on the outside of the turn. This causes the wheel on the inside of the turn to slow down while the wheel on the outside of the turn speeds up. The axle shaft on the inside of the turn and the side gears on the inside of the turn slow down. This causes the pinion gears to rotate on the spiders. The wheel, the axle shaft and the side gear on the inside will slow down as the machine turns. The wheel, the axle shaft and the side gear on the outside will speed up in proportion to the inside wheel. The differential between the speed of the two wheels is taken up by the rotation of the bevel gears around the spiders. Both wheels are driven with equal force, but at different speeds.

Illustration 10

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


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Illustration 11 (1) Bevel pinion shaft (2) Gear

(17) Bevel gear (19) Gear assembly

Drive is input to the axle from the drive shaft to gear assembly (19). Gear assembly (19) is meshed with gear (2) on bevel pinion shaft (1). This provides the drive to bevel gear (17). Drive to the rear axle is carried by gear assembly (19) to an output shaft that connects to the drive shaft to the rear axle via a universal joint.


Final Drive SMCS Code: 4050

Illustration 13

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Final Drive (Rear Axle)

Illustration 12 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)

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(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 is splined onto spindle (4). Spindle (4) is bolted to the axle 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 splined to axle shaft (5). Drive comes to sun gear (6) through axle shaft (5). Ring gear (2) is held stationary, so the planetary carrier is driven in the same direction as the sun gear at a reduced speed. The carrier is bolted to the 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 final drive and the axle.


Power Train Hydraulic System SMCS Code: 3000; 3100; 4000 The hydraulic system for the power train consists of two separate subsystems. The first system supplies oil to the torque converter and the planetary transmission. The second system supplies oil to the output transfer gear, the interaxle differential lock and the three axle differential locks.

Torque Converter and Transmission

Illustration 14

The transmission hydraulic control system provides pressurized oil to the clutches of the transmission planetary. , Pressurized oil is also supplied to the torque converter and to the torque converter lockup clutch. Oil from the sump (1) of the torque converter is drawn through suction screen (2) by oil pump (3).

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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 control valve (13). Downshift solenoid (5) and upshift solenoid (6) control the flow of pressurized oil to rotary actuator (7). Rotary actuator (7) determines the position of selector spool (12) in selector and pressure control valve (13).

20 Power Train Systems Operation Section Selector spool (12) in selector and pressure control valve (13) allows pilot oil to flow to individual valves (8) on pressure control valve (9). The position of the selector spool determines the path of the pilot oil to the individual valves. Each individual valve is a modulating valve which controls the pressure of the oil that is supplied to the clutches in the transmission planetary. Oil from the selector and pressure control valve also supplies the torque converter. The oil that is used by the torque converter is then sent through the transmission oil cooler and back to the transmission as lubricant.

Transmission Oil Pump and Suction Screen

Illustration 16

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(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 in the top of torque converter housing (16). The oil pump is splined to gear (17) which is driven by the input to the torque converter via idler gear (15). The oil is drawn by the oil pump from the sump in the torque converter housing. The oil then passes through suction screen (2) to port (14) in the oil pump. The oil is then pumped from port (19) to the system. Hose (18) receives oil from the system in order to lubricate the pump drive group.

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

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Transmission Oil Filter

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

Transmission Oil Cooler

Illustration 19

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This is a view from below the transmission oil cooler.

Illustration 17

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

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

Illustration 18

The oil cooler for the transmission is located on the right side of the engine below the oil cooler for the brake system.

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Location of transmission oil filter

The transmission oil filter is located on the right side of 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.


Output Transfer Gears and Differentials

Illustration 20

A second hydraulic circuit supplies lubrication for the output transfer gears. The circuit also controls the 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 remove any metallic particles that may be present in the oil. The charging and scavenging pump charges the output transfer gears and the differential locks. The charging and scavenging pump for the output transfer gears and the differential locks is mounted on the top of the flywheel housing to the left of the engine.

g00807200

The oil from the charging and scavenging pump is fed via filter (27) to solenoid and relief valve (28) that is mounted on the output transfer gear case. The solenoid and relief valve controls the lock for interaxle differential (29) and the locks for the axle differentials. The solenoid and relief valve also provides lubrication oil for the output transfer gear (30). Operation of the solenoid and relief valve applies oil pressure to the lockup clutch in the interaxle differential in order to engage the interaxle differential lock. Within the solenoid and relief valve, a second solenoid valve controls the axle differential locks (31) in the three axles. The circuit allows the axle differential locks to be engaged only when the interaxle differential lock is engaged.

23 Power Train Systems Operation Section Engagement of the axle differential locks is achieved when the solenoid valve allows pressurized oil from the solenoid and relief valve to fill the clutches on the differentials in each axle. When the axle differential lock is unselected, the oil in the clutches of the axle differentials is able to drain to the top of the output transfer gear case as additional lubrication. The oil enters the output transfer gear case at the top. The oil drains down to the sump of the output transfer gear case and the oil provides lubrication to the gears and the bearings. i01536341

Transmission Hydraulic Control SMCS Code: 3167

Illustration 21

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24 Power Train Systems Operation Section Control of the torque converter and the planetary transmission is achieved by a selector and pressure control valve that controls the supply of pressurized oil to the pressure control valve. The pressure control valve contains individual valves that control the oil pressure in each clutch and the oil pressure in the torque converter lockup clutch. Oil is supplied by pump (1) through oil filter (2). The pressurized oil is available to downshift solenoid (3), upshift solenoid (4) and torque converter lockup clutch solenoid (9). Pressurized oil is also supplied to selector and pressure control valve (13). Selector and pressure control valve (13) regulates the oil pressure. The selector and pressure control valve sends pressurized oil to pressure control valve (7) for clutch actuation. The selector and pressure control valve also provides the pilot signal to the individual valves (6) in the pressure control valve. The selector and pressure control valve also supplies oil to the torque converter. The maximum pressure of the oil to the torque converter is regulated by relief valve (11) in the selector and pressure control valve. Rotary actuator (5) is controlled by downshift solenoid (3) and upshift solenoid (4). The rotary actuator turns selector spool (10) in the selector and pressure control valve. The selector spool determines the path of the pilot oil to the individual valves. When the machine is in NEUTRAL, the downshift solenoid is selected. This ensures that the rotary actuator holds the selector spool in the correct position. The selector and pressure control valve includes a neutralizer valve. Neutralizer valve (12) prevents pressurized oil from being supplied to the selector spool unless the engine is started with the transmission control in the NEUTRAL position. When the operator selects drive, the ECM for the power train closes downshift solenoid (3) and opens upshift solenoid (4). The upshift solenoid supplies pressurized oil to the rotary actuator. This causes the rotary actuator to rotate. This turns the selector spool in the selector and pressure control valve. Pilot oil is directed by the selector spool to the individual valves for clutch 2 and clutch 6.

Solenoid valve (9) for the torque converter lockup clutch is closed. This allows torque converter drive as the machine accelerates. As the machine speed matches the engine speed, the ECM for the power train sends an electrical signal to the solenoid valve for the torque converter lockup clutch. This allows a pilot oil supply to the modulating valve (8) for the torque converter lockup clutch. This causes the torque converter lockup clutch to engage direct drive between the engine and the planetary transmission. The ECM reads the information from the engine output speed sensor and from the transmission output speed sensor. The ECM shifts the transmission at predetermined speeds. Table 2

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

i01545381

Power Train Electronic Control System SMCS Code: 4800 Control of the power train is achieved by electronically controlled hydraulic actuation. Control of the power train is maintained by the electronic control module. The electronic control module is also responsible for controlling the other systems that are used on the machine. The ECM receives inputs from different sensors and from operator requests. The ECM sends electronic signals in order to control transmission shifts and other power train components. The ECM receives the following inputs:

• Engine output speed


• 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 which include control of the secondary steering system and control of the hoist system. The ECM will also control default mode operation in the event of electrical failure. A service technician can use Caterpillar ET to communicate with the ECM. The service technician can interrogate the ECM for details of faults and the service technician can monitor operating conditions.


Power Train Electronic Control System

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Illustration 22 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

Seven hydraulically activated clutches in transmission (14) provide seven forward speeds and one reverse speed. Speed selections and direction selections are made manually by using transmission control (10). The power train electronic control system electronically controls the shifting of the transmission. In order for the transmission to be shifted to the desired speed and the desired direction, the ECM (5) receives the operator input from transmission control (10). The ECM sends a signal to downshift solenoid (7) or upshift solenoid (8). The downshift solenoid and the upshift solenoid turn the rotary actuator which turns the selector spool in the selector and pressure control valve. The modulating valves in the pressure control valve modulate the oil pressure of the clutches that are selected.

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

A modulating valve is also used to control oil pressure to the torque converter lockup clutch. Pilot oil is supplied to the modulating valve for the torque converter lockup clutch by torque converter lockup clutch solenoid (6). The torque converter lockup clutch provides direct drive between the engine and the transmission planetary. The power train ECM uses input signals from the following components to ensure correct engagement of the clutches: engine speed sensor (12) and transmission output speed sensors (15). The power train ECM also controls the following functions: interaxle differential lock, axle differential locks, hoist control, and secondary steering system.


Electronic Control Module

Sensors In The Power Train

The electronic control module (ECM) is located at the right rear side of the cab. The ECM controls the shifting of the transmission. The transmission control sends the operator input to the ECM. The operator input indicates the desired speed for the transmission and the desired direction for the transmission. The ECM makes decisions that are based on the input information and on the memory information. After the ECM receives the input information and the memory information, the ECM sends a corresponding response to the outputs. The inputs and the outputs are connected to the machine harness by two 40-pin connectors.

Sensors provide information to the power train electronic control module (ECM) about changing conditions. The sensor signal changes proportionally to the changing conditions. The following type of sensor signals are recognized by the power train ECM.

• Frequency signals: The frequency (Hz) of the

sensor signal varies as the condition changes.

Transmission Gear Sensor

Inputs The machine has several input devices. Input devices inform the ECM of the operating conditions of the machine. The machine has two types of inputs, switch inputs and sensor inputs. The switch inputs of the ECM are provided with the following signals from the switches: an open, a ground, and a +battery. Sensors provide a constantly changing signal to the ECM.

Outputs The ECM responds to decisions by sending electrical signals through the outputs. The outputs can create an action or the outputs can provide information to the ECM.

Input/Output The CAT Data Link is used to communicate with the other electronic control modules on the machine. The CAT Data Link is bidirectional. The CAT Data Link allows the sharing of information with other electronic controls.

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

• The ECM sends the following information to the

Caterpillar Monitoring System: engine speed, machine ground speed, parking brake switch status, transmission speed selection, and service code of the transmission.

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

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

Illustration 23

g00616555

Transmission Gear Sensor

The transmission gear sensor is an input to the Power Train ECM. The sensor tells the ECM the position of the rotary actuator and the selector spool. The sensor is connected mechanically to the rotary actuator of the transmission.


Speed Sensors (Engine Output and Transmission Output)

i01562748

Output Transfer Gears Lubrication System SMCS Code: 1300; 3159 The lubrication of the output transfer gears is achieved by a separate hydraulic system from the hydraulic system that serves the planetary transmission and the torque converter . The lubrication system for the output transfer gears also provides oil for the axle differential locks and for the interaxle differential lock that is located in the case for the output transfer gears.

Illustration 24

g00288428

Typical Speed Sensor

There are two transmission output speed sensors and one engine output speed sensor on the machine. The speed sensors are inputs of the ECM. These speed sensors are frequency sensors. Frequency sensors produce a signal (Hz) which varies as the condition changes. The sensor generates a sine wave signal from the gear teeth as the gear teeth pass the sensor. The sensor produces a signal that equals one pulse per gear tooth. This signal is sent to the ECM. The ECM measures the frequency of the signal in order to determine the speed of the condition. The ECM receives signals from the speed sensors. The ECM uses the input from the speed sensors in order to determine the speed of the system. The ECM uses the input from the speed sensors in order to regulate transmission shifts. Each speed sensor has two connections to the ECM (+ and − ). For all of the speed sensors, connector contact 2 is the signal line and connector contact 1 is the return line. Two transmission speed sensors measure transmission output speed in order to provide protection against failure.

Note: The speed sensors are used to diagnose each other during normal operation. The ECM periodically checks the value from the speed sensor. If an incorrect value is found, the ECM will log a service code that indicates a fault for a speed sensor circuit.

Charging and Scavenging Pump for the Output Transfer Gears and Differential Locks

Illustration 25

g00797836

Charging and scavenging pump for the output transfer gears and differential locks

Charging and scavenging pump (1) supplies oil for the lubrication of the output transfer gears. The charging and scavenging pump also supplies oil for the control of the interaxle differential lock and the axle differential locks. The charging and scavenging pump is driven from the engine flywheel via an idler gear.


Oil Filter for the Output Transfer Gears

A second solenoid controls the oil to the axle differential locks. The priority valve gives priority to the oil supply for the differential locks over the oil supply to the output transfer gears. The relief valve regulates the maximum pressure in the output transfer gears and the differential lock system. Oil from the solenoid and relief valve enters the case for the output transfer gears at the top. The oil is gravity fed to the output transfer gears.

Illustration 26

g00790144

Magnetic Screen for the Output Transfer Gears

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 of the machine. The base of the oil filter contains a bypass valve in order to allow the oil to continue to the output transfer gears in the event of a blockage in the oil filter. A switch notifies the operator in the event of a blockage in the oil filter.

Solenoid and Relief Valve Illustration 28

g00797837

Magnetic screen for the output transfer gears

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

Illustration 27

g00797846

Solenoid and relief valve

Oil from the oil filter is then fed to solenoid and relief valve (3) that is mounted on the case of the output transfer gears. The solenoid and relief valve provides oil to the output transfer gears and the differential locks. The solenoid and relief valve incorporates two solenoid valves, a priority valve and a relief valve. One solenoid in the solenoid and relief valve controls the oil to the interaxle differential lock and the oil to the solenoid valve for the axle differential locks.


