Troubleshooting

Machine Preparation for Troubleshooting

SMCS Code: 3000-035

Refer to the following warnings and notice for all inspections and tests of the power train. If the source of the problem is not determined, perform the inspections and tests. Perform the inspections and tests in sequential order. For all tests, the power train oil must be at normal operating temperature.

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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, perform the procedure that follows before testing and adjusting the power train.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

1. Move the machine to a smooth, horizontal location that is away from operating machines and away from personnel.

NOTE: Permit only one operator on the machine. Keep all other personnel away from the machine or in the operator's sight.

2. Put the transmission control in the NEUTRAL position and any speed position. Engage the primary steering/transmission lock lever (STIC steer machines) or the transmission neutral lock (wheel steer machines).

3. Engage the parking brake. Place wheel blocks in front of the wheels and behind the wheels.

4. Lower the bucket or the attachments to the ground.

5. Stop the engine.

6. Install the steering frame lock pin.

7. Move the hydraulic control lever several times through the full range of travel. This will relieve any pressure that may be present in the implement hydraulic system.

8. Move the STIC steering control several times in both directions to release the pressure in the steering system.

9. Depress the breaker relief valve on the hydraulic tank in order to release the hydraulic oil pressure.

10. The pressure in the hydraulic system has been released. Lines and components can be removed.

Troubleshooting can be complex. A list of some of the possible problems and corrections are on the following pages.

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. Remember that a problem is not necessarily caused by one part, but by the relation of one part with other parts. This list can not provide all possible problems and corrections. Service personnel must find the problem and the source of the problem. Then, complete the necessary repairs.

Perform a visual inspection first. If the visual checks are completed but the problem has not been identified, perform operational checks. If the problem is not understood, perform instrument tests. This procedure will help to identify power train problems.

Visual Inspection

SMCS Code: 3000-035

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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth level surface. Lower the bucket and or attachments to the ground. Stop the engine and engage the parking brake. Block the wheels and install the steering frame lock pin. Turn the battery disconnect switch to the OFF position and remove the key. Place a Special Instruction, SEHS7332, "Do Not Operate" tag at the battery disconnect switch location to inform personnel that the machine is being worked on.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Escaping fluid under pressure, even a pin-hole size leak, can penetrate body tissue, causing serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

NOTE: If the machine will not move, check the transmission control circuit breaker on the circuit breaker panel in the operator's station.

A visual inspection of the power train and its components is the first step when a diagnosis of a problem is made. During these checks, if necessary, use a magnet to separate ferrous (iron) particles from non-ferrous particles (O-ring seals, aluminium, bronze, etc.).

1. Check the oil level in the differentials and final drives.

2. Check the oil level in the transmission. Look for air or water in the oil. Many problems in the transmission are caused by low oil level or air in the oil. Add oil to the transmission if it is needed. Refer to the Operation and Maintenance Manual, for recommended oil grade and viscosity.

a. Air (bubbles) may be caused by a loose or damaged fitting that allows air to enter the suction side of the system along with allowing oil to leak out. Air may also be the result of gears agitating oil in the sump if the transmission oil level is too high (overfill).

b. Coolant in the oil can be caused by a leaking transmission oil cooler. Water may enter the system if the filler cap or dipstick is not properly installed.

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

NOTE: If oil can leak out of a fitting or connection, air can leak in. Air in the system can be as harmful as not enough oil.

4. Remove the drain plug in the bottom of the output transfer gear case. Remove the suction hose from the bottom of the torque converter updrive housing. This will drain all of the oil out of the transmission system. Remove and clean the suction screens. Inspect the oil and suction screens for foreign material. Remove and inspect (cut apart if necessary) the transmission oil filter for foreign material.

NOTE: There is an oil filter bypass valve on the inlet side of the transmission oil filter. The oil filter bypass valve will open and let oil bypass the oil filter element whenever the pressure difference between inlet oil and outlet oil through the oil filter is above 248 ± 21 kPa (36 ± 3 psi). Any oil that does not flow through the filter element flows directly into the hydraulic control circuit. This dirty oil may cause restrictions in valve orifices, sticking valves, etc.

a. Rubber particles indicate seal or hose failure.

b. Shiny steel particles indicate mechanical failure or gear wear of the transmission or pumps.

c. A heavy accumulation of fibrous material indicates worn clutch discs in the transmission.

d. Aluminium particles indicate torque converter wear or failure, clutch piston wear, or worn control valve body, selector spools, or load piston in the transmission control valve.

e. Iron or steel chips indicate broken components in transmission.

NOTE: If any of the above particles are found during any visual check, all components of the transmission hydraulic system must be cleaned. Do not use any damaged parts. Any damaged parts must be removed and new parts installed.