Pressure Control Valve (Transmission) SMCS Code: 3074

Transmission Pressure Control Valve

Illustration 29

g00797930

31 Power Train Systems Operation Section Pressure control valve (1) has seven modulation reduction valves (2) for the transmission planetary and one modulation reduction valve (3) for the torque converter lockup clutch. There is one modulation reduction valve for each clutch in the transmission planetary. Each modulation reduction valve acts separately. This is known as Individual Clutch Modulation (ICM). The modulation reduction valves control the amount of pressure that will be used for clutch engagement and for the release of the clutch. The modulation reduction valves also determine the duration of clutch engagement. Each load piston body (4) has an identification letter for the purposes of disassembly and assembly. Pilot passages (5) are connected to passages from the rotary selector spool of the selector and pressure control valve. Pump oil from the selector and pressure control valve is in passage (6). Drain passages (7) are connected to the transmission case reservoir. All of the modulation reduction valves operate in a similar way, so only the basic operation is provided.

The Beginning of a Shift and the Clutch is Filling

Illustration 30

g00799039

32 Power Train Systems Operation Section When a shift is started, pilot passage (5) receives pilot oil at the correct sequence from the rotary selector spool. Selector piston (8) and load piston (9) move against the force of springs (10). Modulation reduction valve (11) moves against the force of spring (12). Passage (13) is blocked to drain passage (14). Passage (13) is open to passage (6). The pump oil now begins to fill the clutch. The pressure of the oil that is filling the clutch is balanced against the force of springs (10) as the springs are compressed by the selector piston. This is the primary pressure for the clutch. The primary pressure helps to fill the clutch smoothly in order to avoid harsh transmission shifts. As the oil flows to passage (13), oil is able to flow through load piston orifice (15) and passage (16).

Completed Shift with an Engaged Clutch

Illustration 31

g00799037

33 Power Train Systems Operation Section After the clutch is full of oil, the pressure of the pump oil in the selected clutch increases. The pressure of the oil that is flowing through the load piston orifice increases. This oil goes between selector piston (8) and load piston (9). The oil moves the load piston against springs (10). This further increases the compression of the springs. As the springs are compressed, the force of the springs is increased. The pressure of the oil in the clutch is balanced against the force of springs (10). This allows an increase in the oil pressure in the clutch. Clutch oil flows through an orifice in the modulation reduction valve (11). Ball check valve (17) opens and oil flows into the slug chamber at the left end of the modulation reduction valve. The pressure in the clutch is now at the maximum. Modulation reduction valve (11) moves to the right and to the left in order to maintain a constant pressure in passage (13). The amount of time that is necessary for the maximum pressure in the clutch to be reached is dependent on the size of load piston orifice (15) and the force of springs (10). The force of springs (10) can be adjusted by using shims in load piston (9).


Shift with a Released Clutch

Illustration 32

When a clutch is disengaged, pilot passage (5) is open in order to drain through the rotary selector spool. The force of springs (10) moves selector piston (8) fully to the right against load piston body (18). Passage (16) is now aligned with drain passage (19). The force of springs (10) moves load piston (9) fully to the right against selector piston (8). Modulation reduction valve (11) is moved fully to the 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) and the pressure in the clutch is released. Decay orifice (20) in drain passage (19) controls the amount of time that is necessary for the clutch pressure to release.

g00799065


Torque Converter Lockup Clutch

Illustration 33

The operation of the modulating valve for the torque converter lockup clutch is identical to the operation of the modulating valves for the clutches in the transmission planetary. Pilot oil is supplied by the transmission oil pump. The pilot oil is controlled by the torque converter lockup solenoid. The torque converter lockup solenoid is located alongside the downshift solenoid and the upshift solenoid. The modulating valve for the torque converter lockup clutch is mounted on the transmission pressure control valve. The Power Train Electronic Control Module (Power Train ECM) will energize the torque converter lockup clutch solenoid when direct drive is necessary. During direct drive, the engine is mechanically connected to the transmission by the activation of the lockup clutch. When direct drive is not necessary, the torque converter lockup clutch solenoid is deactivated. The pilot oil supply to the modulating valve for the torque converter lockup clutch is cut off. The machine will then be in torque converter drive. The engine will be hydraulically connected to the transmission.

Engaging the Lockup Clutch

g00799196

When the Power Train ECM activates the lockup clutch solenoid, pilot oil from the transmission pump is allowed to flow into pilot oil passage (21). As pilot oil flows into the pilot oil passage, selector piston (22) and load piston (23) are moved to the right against the force of spring (24). Drain passage (25) is blocked. Spring (24) pushes modulation reduction valve (26) against the force of spring (27). As modulation reduction valve (26) moves to the right, drain passage (28) is blocked, and pressurized oil is allowed to flow from passage (6) to passage (29) to the torque converter lockup clutch. Oil in passage (29) also flows through load piston orifice (30). This oil goes between selector piston (22) and load piston (23). This moves load piston (23) further to the right.

36 Power Train Systems Operation Section The pressure of the clutch oil in passage (29) increases after the clutch is full of oil. Some of the oil from passage (29) goes through orifice (31) in modulation reduction valve (26). This oil opens ball check valve (32). The oil then goes into slug chamber (33). This pressure helps the springs push both modulation reduction valve (26) and load piston (23) back to the left. The oil that is flowing through load piston orifice (30) is delivered at a fixed rate. While load piston (3) is controlled by the oil from load piston orifice (30), modulation reduction valve (26) moves up and down. This causes the pressure in the lockup clutch to increase gradually. This gradual increase due to the movement of the spool is called modulation. The modulation of modulation reduction valve (26) maintains a constant pressure in passage (29). When load piston (23) goes fully against the stop, modulation stops. The pressure in the lockup clutch is now at the maximum. The lockup clutch is fully engaged. The amount of time that is necessary for the maximum pressure in the lockup clutch to be reached is dependent on the size of load piston orifice (30) and the force of spring (24). The force of spring (24) can be adjusted by using shims in load piston (23).

Releasing the Lockup Clutch When pilot oil passage (21) does not receive pilot oil, the force of spring (24) moves selector piston (22) to the left against load piston body (34). This uncovers drain passage (25). Oil between selector piston (22) and load piston (23) drains through drain 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). Modulation reduction valve (26) moves up to the fullest extent as 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 torque converter sump.


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

Illustration 34

The selector and pressure control valve controls the flow of oil that goes to the pressure control valve. The selector and pressure control valve consists of five valves. The following chart provides the basic function of each valve.

g00800393


Neutralizer Valve

Table 3

Operation Of The Components In The Selector And Pressure Control Valve Valve

Function

Priority reduction valve (2)

This valve controls the pressure of the pilot oil that is available to rotary selector spool (4).

Neutralizer valve (3)

When the transmission is not in NEUTRAL and the engine is started, this valve stops the flow of pilot oil to rotary selector spool (4).

Rotary selector spool (4)

The rotary selector spool sends pilot oil to the appropriate transmission clutches.

Relief valve (12)

This valve controls the maximum pressure in the transmission hydraulic system.

Torque converter inlet relief valve (11)

This valve controls the maximum inlet oil pressure to the torque converter.

Priority Reduction Valve At the selector and pressure control valve, the oil from the transmission oil pump flows to several locations. The oil flows through passage (1) to priority reduction valve (2). The oil flows through an orifice in the priority reduction valve. This oil opens a check valve. The oil then flows to the upper end of priority reduction valve (2). As the oil pressure increases, the priority reduction valve is moved downward against the force of the spring. The pressure of the oil that is flowing from priority reduction valve (2) to neutralizer valve (3) is controlled by the priority reduction valve. As priority reduction valve (2) moves downward, pump oil in passage (1) is able to flow through through passage (13). Some of this oil flows to relief valve (12). Relief valve (12) controls the maximum pressure in passages (1), (13), and (8). Some of the oil from passage (13) flows through passage (8) to the pressure control valve. This oil is used to fill the clutches in the transmission. Some of the oil from passage (13) also flows to rotary selector spool (4). This oil activates neutralizer valve (3). When the rotary selector spool is in the NEUTRAL position, oil is able to flow to chamber (14). This causes neutralizer valve (3) to move downward. When neutralizer valve (3) is moved downward, the oil 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 the movement of the selector pistons in the pressure control valve.

Neutralizer valve (3) will not allow movement of the machine if the engine is started and rotary selector spool (4) is not in the NEUTRAL position. When the engine is started and the transmission is in NEUTRAL, pressure oil from passage (13) flows to rotary selector spool (4). The pressure oil then flows to chamber (14). The pressure in chamber (14) moves neutralizer valve (3) downward against the force of the spring. This allows pilot oil to go around the neutralizer valve to chamber (5) of the rotary selector spool. The clutches can be engaged in the transmission. As neutralizer valve (3) moves downward, pilot oil is able to flow through an orifice in the neutralizer valve to the upper end of the neutralizer valve. Neutralizer valve (3) is now held in the open position by the pressure of the pilot oil. When rotary selector spool (4) is moved from the NEUTRAL position, pressure oil from passage (13) cannot go to chamber (14). Chamber (14) is now open to chamber (6) because of the position of rotary selector spool (4). When the machine is not in NEUTRAL and the engine is started, the position of rotary selector spool (4) stops the flow of pump oil to chamber (14). Neutralizer valve (3) will not move downward in order to provide oil to chamber (5). No oil can flow to 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 selector pistons in the pressure control valve that receive pilot oil and the selector pistons that are drained. Orifices in the spool provide the correct sequence in order for the clutches to engage. A rotary actuator is mechanically connected to the upper end of the rotary selector spool. The rotary actuator is hydraulically controlled by the upshift solenoid and the downshift solenoid. The rotary actuator turns rotary selector spool (4). The transmission gear switch is also connected to the upper end of the spool. The transmission gear switch communicates with 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 springs provide detent positions in order to hold the spool in each selected speed position.

39 Power Train Systems Operation Section Chamber (5) of rotary selector spool (4) contains pilot oil. The position of the spool will send this pilot oil through a passage to the pressure control valve. The oil flows to a selector piston. This causes the selector piston to move. This will cause a clutch to engage in the transmission. Chamber (5) has a screen which stops foreign material from entering the pressure control valve. The clutches of the transmission that are disengaged return any pressure oil that is in the selector pistons to chamber (6). Chamber (6) allows the 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 move neutralizer valve (3). In the other speed positions, chamber (14) is blocked from pump oil and open to chamber (6).

Relief Valve Relief valve (12) controls the maximum pressure in the transmission hydraulic system. Pump oil comes from passage (13) to relief valve (12). The oil flows through an orifice in the relief valve. This opens a poppet valve. Oil fills the chamber between the poppet and the slug. As the pressure increases, the oil moves relief valve (12) upward against the force of the spring. When the pressure of the oil reaches the relief pressure, relief valve (12) allows oil to flow through passage (10) to the torque converter. The pressure setting of relief valve (12) can be changed by the removal or the addition of shims inside the spool of the relief valve.

Torque Converter Inlet Relief Valve Torque converter inlet relief valve (11) controls the maximum oil pressure that is going into the torque converter. Oil that flows past relief valve (12) will then flow to the torque converter. If the pressure of the oil reaches the relief pressure, torque converter inlet relief valve (11) will open. The oil will flow to the transmission case reservoir until the pressure is reduced to less than the maximum pressure that is required for the torque converter.


Rotary Actuator (Transmission) SMCS Code: 3166

Illustration 35

The rotary actuator is controlled by downshift solenoid (1) and upshift solenoid (2). Pressure oil from either solenoid flows into chamber (3). The pressure oil presses against stationary vane (12) and against rotary vane (14) of rotor (15). This pressure oil causes the rotor to turn. Rotor (15) is mechanically connected to the rotary selector spool. The rotary selector spool is part of the selector and pressure control valve. Rotor (15) turns the rotary selector spool. During an upshift, pressure oil from the upshift solenoid flows through passage (9). This causes upshift valve (10) to move to the left. Drain passage (11) is now closed by the upshift valve. The pressure oil flows into upshift valve (10). This moves ball (8) to the left and oil flows into chamber (13) between stationary vane (12) and rotary vane (14). This causes rotor (15) to turn in a clockwise direction.

g00802458

The oil that is in chamber (3) on the opposite side of 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) pushes downshift valve (4) to the right until the valve opens drain passage (5). The oil that is in chamber (3) is now able to drain. When the rotary selector spool and rotor (15) achieve the correct speed position, the transmission gear switch that is connected to the rotary selector spool sends an electrical signal to the Power Train Electronic Control Module (Power Train ECM). The Power Train ECM closes the upshift solenoid. This stops the flow of pressure oil in passage (9). The movement of rotor (15) then stops. During a downshift, pressure oil from the downshift solenoid flows through passage (6). Downshift valve (4) is moved to the left. This closes drain passage (5). The pressure oil from passage (6) goes into downshift valve (4). The pressure oil moves ball (7) to the left and oil flows into chamber (3). This causes rotor (15) to turn in a counterclockwise direction.

41 Power Train Systems Operation Section The oil that is in chamber (13) presses against upshift valve (10). This causes ball (8) to move to the 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 drain passage (11) is open to chamber (13). When the rotor achieves the correct speed position, the Power Train ECM deactivates the downshift solenoid. 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. The downshift solenoid is always activated in the NEUTRAL position so that the rotor is locked in position.

42 Power Train Testing and Adjusting Section

Testing and Adjusting Section

5. Install the steering frame lock. Refer to Operation and Maintenance Manual, SEBU7498. 6. Place blocks in front of the wheels and behind the wheels.

Troubleshooting

7. Make sure that all oil pressure is released before any fittings, hoses or components are worked on. i01526102

Machine Preparation for Troubleshooting SMCS Code: 3000-035

When testing and adjusting the transmission and power train, move the machine to an area clear of obstructions, with safe exhaust ventilation for the exhausts. Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before testing and adjusting the transmission and power train. 1. Move the machine to a smooth horizontal location. Move away from any machines that are working and any personnel.

8. Push on the brake pedal many times until there is no brake oil pressure. Visual checks are the first steps in order to troubleshoot a problem. The visual checks find the problems that can be quickly corrected. If the visual checks do not show any problems, the operational checks are the next steps. The operational checks permit the identification of possible problems with the machine during operation. i01556822

General Troubleshooting Information SMCS Code: 3000-035 When you are attempting to define a problem with the power train, it is necessary to perform the procedures that are contained in this section. A visual inspection of the system must be carried out in order to eliminate many of the less complex problems. Upon completion of a visual inspection, if the cause of the problem has not been diagnosed, carry out operational checks of the system.

Illustration 36

g00792760

Dump body prop

2. Raise the dump body of the truck. Install the dump body prop in order to support the dump body. 3. Ensure that the transmission control is in the NEUTRAL position. Move the parking brake control to the ENGAGED position and stop the engine. 4. Permit only one operator on the machine. Either keep other personnel away from the machine, or keep other personnel in the sight of the operator.

If both visual inspection and operational checks have been carried out and there is still no clear indication of the cause of the problem then it will be necessary to refer to the troubleshooting procedures and the test procedures that are contained in this manual. Troubleshooting a system such as the power train is a complex operation. Refer to the various troubleshooting sections in this manual for specific routines for troubleshooting.

43 Power Train Testing and Adjusting Section This list of possible problems and possible corrections will only provide an indication of the location of a problem and the repairs that are required. It is important to remember that a problem is not necessarily caused by a single part, but by the relation of one part to a number of other parts. This information cannot provide all the possible problems and corrections. It is necessary for service personnel to define the problem. Any repairs may then be carried out. i01526104

Visual Inspection SMCS Code: 3000-035 Perform a visual inspection at the beginning of troubleshooting a problem. Ensure that the transmission control is in the NEUTRAL position. Move the parking brake control to the ENGAGED position and stop the engine.

Do not check for leaks with your hands. Pin hole (very small) leaks can result in a high velocity oil stream that will be invisible close to the hose. This oil can penetrate the skin and cause personal injury. Use cardboard or paper to locate pin hole leaks. 1. Check the oil levels for the various components of the power train. Check the oil level for the torque converter and the transmission. Refer to Operation and Maintenance Manual, SEBU7498, “Torque Converter and Transmission Oil Level - Check”. Check the oil level for the transfer gear. Refer to Operation and Maintenance Manual, SEBU7498, “Transfer Gear Oil Level - Check”. Check the oil levels for the differentials and final drives. Refer to Operation and Maintenance Manual, SEBU7498, “Differential and Final Drive Oil Level - Check”.

2. Check the level of the coolant in the engine cooling system. Refer to Operation and Maintenance Manual, SEBU7498, “Cooling System Level - Check”. Note: Engine coolant passes through the oil cooler for the transmission in order to cool the torque converter and the transmission oil. 3. Check for leaks.

Inspect all oil lines, hoses, and connections for damage or for leaks. Look for oil on the ground under the machine.

Note: If oil can leak out of a fitting or a connection, air can leak into the system. Air in the system can be as bad as a low oil level. 4. Check the electrical system. Inspect the harnesses and the electrical connectors for the ECM. Refer to Electrical Schematic, RENR5136. With the engine start switch and the battery disconnect switch in the OFF position, check the 20 ampere fuse for the Electronic Control Module. If the fuse is open, replace the fuse. Refer to Operation and Maintenance Manual, SEBU7498, “Fuses - Replace”. Inspect the electrical harnesses for damaged wires or for broken wires. Disconnect each connector and look for pins and sockets that have been bent, broken, or removed. Look for any foreign material inside the connectors. The connectors must be tightened with normal force. The connectors must be disconnected with the same amount of force. Check the Electronic Control Module. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR3442, “Power Train Electronic Control System”.

5. Check the batteries. Turn the battery disconnect switch to the ON position and check the condition of the batteries.

6. Check the filters and the screens. Inspect the suction screen for the torque converter and the transmission. Clean the suction screen for the torque converter and the transmission. Refer to Operation and Maintenance Manual, SEBU7498, “Torque Converter Scavenge Screen - Clean”. Inspect the oil filter for the torque converter and the transmission. Refer to Operation and Maintenance Manual, SEBU7498, “Torque Converter and Transmission Oil Filter - Replace” in order to remove the oil filter. Refer to Operation and Maintenance Manual, SEBU7498, “Oil Filter - Inspect” in order to inspect the oil filter.

44 Power Train Testing and Adjusting Section Note: The oil filter for the torque converter and the transmission has a bypass valve which allows oil to bypass the oil filter elements when the inlet pressure to the oil filter rises due to a blockage in the oil filter. Any oil that does not go through the filter elements goes directly into the hydraulic circuit. Dirty oil causes restrictions in valve orifices, sticking valves, etc. Inspect the oil filter for the transfer gear. Refer to Operation and Maintenance Manual, SEBU7498, “Transfer Gear Oil Filter - Replace” in order to remove the oil filter. Refer to Operation and Maintenance Manual, SEBU7498, “Oil Filter Inspect” in order to inspect the oil filter.

Note: The oil filter for the transfer gear has a bypass valve which allows oil to bypass the oil filter elements when the inlet pressure to the oil filter rises due to a blockage in the oil filter. Any oil that does not go through the filter elements goes directly into the hydraulic circuit. Dirty oil causes restrictions in valve orifices, sticking valves, etc. The oil filter for the transfer gear incorporates a switch, which illuminates an indicator in the cab. This indicator alerts the operator of a restriction in the oil filter for the transfer gear. Inspect the magnetic screen for the torque converter and the transmission. Refer to Operation and Maintenance Manual, SEBU7498, “Torque Converter Scavange Screen - Clean”. The magnetic screen for the torque converter and the transmission is located within the suction screen for the torque converter and the transmission. 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 the nonferrous particles. This is a list of some of the particles that may be found in the filter elements:

• Aluminum particles give the indication of torque converter failure or sleeve bearing failure.

• Bronze particles give the indication of sleeve bearing failure.

• Rubber particles give the indication of rubber seal or hose failure.

• Shiny steel particles give the indication of pump failure.

• Iron chips, steel chips or plastic particles

give the indication of broken components in transmission or transfer gears.

If any contamination is found in the filter elements or the screens, all the components of the transmission hydraulic system must be cleaned. Do not use any damaged parts. Any damaged parts must be removed and new Caterpillar parts must be installed. i01556743

Operational Checks SMCS Code: 3000-035 Operate the machine in each direction and in all speeds. Operate the interaxle differential and operate the axle differentials. Check that the power train is operating correctly in all functions. If the power train is not operating correctly refer to the troubleshooting information that is contained in this manual. Use the troubleshooting information in order to investigate the problem. The checks for troubleshooting that are included in this manual are designed to guide service personnel in a correct troubleshooting procedure. The checks and procedures are set in sequence in order to find problems and causes quickly. The checks for troubleshooting should be carried out in order. Do not proceed to the next check until the current check has been carried out fully. If the correct result for the check is found, go directly to the next check. Take note of all warnings and notices in these checks. You must read all the warnings and the notices before you start a check. Before carrying out a procedure, it is important to read the procedure thoroughly. The checks that follow can be used to find many of the problems that may occur during the operation of the machine. The checks that follow can also give an indication of the part of the system that has the problem.

45 Power Train Testing and Adjusting Section i01545887

Torque Converter Troubleshooting SMCS Code: 3101-035 Note: The troubleshooting information is intended to aid in diagnosing a given problem. The possible causes are ordered from the most probable cause to the least probable cause. The possible causes should be examined in order until the problem is resolved. Refer to Systems Operation, Testing and Adjusting, “Machine Preparation for Troubleshooting” before you perform any testing and adjusting or troubleshooting. Prior to carrying out troubleshooting on the torque converter, use Caterpillar ET in order to diagnose any fault codes that may be present. Refer to Systems Operation, Troubleshooting,Testing and Adjusting , RENR3442, “Power Train Electronic Control System”. If fault codes are present, repair the cause of the fault code.

The Torque Converter or the Transmission is Overheating Possible Cause 1. The machine may have been operated incorrectly.

• Operate the machine in the correct manner.

Refer to Operation and Maintenance Manual, SEBU7498.

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

• Check the engine coolant level. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”. 3. The power train oil level is lower than the specification.

• Check the power train oil level. Refer to

Systems Operation, Testing and Adjusting, “Visual Inspection”.

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

• Refer to Systems Operation, Testing and

Adjusting, RENR5126, “Hoist, Steering, Suspension, and Fan Drive Systems” for further information regarding the fan drive system.


Adjusting, RENR1362 for more information on the engines for the 740.

5. There is debris and damaged components in the power train.

• Inspect the oil filter for debris. • Determine the origin of the debris and repair the damaged component.

• Change the oil in the power train and install a new oil filter.

6. The coolant flow through the transmission oil cooler is below the specification. 7. The oil flow through the transmission oil cooler is below the specification.

• Check the oil pressure to the transmission oil cooler. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”.

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

• Check the inlet relief pressure for the torque

converter. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”.

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

9. The torque converter is worn or damaged.

• Inspect the components of the torque converter for wear or damage. Refer to Disassembly and Assembly, RENR5139, “Torque Converter Disassemble and Assemble”.

10. The torque converter lockup clutch is not functioning correctly.

• Test the function of the torque converter lockup clutch. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”.

The Torque Converter Lockup Clutch Does Not Engage Possible Cause 1. There may be an electrical fault between the ECM for the power train and the solenoid for the torque converter lockup clutch.


• Check the wiring and check the connectors for damage. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”.

• Repair any damage that is found in the wiring

harness or replace any loose connections that are found.

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




• Inspect the oil filter for debris. • Determine the origin of the debris and repair the damaged component.


4. The pressure of the oil in the transmission hydraulic control system may not be within the specification.

• Test the pressures of the oil in the transmission hydraulic hydraulic control control system. Make any necessary repairs or adjustments. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control - Test and Adjust”.

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

• Check the operation of the solenoid for the torque converter lockup clutch before the engine start switch is turned off. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control - Test and Adjust”.

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

• Check the operation of the modulating

valve for the torque converter lockup clutch. Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control System - Test and Adjust”.

7. Components in the torque converter lockup clutch may be worn.

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

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

The Torque Converter Lockup Clutch Clutch Does Not Disengage Disengage and the Engine Dies at Low Speed Possible Cause 1. There may be an electrical fault between the ECM for the power train and the solenoid for the torque converter lockup clutch.





• Inspect the oil filter for debris. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”.

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


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

• Check the operation of the solenoid for the torque converter lockup clutch before the engine start switch is turned off. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control - Test and Adjust”.

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

• Check the operation of the modulating

valve for the torque converter lockup clutch. Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control System - Test and Adjust”.

47 Power Train Testing esting and Adjusting Adjusting Section Section 5. The piston in the torque converter lockup clutch may be sticking.

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

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

i01554329

Transmission Planetary Troubleshooting SMCS Code: 3160-035 Note: The troubleshooting information is given to aid in diagnosing a given problem. problem. The possible possible causes are ordered from the most probable cause to the least probable cause. The possible causes should be examined in order until the problem is resolved. Refer to Systems Operation, Testing and Adjusting, “Machine “Machine Preparatio Preparation n for Troublesho roubleshooting” oting” before you perform any testing and adjusting or troubleshooting. Prior to carrying out troubleshooting on the transmission planetary group, use Caterpillar ET in order to diagnose any fault codes that may 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 transmission control for correct • Test

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

2. The power train oil level is lower than the specification.




• Test the pressures of the oil in the transmission hydraulic control system. Make any necessary repairs or adjustments. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”.

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

• Test the individual valves for the transmission

clutches. clutches. Refer to Systems Systems Operation, Operation, Testing and Adjusting, “Transmission Hydraulic Control - Test and Adjust”.

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

• Test the pilot pressure for the transmission

hydraulic control system and test the clutch pressures. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control - Test and Adjust”. If the clutch pressures are low and the pilot pressure is normal, remove the selector spool from the selector and pressure pressure control valve and inspect inspect the selector selector spool for blockages.

6. The neutralizer valve in the selector and pressure control valve may be preventing the machine from engaging a gear.

• The selector spool was not in the NEUTRAL

position when the engine was started. Move the transmission control to the NEUTRAL position and stop the engine. Restart the engine and attempt to engage a forward gear.

• Test the correct function of the neutralizer

valve. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control Test and Adjust”.

7. The wiring harness for the power train may be damaged.




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

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

48 Power Train Testing and Adjusting Section 9. There is debris and damaged components in the power train.


• Determine the origin of the debris and repair the damaged components. • Change the oil in the power train and install a new oil filter. 10. There may be a mechanical failure of another major component in the power train.

• Check the power train components for

• Allow the oil in the transmission to warm up fully.

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

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

7. The power train oil level is lower than the specification.



8. The service brakes may not be released fully.

damage.

• Check the correct operation of the service

The Transmission Stays in One Gear or The Transmission Will Not Shift Correctly Possible Cause 1. The wiring harness for the power train may be damaged. The wiring to the upshift solenoid or the downshift solenoid may be damaged.




2. The transmission hold switch may be engaged.

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

3. The high gear limit for the transmission may have been selected.

• Check if a high gear limit has been selected.

Refer to Operation and Maintenance Manual, SEBU7498, SEBU7498, “Changing “Changing Speed and Direction”. Direction”.

4. The transmission control lever may not be in the FLOAT position.

• Move the transmission control lever to the FLOAT position.

5. The transmission oil may be cold.

• Check the temperature of the transmission oil.

brakes. Refer to Systems Operation, Testing and Adjusting, RENR5139, “Braking System”.

9. The transmission output speed sensors may be faulty.

• Check the connections on the transmission output speed sensors. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”.

• Test the transmission output speed sensors.