5. The drive shaft(s) and universal joints must be free to rotate except when cold oil causes a resistance. If the shafts are not free to turn, disconnect them and see if the transmission and the torque converter updrive gears will turn.

Power Train Troubleshooting

SMCS Code: 3000-035

Schematic for the Transmission Hydraulic System (Shown with the Transmission in Neutral and the Engine Stopped)
(1) No. 2 clutch solenoid. (2) No. 3 clutch solenoid. (3) Oil cooler. (4) Transmission lubrication passage. (5) No. 6 clutch solenoid. (6) No. 1 clutch solenoid. (7) No. 5 clutch solenoid. (8) No. 4 clutch solenoid. (9) Torque converter outlet relief valve. (10) Flow control orifice. (11) Torque converter. (12) Converter inlet ratio valve. (13) Slug. (14) Slug. (15) Modulating relief valve. (16) Direction selection spool. (17) Transmission oil filter. (18) Second and fourth speed selector spool. (19) Oil pump. (20) Pressure differential valve. (21) Load piston. (22) Orifice. (23) First and third speed selector spool. (24) Screen. (25) Reservoir. (A) Pressure tap for lubrication. (B) Pressure tap for converter outlet. (C) Pressure tap for converter inlet [P3]. (D) Pressure tap for speed clutches [P1]. (E) Pressure tap for pump. (F) Pressure tap for direction clutches [P2].

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Escaping fluid under pressure, even a pin-hole size leak, can penetrate body tissue, causing serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

Show/hide table

NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

Operational Checks

Disengage the parking brake. Operate the machine in each direction and in all speeds. Note the noises that are not normal and find the source of the noises. If the machine is not operating correctly, refer to the "Troubleshooting Problem List" below.

Troubleshooting Problem List

Transmission Problem List

1. The transmission does not operate in any speed or slips in all speeds.

2. The transmission overheats.

3. Pump noise not normal.

4. Noise in the transmission that is not normal.

5. Transmission operates in FORWARD only.

6. Transmission operates in REVERSE only.

7. Transmission does not operate in FIRST SPEED FORWARD or REVERSE.

8. Transmission does not operate in SECOND SPEED FORWARD or REVERSE.

9. Transmission does not operate in THIRD SPEED FORWARD or REVERSE.

10. Transmission does not operate in FOURTH SPEED FORWARD or REVERSE.

11. Low pressure at pressure taps for P1 (speed) and P2 (direction) clutches in all speeds and directions.

12. Low pressure at P2 clutch pressure tap in REVERSE speeds.

13. Low pressure at P2 clutch pressure tap in FORWARD speeds.

14. High pressure at pressure taps for P1 (speed) and P2 (direction) clutches in all speeds and directions.

15. Pressure differential between P1 and P2 not correct.

16. Clutch engagement is sudden (rough shifts).

17. Clutch engagement is slow (slow shifts-all gears).

18. Clutch engagement is slow (slow shifts-all FORWARD gears or all REVERSE gears or any one gear in both FORWARD and REVERSE).

19. Transmission stays engaged when the neutralizer is actuated (left brake pedal is pushed).

20. Transmission engages but the machine does not move and the engine lugs down.

21. With the engine running and the parking brake "ENGAGED", the action alarm does not sound when the transmission control is put into either a FORWARD or REVERSE direction.

22. Backup alarm does not sound when transmission control is put in REVERSE.

23. Low stall speed.

24. High stall speed in both directions.

25. High stall speed in one speed or in one direction.

Torque Converter Problem List

26. High converter pressure.

27. Low converter pressure.

28. The torque converter overheats.

Differential Problem List

29. Constant noise in the differential.

30. Noise occurs in the differential at different intervals.

31. Noise only occurs during turns.

32. Lubricant is leaking.

33. Drive wheels do not turn (universal joint turns).

Troubleshooting

NOTE: In the following section, when components are referenced with a number, refer to the "Schematic for the Transmission Hydraulic System", on the previous page.

NOTE: This machien is equipped with an Electronic Transmission Control (ETC). The ETC has built-in system diagnostics to detect faults in the transmission electronic system. The diagnostics are displayed on the Caterpillar Monitoring System message display when the system is placed in the service mode. For Systems Operation, Testing and Adjusting information on the transmission electrical system, make reference to Electronic Transmission Control System, for the machine that is being serviced.

Probable Causes of Power Train Problems

Transmission Problem List

Problem 1: The transmission does not operate in any speed or slips in all speeds.