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

10. The transmission may be operating in an elevated shift point mode.

• Check the correct function of the ECM and the

inputs to the ECM. Refer to Systems Operation, Testing and Adjusting, RENR3442, “Power Train Electronic Control System”.



12. One or more of the individual valves for the transmission clutches may not be functioning correctly.


• Test the function of the individual valves

for the transmission clutches. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control - Test and Adjust”.

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

• Inspect the individual valves and clear any blockages in the decay orifices.

14. The drain orifice in the end of the selector spool in the transmission hydraulic control may be blocked.

• Inspect the selector spool and clear any blockages in the selector spool.



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


16. The seals on the piston in the transmission clutch may be leaking.

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

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

• Inspect the oil for debris. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”.

• Inspect the clutches for damage. Refer to

Disassembly and Assembly, RENR5138, “Transmission Planetary - Disassemble and Assemble”.

• Check that the disks and the plates are within

the specified dimensions. Refer to Disassembly and Assembly, RENR5138, “Transmission Planetary - Disassemble and Assemble”.

• Check the springs in the clutches. Refer to

Service Manual, RENR5133, “Power Train Specifications” for the correct specifications for the springs in the transmission clutches.

18. The torque converter lockup clutch may not be operating and there may be insufficient ground speed for a transmission shift.

• Test the operation of the torque converter

lockup clutch. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control - Test and Adjust”.

The Transmission Slips In One Gear Possible Cause 1. The power train oil level is lower than the specification.



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

• Test the individual valves. Refer to

Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control System - Test and Adjust”.

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

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

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













The Transmission Is Overheating Possible Cause 1. The power train oil level is outside the specifications.



2. The machine may have been operated incorrectly.

• Operate the machine in the correct manner.

Refer to Operation and Maintenance Manual, SEBU7498.

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

• Check the engine coolant level. Refer to


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


Adjusting, RENR5136, “Hoist, Steering, Suspension, and Fan Drive Systems” for further information regarding the fan drive system.

• Refer to Systems Operation, Testing and Adjusting, RENR1363.

5. The coolant flow through the transmission oil cooler is below the specification. 6. The oil flow through the transmission oil cooler is below the specification.

• Check the oil pressure to the transmission oil cooler. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”.

7. The torque converter inlet pressure is outside specifications.

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

• Replace the torque converter inlet relief

valve. Refer to Disassembly and Assembly, RENR5138, “Power Train”.

8. The torque converter outlet pressure is outside specifications.

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



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


10. The torque converter lockup clutch may not be functioning correctly.

• Test the correct function of the torque converter lockup clutch. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control - Test and Adjust”.

The Transmission Does Not Shift Smoothly Possible Cause 1. The power train oil level is lower than the specification.



2. The primary pressures for the transmission clutches may be incorrect.

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

• Adjust the primary pressures for the

transmission clutches if the primary pressures are incorrect.







5. The torque converter lockup clutch may still be engaged during shifts.

• Check the correct operation of the

torque converter lockup clutch. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control”.

6. The transmission may be operating in an elevated shift point mode.

• Check the correct function of the ECM and the

inputs to the ECM. Refer to Systems Operation, Testing and Adjusting, RENR3442, “Power Train Electronic Control System”.

7. There may be a fault with the controlled throttle shifting function.

• Investigate the correct functioning of the

controlled throttle shifting. Refer to Systems Operation, Testing and Adjusting, RENR3442, “Power Train Electronic Control System”.

The Transmission Hesitates During Shifting Possible Cause 1. One or more individual valves for the transmission clutches may not be functioning correctly.

• Test the individual valves for the transmission

clutches. Refer to Systems Operation, Testing and Adjusting, “Transmission Hydraulic Control - Test and Adjust”.







4. The power train oil level is outside the specification.



5. The seals on the piston in the transmission clutch may be leaking.

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









7. The torque converter lockup clutch may not engage correctly after a shift.


• Check the correct operation of the torque converter lockup clutch.

• Inspect the torque converter lockup clutch for

damage. Refer to Disassembly and Assembly, RENR5138, “Torque Converter - Disassemble and Assemble”. i01528148

Interaxle Differential Troubleshooting

• Check the circuit. If there is a blown fuse,

replace the blown fuse. Refer to Operation and Maintenance Manual, SEBU7498, “Fuses - Replace” and Schematic, RENR5136, “Electrical Systems”. If there is damage to the wiring harness, repair the damage. If there is a faulty switch, replace the faulty switch.

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

• Test the oil supply to the solenoid and relief valve . Refer to Systems Operation, Testing and Adjusting, “Interaxle Differential - Test”.

SMCS Code: 3287-035 Note: The troubleshooting information is intended to aid in diagnosing a given problem. The possible causes are ordered from the most probable cause to the least probable cause. The possible causes should be examined in order until the problem is resolved. Refer to Systems Operation, Testing and Adjusting, “Machine Preparation for Troubleshooting” before you perform any testing and adjusting or troubleshooting. Prior to carrying out troubleshooting on the interaxle differential lock, use Caterpillar ET in order to diagnose any fault codes that may be present. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR3442, “Power Train Electronic Control System”. If fault codes are present, repair the source of the fault code.

4. The solenoid that controls the interaxle differential in the solenoid and relief valve is not functioning correctly.

• Test the solenoid for correct operation. Refer

to Systems Operation, Testing and Adjusting, “Interaxle Differential - Test”.

5. The seals on the piston in the interaxle differential may be leaking.

• The pressure of the oil in the interaxle

differential may be lower than the specification. Check the pressure of the oil when the interaxle differential is engaged. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”.

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

• Inspect the oil filter and inspect the magnetic screen for debris.

The Interaxle Differential Does Not Engage

• Determine the origin of the debris and repair

Possible Causes

• Change the oil. Clean the magnetic screen

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

• Inspect the condition of the lines. Refer to


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

or replace the damaged component. and install a new Caterpillar oil filter.

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

• Inspect the condition of the disks and plates

in the interaxle differential. Replace the disks and the plates if the disks and the plates are worn or damaged. Refer to Disassembly and Assembly, RENR5139, “Power Train”.

The Interaxle Differential Does Not Disengage A failure of the interaxle differential can cause wind up in the power train. This may be noticeable as an increase in the effort of steering.

53 Power Train Testing and Adjusting Section Possible Causes 1. The solenoid that controls the interaxle differential in the solenoid and relief valve may be sticking.

All Three Axle Differentials Will Not Lock When The Axle Differential Locks Are Engaged

• Check the operation of the solenoid. Refer

Possible Causes

• Check the pressure of the oil for the interaxle

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

to Systems Operation, Testing and Adjusting, “Interaxle Differetial - Test”. differential when the interaxle differential is unselected. Refer to Systems Operation, Testing and Adjusting, “Interaxle Differential - Test”.

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

• Inspect the oil filter and inspect the magnetic screen for debris.

• Determine the origin of the debris and repair or replace the damaged component.

• Check the circuit. If there is a blown fuse,

replace the blown fuse. Refer to Operation and Maintenance Manual, SEBU7498, “Fuses - Replace” and Schematic, RENR5136, “Electrical Systems”. If there is damage to the wiring harness, repair the damage. If there is a faulty switch, replace the faulty switch.

2. The oil supply to the solenoid and relief valve that is located on the output transfer gears may not be sufficient.

• Test the oil supply to the solenoid and relief

• Change the oil. Clean the magnetic screen and install an new Caterpillar oil filter. 3. The piston in the interaxle differential may be sticking.

valve. Refer to Systems Operation, Testing and Adjusting, “Interaxle Differential - Test”.

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

• Test the solenoid for the interaxle differential

• Check the oil pressure in the interaxle

differential when the interaxle differential is unselected. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures ”. If the oil pressure is normal, the piston may be sticking. Inspect the lockup clutch for correct operation. Refer to Disassembly and Assembly, RENR5139, “Power Train”. i01528161

Differential Troubleshooting SMCS Code: 3258-035 Note: The troubleshooting information is intended to aid in diagnosing a given problem. The possible causes are ordered from the most probable cause to the least probable cause. The possible causes should be examined in order until the problem is resolved. Refer to Systems Operation, Testing and Adjusting, “Machine Preparation for Troubleshooting” before you perform any testing and adjusting or troubleshooting. Prior to carrying out troubleshooting on the axle differential locks, use Caterpillar ET in order to diagnose any fault codes that may be present. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR3442, “Power Train Electronic Control System”.

lock in the solenoid and relief valve for correct operation. Refer to Systems Operation, Testing and Adjusting, “Interaxle Differential - Test”.

4. The solenoid for the axle differential locks in the solenoid and relief valve is not functioning correctly.

• Test the solenoid for correct operation. Refer

to Systems Operation, Testing and Adjusting, “Differential - Test”.

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

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

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

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

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


• Inspect the condition of the disks and plates

in the differential. Replace the disks and the plates if the disks and the plates are damaged or worn. Refer to Disassembly and Assembly, RENR5139, “Power Train”.

The Axle Differential On One Or More Axles Will Not Lock When The Differential Lock Switch Is Engaged Possible Causes 1. There may be leaks in the oil lines to the differential.

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

• Visually inspect the lines to the output transfer gears. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”.

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

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

• Visually inspect the lines to the output transfer gears. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”.

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

• Inspect the condition of the disks and the

plates in the differential. Replace the disks and the plates if the disks and the plates are worn or damaged. Refer to Disassembly and Assembly, RENR5139, “Power Train”.

4. An axle shaft may be damaged or broken.

• Check the condition of the axle shaft on

the axle that will not lock. Replace the axle shaft if the axle shaft is not within the specification. Refer to Disassembly and Assembly, RENR5139, “Power Train”.


Testing and Adjusting

Torque Converter Pressures i01579055

Power Train Pressures

Testing the Pilot Pressure for the Torque Converter Lockup Clutch 1. Ensure that the engine is stopped and that the parking brake control is in the ENGAGED position.

SMCS Code: 3000-PX

Personal injury or death can result from sudden machine movement.

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

Sudden movement of the machine can cause injury to persons on or near the machine. Prevent possible injury by performing the procedure that follows before working on the machine. NOTICE Do not connect or disconnect hose fittings to or from the quick disconnect nipples when there is pressure in the system. This will prevent damage to the seals that are in the fitting. Illustration 37

Refer to Systems Operation, Testing and Adjusting, “Machine Preparation For Troubleshooting” before you perform any testing and adjusting or troubleshooting. Before you carry out any testing, ensure that you have read the procedure and that you have understood the procedure.

g00805203

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

Note: Make sure that the filters and the screens are clean before you test any pressures. Make sure that the oil is at operating temperature before you perform these tests. Table 4

Required Tools Part Number

Description

Qty

1U-5481

Pressure Gauge Group

1

1U-5482

Pressure Adapter Group

1

8T-5200

Generator and Counter Signal Group

1

Illustration 38

FT-2796

Connector Harness

1

4. Disconnect the wiring harness from upshift solenoid (2), downshift solenoid (3) and torque converter lockup clutch solenoid (4).

It will be necessary to raise the cab in order to gain access to the various pressure test points for the power train. The guards beneath the engine and the transmission may require lowering.

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5. Connect the wiring harness from the downshift solenoid to the torque converter lockup clutch solenoid. 6. Lower the cab. Take care to ensure that the hose assembly is not trapped when the cab is lowered.

56 Power Train Testing and Adjusting Section 7. Ensure that the transmission control is in the NEUTRAL position and that the parking brake is engaged. Press and hold the service brake pedal. 8. Start the engine and run the engine at low idle. 9. Observe the pressure gauge. With the oil at normal operating temperature, the pilot oil pressure for the torque converter lockup clutch must be within the values that are shown in Table 7. 10. Stop the engine and raise the cab. Remove the fitting and the hose from test point (1) and replace the plug. 11. Reconnect the wiring harness correctly to the upshift solenoid, the downshift solenoid and the torque converter lockup clutch solenoid.

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Illustration 40

5. Remove the small cover from the transmission cover.

Testing the Initial Pressure for the Torque Converter Lockup Clutch The pressure in the torque converter lockup clutch can be measured at test point (D) on the transmission pressure control valve.

1. Ensure that the engine is stopped and that the parking brake control is in the ENGAGED position. 2. Raise the cab. Refer to Operation and Maintenance Manual, SEBU7498, “Cab - Tilt”.

6V-6064 Transmission

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

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Illustration 41 Test Cover

6. Install the 6V-6064 Transmission Test Cover in the place of the small cover. Use four bolts to hold the test cover in position. 7. Replace the transmission cover on the top of the transmission. Use four bolts to hold the test cover in position.

Illustration 39

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Modulating Valve for the Torque Converter Lockup Clutch

4. Remove load piston plug (5). Note: Care must be taken in order to ensure that the plug is not dropped into the transmission.

Illustration 42

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57 Power Train Testing and Adjusting Section 8. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group to test point (D). Use a suitable 90 fitting. Attach the opposite end of the hose assembly to the 4000 kPa (580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group.

Illustration 44

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18. Remove the 6V-6064 Transmission Test Cover from the transmission cover and install the small cover to the transmission cover. Illustration 43

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19. Replace the transmission cover.

9. Disconnect the wiring harness from downshift solenoid (2), upshift solenoid (3) and torque converter lockup clutch solenoid (4).

20. Reconnect the wiring harness correctly to the upshift solenoid, the downshift solenoid and the torque converter lockup clutch solenoid.

10. Connect the wiring harness for the downshift solenoid to the torque converter lockup clutch solenoid.

Testing the Torque Converter Lockup Clutch Pressure

11. Lower the cab. Take care to ensure that the hose assembly is not trapped when the cab is lowered. 12. Ensure that the transmission control is in the NEUTRAL position and that the parking brake is engaged. Press the service brake pedal and hold the service brake pedal. 13. Start the engine and run the engine at low idle.

The pressure in the torque converter lockup clutch can be measured at test point (D) on the transmission pressure control valve.