Probable causes:

1. Transmission control circuit breaker has tripped.

2. Problem in the electrical circuit for the transmission.

3. Low system voltage.

4. Transmission shift control switch is defective.

5. Low oil pressure caused by:

a. Low oil level.

b. Restriction in the oil flow circuit such as a dirty oil strainer.

c. Oil pump failure.

d. Air leaks on the inlet side of the pump.

e. Leakage inside the transmission: Worn or damaged seals around the clutch piston.

f. Modulating relief valve (15) stuck open.

6. Torque converter failure.

7. Mechanical failure in the transmission.

8. Clutch discs and plates are worn too much.

9. Transmission neutralizer switch is open.

Problem 2: The transmission overheats.

Probable causes:

1. Low coolant level in the engine radiator.

2. Wrong application for the machine. There is too much torque converter slippage caused by too much load.

3. Incorrect transmission gear for load on machine. Shift to a lower gear.

4. Defective temperature gauge.

5. Incorrect (high or low) oil level.

6. Oil cooler or lines are restricted.

7. Clutch slips too much:

a. Low oil pressure. See Problem 1:

Transmission does not operate in any speed or slips in all speeds.

b. Damaged clutch.

8. Low oil flow caused by pump wear or leakage in the hydraulic system.

9. Air mixed in the oil. Air leaks on the intake side of the pump.

10. Magnetic pump inlet screen plugged.

11. Torque converter inlet ratio valve (12) is stuck open, which causes low oil flow through the torque converter.

12. Clutch or clutches not fully released (drag):

a. Warped plates or discs.

b. Broken or weak return spring.

Problem 3: Pump noise not normal.

Probable causes:

1. A loud sound at short time periods indicates that foreign material is in the transmission hydraulic system.

2. A constant loud noise indicates pump failure.

3. Air at the inlet side of the pump.

Problem 4: Noise in the transmission that is not normal.

Probable causes:

1. Transmission components are worn or damaged:

a. Damaged gears.

b. Worn teeth of clutch plates and/or clutch discs.

c. Slipping clutch plates and disc noise.

d. Other component parts that are worn or damaged.

Problem 5: Transmission operates in FORWARD only.

Probable causes:

1. Transmission REVERSE solenoid valve (6) is inoperative.

2. Problem in the electrical circuit.

3. REVERSE clutch not engaged (slips) because of:

a. Low oil pressure because of leaking seals on piston.

b. Discs and plates have too much wear.

c. Broken components.

4. Selector spool (16) is stuck.

Problem 6: Transmission operates in REVERSE only.

Probable causes:

1. Transmission FORWARD solenoid valve (1) is inoperative.

2. Problem in the electrical circuit.

3. FORWARD clutch not engaged (slips) because of:

a. Low oil pressure because of leaking seals on piston.

b. Discs and plates have too much wear.

c. Broken components.

4. Selector spool (16) is stuck.

Problem 7: Transmission does not operate in FIRST SPEED FORWARD or REVERSE.

Probable causes:

1. FIRST SPEED solenoid valve (5) is inoperative.

2. Problem in the electrical circuit.

3. FIRST SPEED clutch not engaged (slips) because of:

a. Low oil pressure because of leaking seals on piston.

b. Discs and plates have too much wear.

c. Broken components.

4. Selector spool (23) stuck.

Problem 8: Transmission does not operate in SECOND SPEED FORWARD or REVERSE.

Probable causes:

1. SECOND SPEED solenoid (7) is inoperative.

2. Problem in the electrical circuit.

3. SECOND SPEED clutch not engaged (slips) because of:

a. Low oil pressure because of leaking seals on piston.

b. Discs and plates have too much wear.

c. Broken components.

4. Selector spool (18) stuck.

Problem 9: Transmission does not operate in THIRD SPEED FORWARD or REVERSE.

Probable causes:

1. THIRD SPEED solenoid (8) is inoperative.

2. Problem in the electrical circuit.

3. THIRD SPEED clutch not engaged (slips) because of:

a. Low oil pressure because of leaking seals on piston.

b. Discs and plates have too much wear.

c. Broken components.

4. Selector spool (23) stuck.

Problem 10: Transmission does not operate in FOURTH SPEED FORWARD or REVERSE.

Probable causes:

1. FOURTH SPEED solenoid (2) is inoperative.

2. Problem in the electrical circuit.

3. FOURTH SPEED clutch not engaged (slips) because of:

a. Low oil pressure because of leaking seals on piston.

b. Discs and plates have too much wear.

c. Broken components.

4. Selector spool (18) is stuck.

Problem 11: Low pressure at pressure taps for P1 (speed) and P2 (direction) clutches in all speeds and directions.