1. Ensure that the engine is stopped and that the parking brake control is in the ENGAGED position. 2. Raise the cab. Refer to Operation and Maintenance Manual, SEBU7498, “Cab - Tilt”.

14. Observe the pressure gauge. With the oil at normal operating temperature, the initial oil pressure for the torque converter lockup clutch must be within the values that are shown in Table 7. 15. Stop the engine and raise the cab. Remove the fitting and the hose from test point (D). 16. Remove the transmission cover with the 6V-6064 Transmission Test Cover from the top of the transmission. 17. Replace load piston plug (5).

Illustration 45

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

58 Power Train Testing and Adjusting Section 6. Disconnect the wiring harness from downshift solenoid (2), upshift solenoid (2) and torque converter lockup clutch solenoid (4). 7. Connect the wiring harness for the downshift solenoid to the torque converter lockup clutch solenoid. 8. Lower the cab. Take care to ensure that the hose assembly is not trapped when the cab is lowered.

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Illustration 46 6V-6064 Transmission

9. Ensure that the transmission control is in the NEUTRAL position and that the parking brake is engaged. Press the service brake pedal and hold the service brake pedal.

Test Cover

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

10. Start the engine and run the engine at low idle. 11. Observe the pressure gauge. With the oil at normal operating temperature, the maximum oil pressure for the torque converter lockup clutch must be within the values that are shown in Table 7. 12. Stop the engine and raise the cab. Remove the fitting and the hose from test point (D). 13. Remove the 6V-6064 Transmission Test Cover. 14. Replace the small cover on the top of the transmission.

Illustration 47

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5. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group to test point (D) on the pressure control valve. Use a suitable 90 fitting. Attach the opposite end of the hose assembly to the 0 to 4000 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group.

15. Reconnect the wiring harness correctly to the upshift solenoid, the downshift solenoid and the torque converter lockup clutch solenoid.

Inlet Relief Pressure for the Torque Converter

Illustration 49

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The relief pressure of the torque converter inlet can be measured at test point (6). Test point (6) is located on the left side of the transmission. Illustration 48

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59 Power Train Testing and Adjusting Section 1. Ensure that the engine is stopped and that the parking brake control is in the ENGAGED position.

Testing the Pressure for the Transmission Oil Pump

2. Raise the cab. Refer to Operation and Maintenance Manual, SEBU7498, “Cab - Tilt”. 3. Disconnect the fitting (6). Install a suitable swivel tee between fitting (6) and the line to the transmission pump drive housing. Install the correct fitting and the correct hose assembly from the 1U-5482 Pressure Adapter Group to the swivel tee. Attach the opposite end of the hose assembly to the 0 to 4000 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. 4. Lower the cab. Take care to ensure that the hose assembly is not trapped when the cab is lowered. 5. Ensure that the transmission control is in the NEUTRAL position and that the parking brake is engaged. Press and hold the service brake pedal. 6. Start the engine and operate the engine at low idle. Observe the pressure gauge. With the oil at normal operating temperature, the main relief pressure must be within the values that are shown in Table 7. 7. Operate the engine at high idle. Observe the pressure gauge. With the oil at normal operating temperature, the torque converter inlet pressure must be within the values in Table 7. 8. Stop the engine and raise the cab. Remove the fitting and the hose from the swivel tee and remove the swivel tee from fitting (6). Reconnect the line to fitting (6).

Pressures For The Transmission Hydraulic Control System

Illustration 51

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

1. Ensure that the engine is stopped and that the parking brake control is in the ENGAGED position. 2. Raise the cab. Refer to Operation and Maintenance Manual, SEBU7498, “Cab - Tilt”. 3. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on test point (7). Attach the opposite end of the hose assembly to the 0 to 4000 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. 4. Lower the cab. Take care to ensure that the hose assembly is not trapped when the cab is lowered. 5. Start the engine and operate the engine at low idle. Observe the pressure gauge. With the oil at normal operating temperature, the relief pressure for the transmission hydraulic control must be within the values that are shown in Table 7. 6. Operate the engine at high idle. Observe the pressure gauge. With the oil at normal operating temperature, the relief pressure for the transmission hydraulic control must be within the values that are shown in Table 7. 7. Stop the engine and raise the cab. Remove the hose from test point (7).

Illustration 50

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Testing the Pilot Pressure for the Transmission Hydraulic Control System

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Illustration 52

Test Cover

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

1. Ensure that the engine is stopped and that the parking brake control is in the ENGAGED position. 2. Raise the cab. Refer to Operation and Maintenance Manual, SEBU7498, “Cab - Tilt”. 3. Remove the transmission cover from the top of the transmission.

5. Install the 6V-6064 Transmission Test Cover to the transmission cover in the place of the small cover. Use four bolts to hold the test cover in position. 6. Remove the plug from test point (8). Install the correct fitting and the correct hose assembly from the 1U-5482 Pressure Adapter Group on test point (8). 7. Feed the hose through an opening in the 6V-6064 Transmission Test Cover. To prevent the spraying of oil, use a piece of plastic or use a piece of paper with the cover. Attach the opposite end of the hose assembly to the 0 to 4000 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. 8. Replace the transmission cover on the top of the transmission. 9. Lower the cab. Take care to ensure that the hose assembly is not trapped when the cab is lowered. 10. Ensure that the transmission control is in the NEUTRAL position and that the parking brake is engaged. Press the service brake pedal and hold the service brake pedal.

Illustration 53

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11. Start the engine and run the engine at low idle. 4. Remove the small cover from the transmission cover.

12. Observe the pressure gauge. With the oil at normal operating temperature, the pilot oil pressure for the transmission hydraulic control system must be within the values that are shown in Table 7. 13. Stop the engine and raise the cab. 14. Remove the transmission cover with the 6V-6064 Transmission Test Cover from the top of the transmission.

61 Power Train Testing and Adjusting Section 15. Remove the fitting and the hose from test point (8) and replace the plug.

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Illustration 57 Illustration 55

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5. Remove the small cover from the transmission cover.

16. Remove the 6V-6064 Transmission Test Cover from the transmission cover and install the small cover to the transmission cover. 17. Replace the transmission cover.

Testing the Initial Pressures for the Individual Transmission Clutches 1. Ensure that the engine is stopped and that the parking brake control is in the ENGAGED position. 2. Raise the cab. Refer to Operation and Maintenance Manual, SEBU7498, “Cab - Tilt”.

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Test Cover


Illustration 56

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3. Remove the transmission cover from the top of the transmission. 4. Remove seven load piston plugs (9) from the individual valves. Note: Ensure that the plugs are not dropped into the transmission.

62 Power Train Testing and Adjusting Section 16. Observe the pressure gauges for the transmission clutches that are used in NEUTRAL. Refer to Tables 5 and 6. With the oil at normal operating temperature, the primary pressure for the oil in the transmission clutches must be within the values that are shown in Table 8. 17. Decrease the engine speed to low idle. 18. Move the transmission control to the DRIVE position. 19. Increase the engine speed to high idle. Illustration 59

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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-4144 Coupler and 8T-0855 Pressure Gauge to test points (A), (B), (C), (E), (F), (G), and (H). 8. Disconnect the drive shaft to the front axle from the output yoke of the output transfer gear. Refer to Disassembly and Assembly, RENR5139, “Power Train”. Retract the drive shaft away from the output yoke and secure the drive shaft. 9. Disconnect the drive shaft between the output transfer gear and the hitch from the output yoke of the output transfer gear. Refer to Disassembly and Assembly, RENR5139, “Power Train”. Retract the drive shaft away from the output yoke and secure the drive shaft. 10. Remove the wiring harness from the two transmission output speed sensors. Connect a 8T-5200 Signal Generator to the speed sensors. Use a FT-2796 Connector Harness.

20. Observe the gauges for the transmission clutch that is used in FIRST gear. Refer to Tables 5 and 6. With the oil at normal operating temperature, the initial pressure for the oil in the transmission clutch must be within the values that are shown in Table 8. 21. Decrease the engine speed to low idle. 22. Start the signal generator. Refer to Special Instruction, SEHS8579, “Use of 8T-5200 Signal Generator / Counter Group”. 23. Increase the frequency of the signal from the signal generator until the transmission shifts from first gear to second gear. 24. Increase the engine speed to high idle. 25. Observe the gauges for the transmission clutches that are used in SECOND gear. Refer to Tables 5 and 6. With the oil at normal operating temperature, the initial pressure for the oil in the transmission clutches must be within the values that are shown in Table 8. 26. Decrease the engine speed to low idle. 27. Increase the frequency of the signal from the signal generator and observe the initial pressures for each transmission gear.

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

28. Once the transmission is in SEVENTH gear and the pressures have been obtained for each clutch, reduce the frequency of the signal from the signal generator until the output is zero.

12. Lower the cab. Ensure that the hoses to the gauges and the connector harness is not trapped.

29. Move the transmission control to the REVERSE position. Increase the engine speed to high idle and observe the clutch pressures.

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

30. Decrease the engine speed to low idle.

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

31. Move the transmission control to the NEUTRAL position and stop the engine.

15. Increase the engine speed to high idle.

63 Power Train Testing and Adjusting Section 32. Compare the actual initial pressures that were recorded with the pressures that are provided in Table 8. 33. After the pressures are recorded, remove the test equipment and remove the transmission cover from the top of the transmission. 34. Replace load piston plugs (9).

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Test Cover


Illustration 60

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35. Remove the 6V-6064 Transmission Test Cover from the transmission cover and install the small cover to the transmission cover. 36. Replace the transmission cover. 37. Replace the drive shafts to the machine. Refer to Disassembly and Assembly, RENR5139, “Power Train”.

Testing the Maximum Pressures for the Transmission Clutches 1. Raise the cab. Refer to Operation and Maintenance Manual, SEBU7498, “Cab - Tilt”.

Illustration 63

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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-4144 Coupler and 8T-0855 Pressure Gauge to test points (A), (B), (C), (E), (F), (G), and (H).

Illustration 61

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2. Remove the small cover from the large cover.

64 Power Train Testing and Adjusting Section 16. Increase the engine speed to high idle. 17. Observe the gauges for the transmission clutch that is used in FIRST gear. Refer to Tables 5 and 6. With the oil at normal operating temperature, the maximum pressure for the oil in the transmission clutch must be within the values that are shown in Table 9. 18. Decrease the engine speed to low idle. 19. Start the signal generator. Refer to Special Instruction, SEHS8579, “Use of 8T-5200 Signal Generator / Counter Group”. Illustration 64

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5. Disconnect the wiring harness from torque converter lockup clutch solenoid (4). Note: This will allow the testing of transmission clutch pressures in torque converter drive without disconnecting the drive shaft from the transmission planetary. 6. Remove the wiring harness from the two transmission output speed sensors. Connect a 8T-5200 Signal Generator to the speed sensors. Use a FT-2796 Connector Harness. 7. Route the FT-2796 Connector Harness so that the signal generator can be mounted in the cab. 8. Lower the cab. Ensure that the hoses to the gauges and the connector harness is not trapped. 9. Ensure that the parking brake control is in the ENGAGED. 10. Start the engine and run the engine at low idle. 11. Increase the engine speed to high idle. 12. Observe the pressure gauges for the transmission clutches that are used in NEUTRAL. Refer to Tables 5 and 6. With the oil at normal operating temperature, the maximum pressure for the oil in the transmission clutches must be within the values that are shown in Table 9. 13. Decrease the engine speed to low idle. 14. Press and hold the service brakes. 15. Move the transmission control to the DRIVE position. Note: The engine will be turning against the torque converter, so there may be some small movement and vibration of the machine.

20. Increase the frequency of the signal from the signal generator until the transmission shifts from first gear to second gear. 21. Increase the engine speed to high idle. 22. Observe the gauges for the transmission clutches that are used in SECOND gear. Refer to Tables 5 and 6. With the oil at normal operating temperature, the maximum pressure for the oil in the transmission clutches must be within the values that are shown in Table 9. 23. Decrease the engine speed to low idle. 24. Increase the frequency of the signal from the signal generator and observe the maximum pressures for each transmission gear at high idle. 25. Once the transmission is in SEVENTH gear and the pressures have been obtained for each clutch, reduce the frequency of the signal from the signal generator until the output is zero. 26. Move the transmission control to the REVERSE position. 27. Increase the engine speed to high idle and observe the clutch pressures. 28. Decrease the engine speed to low idle. 29. Move the transmission control to the NEUTRAL position and stop the engine. 30. Compare the actual clutch pressures that were recorded with the pressures that are provided in Table 9. 31. After the pressures are recorded, remove the test equipment.


Illustration 65

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Illustration 67

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32. Remove the 6V-6064 Transmission Test Cover from the transmission cover and install the small cover to the transmission cover.

4. Disconnect the wiring harness from downshift solenoid (2), upshift solenoid (3) and torque converter lockup clutch solenoid (4).

33. Reconnect the wiring harness to the torque converter lockup clutch solenoid.

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

Testing the Upshift Pressure

6. Lower the cab and start the engine. Ensure that the parking brake is engaged. 7. Press and hold the service brakes. 8. Start the engine and operate the engine at low idle. The transmission will upshift through the gears to SEVENTH gear. 9. Observe the pressure gauge. With the oil at normal operating temperature, the pressure of the upshift oil must be within the values that are shown in Table 7. Illustration 66

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

1. Raise the cab. Refer to Operation and Maintenance Manual, SEBU7498, “Cab - Tilt”. 2. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on test point (10). Attach the opposite end of the hose assembly to the 0 to 1000 kPa (0 to 145 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. 3. Ensure that the transmission shift lever is in the NEUTRAL position.

10. Stop the engine and raise the cab. 11. Reconnect the wiring harness correctly to the upshift solenoid, the downshift solenoid and the torque converter lockup clutch solenoid. 12. Remove the hose and the gauges from test point (10).


Testing the Downshift Pressure

The pressure of the lubrication oil for the transmission planetary can be measured at test point (12).

1. Raise the cab. Refer to Operation and Maintenance Manual, SEBU7498, “Cab - Tilt”. 2. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on test point (12). Attach the opposite end of the hose assembly to the 0 to 400 kPa (0 to 58 psi) pressure gauge in the 1U-5481 Pressure Gauge Group.

Illustration 68

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

3. Lower the cab. Take care to ensure that the hose assembly is not trapped when the cab is lowered. 4. Start the engine.


5. With the transmission in NEUTRAL, run the engine at low idle. Record the pressure that is displayed on the gauge.

2. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on test point (11). Attach the opposite end of the hose assembly to the 0 to 1000 kPa (0 to 145 psi) pressure gauge in the 1U-5481 Pressure Gauge Group.

6. Run the engine at high idle and record the pressure that is displayed on the gauge. With the oil at normal operating temperature, the pressure for the lubrication oil for the transmission planetary must be within the values that are shown in Table 7.

3. Start the engine and operate the engine at low idle. Observe the pressure gauge. With the oil at normal operating temperature, the pressure of the downshift oil must be within the values that are shown in Table 7.

7. Stop the engine. 8. Raise the cab and remove the hose from test point (12).

Output Transfer Gears and Differential Lock Pressures

4. Stop the engine and raise the cab. 5. Remove the hose and the gauges from test point (11).

Testing the Transmission Lubrication Pressure

Illustration 70

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

Illustration 69

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

67 Power Train Testing and Adjusting Section Note: The pressure for the differential locks can also be measured at test point (13). Ensure that the interaxle differential lock and the axle differential locks are not selected. This may cause damage to the gauge that is used to measure the pressure of the oil.

Front Axle Differential

1. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on test point (13). Attach the opposite end of the hose assembly to the 0 to 1000 kPa (0 to 145 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. 2. Start the engine and operate the engine at low idle. Observe the pressure gauge. With the oil at normal operating temperature, the pressure of the lubrication oil for the transfer gears must be within the values that are shown in Table 7. 3. Operate the engine at high idle. Observe the pressure gauge. With the oil at normal operating temperature, the pressure of the lubrication oil for the transfer gears must be within the values in Table 7.

Illustration 71

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Line for the differential locks on the trailer

1. Disconnect line (14) to the rear axles and insert 6V-9508 Face Seal Plug into the line. Plug the line in order to prevent contamination of the oil.

Shut off the engine. The clutch pressure for the interaxle differential lock can be measured at test point (13).

1. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on test point (13). Attach the opposite end of the hose assembly to the 0 to 4000 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. Illustration 72

2. Start the engine and operate the engine at low idle. Select the interaxle differential lock. Refer to Operation and Maintenance Manual, “Differential Lock Control”. Observe the pressure gauge. With the oil at normal operating temperature, the pressure of the oil in the lockup clutch of the interaxle differential must be within the values in Table 7. 3. Select the axle differential locks. Refer to Operation and Maintenance Manual, “Differential Lock Control”. Observe the pressure gauge. With the oil at normal operating temperature, the pressure of the oil in the lockup clutches of the axle differentials must be within the values in Table 7.

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Line for the front axle differential lock

2. Disconnect line (15) from the elbow in the front axle. Insert 8T-8902 Tee between the line and the elbow in the front axle. 3. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on the 8T-8902 Tee. Attach the opposite end of the hose assembly to the 0 to 4000 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. 4. Start the engine and run the engine at low idle. 5. Select the interaxle differential lock and select the axle differential lock.

Shut off the engine. The pressures in the individual axle differentials can be measured.

6. Observe the pressure gauge. With the oil at normal operating temperature, the oil pressure in the clutch for the front axle differential must be within the values that are shown in Table 7. Shut off the engine.


Center Axle Differential

Illustration 75 Illustration 73

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Line for the center axle differential lock

Line for the front axle differential lock

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

3. Disconnect line (17) from the elbow in the center axle and insert 8T-8902 Tee between the line and the elbow in the front axle. 4. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on the 8T-8902 Tee. Attach the opposite end of the hose assembly to the 0 to 4000 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. 5. Start the engine and run the engine at low idle. 6. Select the interaxle differential lock and select the axle differential lock.

Illustration 74

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Line for the rear axle differential lock

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

7. Observe the pressure gauge. With the oil at normal operating temperature, the oil pressure in the clutch for the center axle differential must be within the values that are shown in Table 7. Shut off the engine.

Rear Axle Differential Lock

Illustration 76 Line for the front axle differential lock

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69 Power Train Testing and Adjusting Section 1. Disconnect line (15) from the elbow in the front axle and insert 6V-9508 Face Seal Plug into the line. Plug the fitting on the front axle in order to prevent contamination of the oil.

7. Observe the pressure gauge. With the oil at normal operating temperature, the oil pressure in the clutch for the rear axle differential must be within the values that are shown in Table 7. Shut off the engine.

Specifications For The Oil Pressures In The Power Train Table 5

SPEED SELECTION

Illustration 77

SPEED

ENGAGED CLUTCHES

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

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Line for the center axle differential lock

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

Table 6

Individual Valves for Transmission Clutches

Illustration 78

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Line for the rear axle differential lock

3. Disconnect line (16) from the elbow in the rear axle and insert 8T-8902 Tee between the line and the elbow in the front axle. 4. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on the 8T-8902 Tee. Attach the opposite end of the hose assembly to the 0 to 4000 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. 5. Start the engine and run the engine at low idle. 6. Select the interaxle differential lock and select the axle differential lock.

Clutch

Station

1

B

2

C

3

A

4

F

5

E

6

G

7

H

70 Power Train Testing and Adjusting Section Table 7

Test Point

Description

Specified Value

1

Pilot Pressure for the Torque Converter Lockup Clutch

1655 ± 138 kPa (240 ± 20 psi)

D

Primary Pressure For The Torque Converter Lockup Clutch

965 ± 35 kPa (140 ± 5 psi)

D

Pressure For The Torque Converter Lockup Clutch

2345 ± 70 kPa (340 ± 10 psi)

6

Relief Pressure for The Torque Converter Inlet (High Idle)

530 ± 35 kPa (77 ± 5 psi)

6

Relief Pressure For The Torque Converter Inlet (Low Idle)

115 ± 20 kPa (17 ± 3 psi)

7

Relief Pressure For The Transmission Hydraulic Control (High Idle)

3100 ± 70 kPa (450 ± 10 psi)

7

Relief Pressure For The Transmission Hydraulic Control (Low Idle)

2725 ± 70 kPa (395 ± 10 psi)

8

Pilot Pressure For The Transmission Hydraulic 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 Lubrication and Differential Locks

240 ± 105 kPa (35 ± 15 psi)

13

Interaxle Differential Gear and Differential Locks

2755 ± 345 kPa (400 ± 50 psi)

14,15, 16,17

Axle Differential Locks

2755 ± 345 kPa (400 ± 50 psi)

71 Power Train Testing esting and Adjusting Adjusting Section Section Table 8

Initial Initial Clutch Clutch Pressure Pressure (1) Station(1)

Clutch

Speed Position

“B”

“C”

No. 3

No. 1

Engaged Pr Pressure Clutches

“E “E”

“F”

“G”

“H”

No. 2

No. 5

No. 4

No. 6

No. 7

Pressure

Pressure

Pressure

Pressure

Pressure

Pressure

0

0

0

0

0

0

0

0

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

0

N

1

0

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

R

3 and 7

517 + 50 100 kPa kPa (75 + 7 - 15 psi)

0

0

0

0

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

0

0

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

0

0

0

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

0

0

0

0

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

0

0

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

0

0

0

0

0

0

1

2 and 6

2

1 and 6

0

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

3

3 and 6

517 + 50 100 kPa kPa (75 + 7 - 15 psi)

0

1 and 5

0

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

3 and 5

517 + 50 100 kPa kPa (75 + 7 - 15 psi)

0

0

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

0

0

380 + 50 - 100 kPa (55 ± 7 psi)

0

0

0

0

380 + 50 - 100 kPa (55 ± 7 psi)

0

0

4

5

(1)

“A”

6

1 and 4

0

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

7

3 and 4

517 + 50 100 kPa kPa (75 + 7 - 15 psi)

0

Station “D” is not used.


Maximum Maximum Clutch Clutch Pressure Pressure “A”

“B”

“C”

“E “ E”

“F”

“G”

“H”

Clutch

No. 3

No. 1

No. 2

No. 5

No. 4

No. 6

No. 7

Engaged Clutches

Pressure

Pressure

Pressure

Pressure

Pressure

Pressure

Pressure

0

2895 + 240 100 kPa (420 + 35 - 15 psi)

1

0

0

0

0

0

1760 + 240 - 100 kPa (255 + 35 15 psi)

3 and 7

0

0

0

0

0

2930 2930 ± 280 kPa (425± (425± 40psi) 40psi)

0

0

1980 + 240 - 100 kPa (287 + 35 15 psi)

0

0

2930 + 240 100 kPa (425 + 35 - 15 psi)

0

1 and 6

0

2895 + 240 100 kPa (420 + 35 - 15 psi)

0

0

0

2930 + 240 100 kPa (425 + 35 - 15 psi)

0

3 and 6

1760 + 240 - 100 kPa (255 + 35 15 psi)

0

0

0

0

2930 + 240 100 kPa (425 + 35 - 15 psi)

0

1 and 5

0

2895 + 240 100 kPa (420 + 35 - 15 psi)

0

1970 + 240 - 100 kPa (286 + 35 15 psi)

0

0

0

3 and 5

1760 + 240 - 100 kPa (255 + 35 15 psi)

0

0

1970 + 240 - 100 kPa (286 + 35 15 psi)

0

0

0

1 and 4

0

2895 + 240 100 kPa (420 + 35 - 15 psi)

0

1450 + 240 - 100 kPa (210 + 35 15 psi)

0

0

3 and 4

1760 + 240 - 100 kPa (255 + 35 15 psi)

0

1450 + 240 - 100 kPa (210 + 35 15 psi)

0

0

(1) Station(1)

Speed Position

N

R

1

2

3

4

5

6

7 (1)

2 and 6

Station “D” is not used.

0

0

0

73 Power Train Testing esting and Adjusting Adjusting Section Section i01545903

Transmission Hydraulic Control - Test and Adjust SMCS Code: 3073-025; 3073-081

Transmission Hydraulic Control System Main Relief Pressure Oil is supplied by the transmission oil pump that is mounted on the torque converter housing. The oil from the pump passes through the transmission oil filter that is mounted on the right side of the engine. The pressure of the oil that is supplied by the transmission transmission oil pump is controlled controlled by the main relief relief valve that is located in the transmission selector and pressure control valve. Test the pressure of the oil from the transmission oil pump. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. If the pressure of the oil from the transmission oil pump is lower than the specification at both low idle and at high idle, there may be a failure of the transmission oil pump. Alternatively, there may be damage to one or more of the seals in the transmission clutches. Test the individual clutches. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. The transmission oil pump cannot be serviced. It is necessary to replace the transmission oil pump. If the pressure of the oil from the transmission oil pump is too low at low idle but correct at high idle, the setting of the relief valve may be too low.

g00804541

Illustration 79

Adjustment of relief valve (1) is achieved by the addition or removal of spacers (2). The addition of spacers will increase the setting of the relief valve. The removal of spacers will decrease the setting of the relief valve. Refer to Table 10 for the correct selection of spacers. Table 10 (1) Chart of Spacers for Adjustment of the Relief Valve (1)

Spacer 145-0105

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

Spacer 145-0106

Spacer 145-0107

Spacer (1)

Thickness

Change Change in Pressure

0.25 0.25 mm (0.010 inch)

41 kPa (6.0 psi)

0.90 0.90 mm (0.035 inch)

145 kPa kPa (21.0 psi)

1.60 1.60 mm (0.063 inch)

261 kPa kPa (37.9 psi)

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


Pilot Pressure for the Transmission Hydraulic Control Valve

Table 11

Chart of Spacers for the Adjustment of the Priority Reduction Valve (1) Thickness

Change in Pressure

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)

Spacer

(1)

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

Testing the Function of the Neutralizer Valve The neutralizer valve prevents the transmission from selecting a gear if the engine is started and the selector spool is not in the NEUTRAL position. The following procedure may be used to test the function 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 the NEUTRAL position. Illustration 80

g00804588

The pilot pressure for the transmission hydraulic control valve is determined by priority reduction valve (3).

3. Disconnect the wiring harness from the upshift and downshift solenoids and from the torque converter lockup clutch solenoid.

Test the pilot pressure for the transmission hydraulic control. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. If the pressure is lower than the specification, the setting of the priority reduction valve is too low. If the pressure is higher than the specification, the setting of the priority reduction valve is too high. Adjustment of priority reduction valve (3) is achieved by the addition or removal of spacers (4). The addition of spacers will increase the setting of the relief valve. The removal of spacers will decrease the setting of the relief valve. Refer to table 10 for the correct selection of spacers.

Illustration 81

g00810209

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

75 Power Train Testing and Adjusting Section 5. Use a 9S-1721 Extension (1/4 inch square drive) and a 9U-6635 Reversible Ratchet to turn the transmission rotary selector spool. When the ratchet is fully turned in a clockwise direction, the rotary selector spool is in the NEUTRAL position. The order of the detent positions is NEUTRAL, REVERSE, REVERSE 1, and FIRST speed through SEVENTH speed.

Torque Converter Inlet Relief Pressure Testing and Adjusting

Note: Detent position REVERSE is not used in this application. Note: There is approximately 30 degrees of rotation between each detent of the rotary selector spool. 6. Rotate the selector spool to the FIRST speed position. 7. Lower the cab and start the engine. Ensure that the service brakes are engaged. 8. Correct operation of the neutralizer valve will prevent the engagement of the clutches for FIRST speed regardless of the position of the selector spool. 9. Stop the engine and raise the cab. 10. Return the selector spool to the NEUTRAL position and replace the wiring harness to the upshift and downshift solenoids and from the torque converter lockup clutch solenoid. 11. Replace the plug for the selector spool.

Torque Converter The Torque converter is supplied with oil on two levels. The torque converter is supplied with oil in order to allow the transfer of power through the torque converter. A separate circuit exists for the control of the lockup function of the torque converter in order to provide direct drive from the engine to the transmission.

Illustration 82

g00808310

The oil for the torque converter is supplied by the transmission selector and pressure control valve. The pressure of this oil is regulated by the torque converter 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 pressure for the torque converter is incorrect , bench test the torque converter inlet relief valve. If the setting of the torque converter inlet relief valve is incorrect, 5M-9622 Shims can be added or removed from behind the spring in the relief valve. If the setting of the torque converter inlet relief valve is correct, but the pressure of the oil in the torque converter is lower than the specification, there may be an incorrect supply of oil to the torque converter inlet relief valve. Test the setting of the main relief valve for the transmission hydraulic control system. If the supply of oil to the torque converter inlet relief valve is satisfactory, there may be a problem with the torque converter that allows oil to be lost. Remove the torque converter from the machine and investigate possible damage. Refer to Disassembly and Assembly, RENR5139, “Power Train”.


Torque Converter Lockup Clutch The torque converter lockup clutch is controlled by a modulating valve that is mounted on the pressure control valve for the transmission. The correct pressure for the torque converter lockup clutch is dependent upon the correct adjustment and the correct operation of the modulating valve for the torque converter lockup clutch.

7. If the solenoid does not appear to function, disconnect the connector for the solenoid valve. Check the resistance of the windings of the coil in the solenoid. The resistance of the windings in the solenoid should be 32.6 ± 1.6 . If the resistance of the windings is outside the specifications replace the solenoid.

The modulating valve for the torque converter lockup clutch is controlled by a pilot oil supply that is controlled by the torque converter lockup clutch solenoid.

If the solenoid coil is energized, the problem may lie with the solenoid cartridge. The problem could be a bent solenoid stem, a spring that is weak or broken, or a screen that is dirty or plugged.

To test the function of the solenoid valve for the torque converter lockup clutch, test the pressure of the pilot oil from the solenoid valve. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. If the pressure of the pilot oil from the torque converter lockup clutch solenoid is outside the specifications, there may be a fault with the supply of oil to the solenoid.

If the torque converter lockup clutch solenoid is functioning correctly and the pilot oil supply to the modulating valve is correct, there is a problem with the modulating valve for the torque converter lockup clutch.

Measure the main relief pressure for the transmission hydraulic control.

The following tests are required in order to determine the correct function of the modulating valve for the torque converter lockup clutch:

If the main relief pressure for the transmission hydraulic control is correct, there is a problem with the torque converter lockup clutch solenoid.

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

• Maximum pressure in the torque converter lockup clutch

Testing the Torque Converter Lockup Clutch Solenoid

• Initial pressure in the torque converter lockup

1. Ensure that the machine is parked on a level surface and that the parking brake control is engaged.

• Correct Pressure decay in the clutch

2. Move the key start switch to the ON position. Do not start the engine. 3. Raise the cab. 4. Disconnect the wires from the upshift solenoid, the downshift solenoid and the torque converter lockup clutch solenoid. 5. Connect the harness from the downshift solenoid to the torque converter lockup clutch solenoid. 6. Use a tag wire to check that the solenoid coil is energized. If the tag wire is attracted to the solenoid coil, this indicates that the solenoid coil is energized. If the tag wire does not indicate that the solenoid coil is energized, the problem may be in the electrical circuit.

clutch

Test the maximum pressure of the oil in the torque converter lockup clutch. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. If there is no pressure in the torque converter lockup clutch, there may be a problem with the pilot supply to the modulating valve for the torque converter lockup clutch. Test the function of the torque converter lockup clutch solenoid.

77 Power Train Testing and Adjusting Section If the initial pressure is too low, the load piston spring or the setting of the modulating valve may be incorrect.

Illustration 83

g00808385

If the solenoid is functioning correctly and the pilot supply to the modulating valve is within the specifications, load piston (8) or selector piston (9) may be sticking, or load piston spring (10) may be weak or broken. Remove the modulating valve and inspect the modulating valve for damage. Refer to Disassembly and Assembly, RENR5139, “Power Train”. If the pressure in the torque converter lockup clutch is lower than the specification, there are a number of possible causes.

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

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

If the initial pressure is too high, it is probable that there is an incorrect load piston spring, or that the setting of the modulating valve is incorrect. Remove the modulating valve and inspect the spring. Measure the rate of the spring. Refer to Specifications, RENR5133, “Power Train”. If the rate of the spring is correct, shims (13) must be added or removed from behind the load piston spring. Refer to Table 12 for the correct shims to use in order to adjust the initial pressure setting of the modulating valve. Table 12

• Load piston orifice (12) may be blocked.

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

• Load piston (8) may be sticking within selector

Pt. No. for Shims

Thickness

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)

piston (9).

• Load piston spring (10) may be broken or weak. Test the initial pressure for the torque converter lockup clutch. Refer to Systems Operation, Testing and 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 load piston plug is installed correctly, the load piston orifice could be blocked. it will be necessary to remove the modulating valve in order to inspect the internal components for damage or for blockages. Disassembly and Assembly, RENR5139, “Power Train”

Testing and Adjusting the Initial Pressure for the Torque Converter Lockup Clutch The problems that are listed above may also contribute to providing an incorrect initial pressure.

g00811113

Illustration 84

(1)

Change in Initial Pressure

Before an adjustment is performed, be certain that the valve springs are not weak or broken.

Carry out the adjustment of the modulating valve and repeat the tests for initial pressure and for maximum pressure.


Testing the Transmission Clutches Before testing and adjusting the individual valves for the transmission clutches, it is important to determine that the various components of the selector and pressure control valve are functioning correctly. Perform the procedures that are provided earlier in this section in order to determine that the main relief pressure and the pilot pressure for the transmission hydraulic control are correct.

Testing the Upshift and the Downshift Solenoids The upshift solenoid and the downshift solenoids are supplied with oil by the transmission oil pump. Use the following procedure in order to test the function of the upshift solenoid and the downshift solenoid.

1. Connect suitable test gauges to the test points in order to test the upshift pressure and the downshift pressure. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. 2. Connect a suitable gauge to the test point for the transmission oil pump pressure. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”.

7. Observe the gauges. The gauge for the transmission oil pump pressure and for downshift solenoid (16) must read the same value. The gauge for upshift solenoid (15) must read 0 kPa (0 psi). If the gauge for the downshift solenoid does not read the same value as the gauge for the pressure at the transmission oil pump, there is a fault with the downshift solenoid valve. If the gauge for the upshift solenoid is reading the same value as the gauge for the transmission oil pump pressure, then there is a fault with the upshift solenoid valve.

8. If the solenoid does not appear to function, disconnect the connector for the solenoid valve. Check the resistance of the windings of the coil in the solenoid. The resistance of the windings in the solenoid should be 32.6 ± 1.6 . If the resistance of the windings is outside the specifications replace the solenoid.

9. Stop the engine and raise the cab. 10. With the key start switch in the ON position, use a tag wire to check that the solenoid coil of the downshift solenoid is energized. If the tag wire is attracted to the solenoid coil, this indicates that the solenoid coil is energized. If the tag wire does not indicate that the solenoid coil is energized, the problem may be in the electrical circuit. 11. Connect the wiring for the upshift solenoid to the downshift solenoid and connect the wiring for the downshift solenoid to the upshift solenoid.

Illustration 85

g00810205

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

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

13. Ensure that the parking brake is engaged and press the service brake pedal.

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

14. Start the engine. Run the engine at low idle in NEUTRAL.

5. Start the engine. Run the engine at low idle in NEUTRAL. 6. Ensure that the parking brake is engaged and press the service brake pedal.

Note: The engine will be turning against the torque converter and the transmission will shift to SEVENTH gear. 15. Observe the gauges. The gauge for the transmission oil pump pressure and for the upshift solenoid must read the same value. The gauge for the downshift solenoid must read 0 kPa (0 psi).

79 Power Train Testing and Adjusting Section If the gauge for the upshift solenoid does not read the same value as the gauge for the transmission oil pump pressure, there is a fault with the upshift solenoid valve. If the gauge for the downshift solenoid is reading the same value as the gauge for the transmission oil pump pressure, there is a fault with the downshift solenoid valve.

Test the maximum pressure of the oil in the transmission 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 the pressure control valve.

Testing the Pilot Supply for Transmission Clutches

16. Stop the engine. 17. Raise the cab. 18. With the key start switch in the ON position, use a tag wire to check that the solenoid coil of the upshift solenoid is energized. If the tag wire is attracted to the solenoid coil, this indicates that the solenoid coil is energized. 19. If the solenoid does not appear to function, disconnect the connector for the solenoid valve. Check the resistance of the windings of the coil in the solenoid. The resistance of the windings in the solenoid should be 32.6 ± 1.6 .

Test the pressure of the pilot supply to the individual valves. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. If there is no pilot supply pressure to the individual valves, the neutralizer valve may not be functioning correctly. Test the function of the neutralizer valve. If the neutralizer valve is functioning correctly, there may be a problem with the downshift solenoid or the upshift solenoid. If the neutralizer valve, the upshift solenoid and the downshift solenoid are functioning correctly, there may be a blockage in the screen that is inside the selector spool.

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

20. Return the wiring harness to the correct solenoids. Disconnect the test gauges and lower the cab.

Testing and Adjusting the Individual Valves for Clutch Engagement The correct engagement of the clutches in the transmission planetary is dependent upon the correct operation and adjustment of the individual valve in the pressure control valve of the transmission hydraulic control system. Clutch engagement is dependent upon two factors, the supply of pilot oil to the individual valves in the pressure control valve and the supply of pressurized oil for clutch engagement. The supply of pilot oil to the individual valves is controlled by the selector spool in the selector and pressure control valve. The following tests are required in order to determine the correct function of the individual valves for the transmission clutches:

• Maximum pressure in the transmission clutches • Initial pressure in the transmission clutches • Pilot pressure to the individual valves

Illustration 86

g00810977

Remove the selector spool and clean the screen. If the pilot supply to the individual valves is within the specifications, load piston (17) or selector piston (18) may be sticking, or load piston spring (19) may be weak or broken. Remove the individual valve and inspect the components for damage. Refer to Disassembly and Assembly, RENR5139, “Power Train”. If the pressure in the transmission clutch is lower than the specification, there are a number of possible causes.

80 Power Train Testing and Adjusting Section If the initial pressure is too high, it is probable that there is an incorrect load piston spring, or that the setting of the modulating valve is incorrect. Remove the modulating valve and inspect load piston 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 load piston spring. Refer to Table 13 for the correct shims to use in order to adjust the initial pressure setting of the modulating valve.

Illustration 87

g00808493

• The initial pressure for the transmission clutches may be incorrect.

• Load piston plug (20) may not be installed. • Load piston orifice (21) may be blocked. • Load piston (17) may be sticking within selector piston (18).

• Load piston spring (19) may be broken or weak. If problems occur with the engagement of transmission clutches, it is first necessary to test the primary pressures in the clutches. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. If the initial pressures are correct and the load piston plugs are installed correctly, the load piston orifice could be blocked. it will be necessary to remove the modulating valve in order to inspect the internal components for damage or for blockages. Disassembly and Assembly, RENR5139, “Power Train”

Testing and Adjusting the Initial Pressure For The Transmission Clutches The problems that are listed above may also contribute to providing an incorrect initial pressure. If the initial pressure is too low, the load piston springs may be incorrect, or the setting of the modulating valve may be incorrect.


Shims for the Pressure Control Valve Pressure Change per Shim Station

A

B

C

E

F

G

H

3

1

2

5

4

6

7

Pressure change

Pressure change

Pressure change

Pressure change

Pressure change

Pressure change

Pressure change

17 kPa (2.5 psi)

14 kPa (2.0 psi)

17 kPa (2.5 psi)

(1)

Engaged Clutch Thickness of Shim

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)

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)

56 kPa (8.1 psi)

45 kPa (6.5 psi)

53 kPa (7.7 psi)

53 kPa (7.7 psi)

109 kPa (15.8 psi)

87 kPa (12.6 psi)

103 kPa (14.9 psi)

103 kPa (14.9 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)

5J-1036 Shim

0.80 mm (0.031 inch) (1)

98 kPa (14.2 psi)

87 kPa (12.6 psi)

125 kPa (18.2 psi)

Station “D”is not used.

Table 14

Specifications and Identification of the Components of the Pressure Control Valve Location of the Load Piston Body (1)

A

B

C

E

F

G

H

Thickness Of The Load 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 (0.180 inch)

4.58 mm (0.180 inch)

Color of the Outer Spring Of the Load Piston

Light blue color

Light green color

Yellow color

Light blue color

Light blue color

Light blue color

Light blue color

Color of the Inner Spring Of the Load Piston

Light green color

Light blue color

Light blue color

Yellow color

Orange color

Light blue color

Light blue color

Size of the Decay Orifice

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 (0.062 inch)

-

Color of the Decay Orifice

Green color

Red color

Green color

Red color

Red color

Green color

-

(1)

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

Carry out the adjustment of the modulating valve and repeat the tests for initial pressure and for maximum pressure.

82 Power Train Testing and Adjusting Section i01558815

Transmission Shift Points Test SMCS Code: 3030-081

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

Table 15

Tools Needed 8T-5200

FT-2796

3. Remove the wiring harness from the two transmission output speed sensors (2). Connect a 8T-5200 Signal Generator to the two transmission output speed sensors. Use a FT-2796 Connector Harness.

Qty

Generator and Counter Signal Group

1

Connector Harness

1

5. Lower the cab. Ensure that the connector harness is not trapped. 6. Ensure that the parking brake control is in the ENGAGED position.


Illustration 90

Illustration 88

g00810044

2. Disconnect the wiring harness from the torque converter lockup clutch solenoid (1). Note: This will allow testing of the shift points for the transmission without disconnecting the drive shaft from the transmission planetary.

g00764819

7. Connect a computer with ET software to the diagnostics socket by using the communications adapter. The diagnostics socket is located at the right side of the seat for the operator. 8. Turn the engine start switch to the ON. Start the engine. Switch on the computer and open up the ET software.

9. Check that the computer detects the three electronic control modules. 10. Select “Transmission”. 11. Use ET in order to check that the service brakes and the parking brake are functioning correctly. 12. When you have ensured that the service brakes and the parking brake are functioning correctly, set ET to monitor the engine output speed, the transmission output speed and the actual gear. 13. Press and hold the service brakes. Illustration 89

g00810031

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

83 Power Train Testing and Adjusting Section Note: The engine will be turning against the torque converter, so there may be some small movement and vibration of the machine.

Table 16

Modified Shift Points At Nominal Engine Speed

15. Start the signal generator. Refer to Special Instruction, SEHS8579, “8T-5200 Signal Generator”. 16. Observe the actual gear indicator. 17. Observe the computer and increase the frequency of the signal from the signal generator until the torque converter lockup clutch attempts to engage. As the solenoid is not connected this will not occur. , It will be possible to observe the attempt of the ECM to engage the torque converter lockup clutch by using ET. Record the frequency of the signal from the signal generator as the ECM attempts to engage the torque converter lockup clutch. Refer to Table 16 and Table 17 for the correct shift points. 18. Increase the frequency of the signal from the signal generator until the transmission shifts to second gear. Record the frequency of the signal from the signal generator as the transmission shifts to second gear. Refer to Table 16 and Table 17 for the correct shift points. 19. Increase the frequency of the signal from the signal generator and observe the shift points for each of the transmission gears. 20. Once the transmission is in SEVENTH gear, reduce the frequency of the signal from the signal generator. Record the frequency of the signal from the signal generator as the transmission moves from SEVENTH gear to SIXTH gear.

Upshift

Signal Generator Frequency

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


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


1C to 1L

218

1 to 2

315

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

2 to 3

430

3 to 4

583

22. Move the transmission control to the NEUTRAL position and stop the engine.

4 to 5

784

5 to 6

1063

23. Compare the shift points that were recorded with the shift points that are provided in Table 16 and Table 17.

6 to 7

1329

Downshift


7 to 6

1317

6 to 5

978

5 to 4

721

Use the information in Table 16 for this procedure.

4 to 3

537

Table 17 provides the normal transmission shift points.

3 to 2

396

2 to1

289

1L to 1T

194

The shift points for the transmission are modified when certain actions are carried out. Engaging the brakes will result in the modification of the transmission shift points. Table 16 contains these modified shift points.

84 Power Train Testing and Adjusting Section 24. Once the test has been completed, remove the connector harness from the transmission and replace the wiring harness for the transmission output speed sensors. Replace the wiring harness for the torque converter lockup clutch solenoid. i01522493

Interaxle Differential - Test SMCS Code: 3287-081

Select the interaxle differential lock and test the pressure of the oil at test point (1). Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. If both pressures are below the specification, it is possible that relief valve (3) is not functioning correctly. Replace the relief valve and test the oil pressures again.

Testing The Solenoid

The interaxle differential lock is controlled by the solenoid and relief valve group that is mounted on the transfer gear. The solenoid and relief valve group features a solenoid valve that controls the oil pressure to the interaxle differential lock and to the solenoid valve that controls the oil pressure to the axle differential locks. A relief valve is also included in the solenoid and relief valve group in order to regulate the maximum oil pressure to the differential locks. Refer to Systems Operation, Testing and Adjusting, “Machine Preparation for Troubleshooting” before you perform any testing and adjusting or troubleshooting. Prior to starting with checks on the interaxle differential, use Caterpillar ET in order to diagnose any fault codes that may be present. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR3442, “Power Train Electronic Control System”.

Testing The Oil Supply To the Interaxle Differential

Illustration 92

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To test the function of solenoid (2) in the solenoid and relief valve group, run the engine at low idle and test the pressure at test point (1). Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. Observe the gauge and select the interaxle differential lock. If a rise in the pressure is noted, then the solenoid is allowing oil to the interaxle differential lock. If a pressure rise is noted, the solenoid and the related electrical circuit are functioning correctly. If there is no rise in the pressure, then the solenoid plunger is not moving. If a pressure rise is not noted, use a tag wire to check that the solenoid coil is energized. If the tag wire is attracted to the solenoid coil, this indicates that the solenoid coil is energized. The problem is in the solenoid cartridge. The problem could be a bent solenoid stem, a screen that is dirty or plugged, or a spring that is weak or broken.

Illustration 91

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Test the supply pressure for the transfer gear at test point (1). Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”.

If the tag wire does not indicate that the solenoid coil is energized, the problem may be in the electrical circuit. Test the interaxle differential lock. If the solenoid does not function correctly, the problem may lie with the switch for the interaxle differential lock or with the wiring harness of the machine.

85 Power Train Testing and Adjusting Section If the solenoid does not appear to function, disconnect the connector for the solenoid valve. Check the resistance of the windings of the coil in the solenoid. The resistance of the windings in the solenoid should be 32.6 ± 1.6 . If the resistance of the windings is outside the specifications replace the solenoid.

Pressure In The Interaxle Differential Lock

Prior to starting with checks on the axle differentials, use Caterpillar ET in order to diagnose any fault codes that may be present. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR3442, “Power Train Electronic Control System”. Visually inspect the lines to the axle differentials and inspect the components of the control system. Inspect the oil in the system for the transfer gear and the differential locks. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”.

Testing The Oil Supply To The Axle Differentials

If the solenoid and relief valve group is functioning correctly and the pressure to the interaxle differential is correct, a failure of the interaxle differential to lock could be due to leakage past the seals of the clutch. A failure could also be a result of damage to the internal components of the interaxle differential. Inspect the oil filter and the magnetic screen for debris that may indicate damage to the internal components of the clutch for the interaxle differential. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”. i01528327

Differential - Test SMCS Code: 3258-081

The axle differential locks can only be selected if the interaxle differential lock is also selected. Oil to the solenoid valve for the axle differential locks is supplied by the solenoid valve for the interaxle differential lock. Both the solenoid valves are located in the solenoid and relief valve group that is mounted on the transfer gear. Test the supply pressure to the solenoid and relief valve group. Refer to Systems Operation, Testing and Adjusting, “Interaxle Differential - Test”. Test the operation of the solenoid in the solenoid and relief valve group that controls the interaxle differential. Refer to Systems Operation, Testing and Adjusting, “Interaxle Differential - Test”. If oil is being supplied to the solenoid valve, test the solenoid valve for correct operation.

Testing the Solenoid To test the solenoid valve that controls the axle differentials, test the pressure of the oil supply to the solenoid valve and test the pressure of the oil supply from the solenoid valve to the axle differentials. The solenoid valve for the axle differentials is located above the oil filter for the transfer gear on the inside of the front frame assembly. Illustration 93

g00793260

The axle differential locks are controlled by solenoid valve (1) that is mounted on solenoid and relief valve group (2). The solenoid valve controls the flow of the oil from the solenoid and relief valve group to the clutches for the axle differential locks when the solenoid is activated. Refer to Systems Operation, Testing and Adjusting, “Machine Preparation for Troubleshooting” before you perform any testing and adjusting or troubleshooting. Illustration 94

g00793263

86 Power Train Testing and Adjusting Section 1. Disconnect line (3) from the elbow in the front axle and insert 6V-9508 Face Seal Plug into the line.

5. Select the axle differential locks. The pressure that is displayed on the gauge that is connected to the line (4) must rise to the same value as the pressure that is displayed on the gauge that is connected 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 if a pressure is not displayed on the gauge that is connected to the solenoid valve.

Illustration 95

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

If a pressure rise is not noted, use a tag wire to check that the solenoid coil is energized. If the tag wire is attracted to the solenoid coil, this indicates that the solenoid coil is energized. The problem is in the solenoid valve. The problem could be a bent solenoid stem, a screen that is dirty or plugged, or a spring that is weak or broken. If the tag wire does not indicate that the solenoid coil is energized, the problem may be in the electrical 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 in the solenoid. The resistance of the windings in the solenoid should be 32.6 ± 1.6 . If the resistance of the solenoid windings is outside the specifications replace the solenoid. If the resistance of the solenoid windings is within the specifications, the problem may lie with the switch for the axle differential locks or with the wiring harness of the machine.

Illustration 96

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3. Install the correct hose assembly from the 1U-5482 Pressure Adapter Group on test point (5). Attach the opposite end of the hose assembly to one of the 0 to 3400 kPa (0 to 580 psi) pressure gauges in the 1U-5481 Pressure Gauge Group. 4. Start the engine and operate the engine at low idle. Select the interaxle differential lock. Observe the pressure gauges. The gauge that is connected to line (4) should not read a pressure. With the oil at normal operating temperature, the correct pressure must be displayed on the gauge that is connected to test point (5). Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”.

Testing The Pressure In The Axle Differential Locks Test the pressures for the individual axle differential locks. Refer to Systems Operation, Testing and Adjusting, “Power Train Pressures”. If the pressure in an individual axle differential lock is observed to be lower than the specification, there may be an internal leak in the axle. Check the level of the oil in the axle. Refer to Operation and Manual, SEBU7498. If the level of the oil in the axle is higher than the specification, there may be a leak in the seals on the piston of the axle differential lock or there is a leak in the lines for the axle differential lock that are inside the axle. Repair the seals or repair the damaged line.

87 Power Train Testing and Adjusting Section If the pressure in an individual axle differential lock is observed to be within the specification, the piston in the axle differential lock clutch may be sticking or there may be damage to the plates and to the disks in the axle differential lock. Inspect the oil in the axle for debris that may indicate damage to the axle differential lock. Refer to Systems Operation, Testing and Adjusting, “Visual Inspection”. Debris in the oil may indicate damage to the axle differential. Remove the axle differential and inspect the axle differential for damage. Refer to Disassembly and Assembly, RENR5139, “Differential - Disassemble and Assemble”.

88 Power Train Index Section

Index D Differential - Test.................................................... 85 Testing The Oil Supply To The Axle Differentials ...................................................... 85 Testing The Pressure In The Axle Differential Locks................................................................ 86 Testing the Solenoid........................................... 85 Differential (Center Axle) ....................................... 15 Differential (Front and Rear Axle) .......................... 13 Differential Troubleshooting ................................... 53 All Three Axle Differentials Will Not Lock When The Axle Differential Locks Are Engaged......... 53 The Axle Differential On One Or More Axles Will Not Lock When The Differential Lock Switch Is Engaged........................................................... 54 F Final Drive ............................................................. 18 G General Information............................................... Tractor Arrangement .......................................... Trailer Arrangement ........................................... General Troubleshooting Information .................... Graphic Color Codes .............................................

5 5 5 42 4

Output Transfer Gears Lubrication System ........... 28 Charging and Scavenging Pump for the Output Transfer Gears and Differential Locks .............. 28 Magnetic Screen for the Output Transfer Gears.. 29 Oil Filter for the Output Transfer Gears.............. 29 Solenoid and Relief Valve .................................. 29 P Power Train Electronic Control System ................. 24 Electronic Control Module.................................. 27 Power Train Electronic Control System.............. 26 Sensors In The Power Train............................... 27 Power Train Hydraulic System............................... 19 Output Transfer Gears and Differentials............. 22 Torque Converter and Transmission .................. 19 Power Train Pressures........................................... 55 Output Transfer Gears and Differential Lock Pressures......................................................... 66 Pressures For The Transmission Hydraulic Control System ............................................................. 59 Specifications For The Oil Pressures In The Power Train ................................................................. 69 Torque Converter Pressures .............................. 55 Pressure Control Valve (Transmission).................. 30 Transmission Pressure Control Valve ................ 30 R Rotary Actuator (Transmission) ............................. 40

I Important Safety Information ................................. 2 Interaxle Differential............................................... 11 Interaxle Differential - Test..................................... 84 Pressure In The Interaxle Differential Lock........ 85 Testing The Oil Supply To the Interaxle Differential ........................................................ 84 Testing The Solenoid ......................................... 84 Interaxle Differential Troubleshooting .................... 52 The Interaxle Differential Does Not Disengage.. 52 The Interaxle Differential Does Not Engage ...... 52

S

M

T

Machine Preparation for Troubleshooting.............. 42

Table of Contents................................................... 3 Testing and Adjusting ............................................ 55 Testing and Adjusting Section ............................... 42 Torque Converter................................................... 6

O Operational Checks ............................................... 44 Output Transfer Gears ........................................... 9

Selector and Pressure Control Valve (Transmission) ..................................................... 37 Neutralizer Valve ................................................ 38 Priority Reduction Valve..................................... 38 Relief Valve ........................................................ 39 Rotary Selector Spool........................................ 38 Torque Converter Inlet Relief Valve.................... 39 Systems Operation Section ................................... 4

89 Power Train Index Section Torque Converter Troubleshooting ........................ 45 The Torque Converter Lockup Clutch Does Not Disengage and the Engine Dies at Low Speed............................................................... 46 The Torque Converter Lockup Clutch Does Not Engage............................................................. 45 The Torque Converter or the Transmission is Overheating...................................................... 45 Transmission Hydraulic Control ............................. 23 Transmission Hydraulic Control - Test and Adjust.. 73 Testing the Transmission Clutches..................... 78 Torque Converter ............................................... 75 Transmission Hydraulic Control System ............ 73 Transmission Planetary ......................................... 8 Transmission Planetary Troubleshooting............... 47 Troubleshooting the Transmission...................... 47 Transmission Shift Points - Test............................. 82 Troubleshooting ..................................................... 42 V Visual Inspection ................................................... 43



Systems Operation Testing and Adjusting CAT 740 Articulated

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