Probable causes:

1. Modulating relief valve (15) stuck.

2. Low oil pressure. See Problem: Transmission does not operate in any speed or slips in all speeds.

3. Load piston (21) springs weak, damaged, or missing. Spacers missing.

Problem 12: Low pressure at P2 clutch pressure tap in REVERSE speeds.

Probable causes:

1. Too much leakage in the REVERSE clutch piston seals.

Problem 13: Low pressure at P2 clutch pressure tap in FORWARD speeds.

Probable causes:

1. Too much leakage in the FORWARD clutch piston seals.

Problem 14: High pressure at pressure taps for P1 (speed) and P2 (direction) clutches in all speeds and directions.

Probable causes:

1. Operation of modulating relief valve (15) sticky.

2. Load piston (21) stuck.

3. Wrong load piston springs. Too many spacers.

4. Worn slug (13) or worn modulating relief valve (15) bore.

Problem 15: Pressure differential between P1 and P2 not correct.

Probable causes:

1. Operation of pressure differential valve (20) not correct:

a. Weak, damaged or wrong spring.

Problem 16: Clutch engagement is sudden (rough shifts).

Probable causes:

1. Operation of pressure differential valve (20) not correct:

a. Weak, damaged or wrong spring.

2. Load piston (21) stuck.

3. Load piston springs are wrong or damaged.

Problem 17: Clutch engagement is slow (slow shifts-all gears).

Probable causes:

1. Screen orifice for the load piston is dirty (plugged).

2. Low oil pressure. See Problem: Transmission does not operate in any speed or slips in all speeds.

3. Load piston springs are weak or have damage.

4. Modulating relief valve (15) is stuck.

Problem 18: Clutch engagement is slow (slow shifts-all FORWARD gears or all REVERSE gears or any one gear in both FORWARD and REVERSE).

Probable causes:

1. Low clutch pressure because of leaking seals on the piston for the affected gear.

Problem 19: Transmission stays engaged when the neutralizer is actuated (left brake pedal is pushed).

Probable causes:

1. Transmission neutralizer switch is faulty.

2. Problem in electrical circuit.

Problem 20: Transmission engages but the machine does not move and the engine lugs down.

Probable causes:

1. Machine brakes are locked up.

2. Mechanical failure in a differential (front or rear).

3. Mechanical failure in a final drive.

4. Gears in transmission do not turn because of:

a. Mechanical failure in transmission.

b. Too many clutches engaged.

Problem 21: With the engine running and the parking brake ENGAGED, the action alarm does not sound when the transmission control is put into either a FORWARD or REVERSE direction.

Probable causes:

1. Failure of the action alarm.

2. Failure in the wiring:

a. Loose or defective connector.

b. Broken wire.

3. Transmission control group problem.

Problem 22: Backup alarm does not sound when the transmission control is put in REVERSE.

Probable causes:

1. Failure of backup alarm circuit breaker.

2. Failure of backup alarm.

3. Failure in the wiring:

a. Loose or defective connector.

b. Broken wire.

4. Transmission control group problem.

Problem 23: Low stall speed.

Probable causes:

1. Engine performance is not correct.

2. Cold oil.

Problem 24: High stall speed in both directions.

Probable causes:

1. Engine performance is not correct.

2. Low oil level.

3. Air in the oil.

4. Clutches are slipping.

5. Torque converter failure.

Problem 25: High stall speed in one speed or in one direction.

Probable causes:

1. There is a leak in the clutch circuit.

2. There is a clutch failure in the speed or direction that there is high stall speed.

Torque Converter Problem List

Problem 26: High converter pressure.

Probable causes:

1. A restriction inside the converter.

2. A restricted oil passage or oil cooler.

3. Converter inlet ratio valve (12) is stuck closed.

Problem 27: Low converter pressure.

Probable causes:

1. Converter inlet ratio valve (12) is stuck open.

2. Low pump flow or pressure. See Problem:

Transmission does not operate in any speed or slips in all speeds.

Problem 28: The torque converter overheats.

Probable causes:

1. Wrong application for the machine. There is too much torque converter slippage caused by too much load.

2. Incorrect transmission gear for load on machine. Shift to a lower gear.

3. Incorrect (high or low) oil level in the transfer gear case.

4. Low coolant level in the engine radiator.

5. Restrictions in the oil cooler or lines.

6. Not enough oil to the converter because of:

a. Converter inlet ratio valve (12) bypassing too much flow.

b. Low pump flow or pressure. See Problem:

Transmission does not operate in any speed or slips in all speeds.

Differential Problem List

Problem 29: Constant noise in the differential.

Probable causes:

1. Lubricant above or below the proper level.

2. Wrong type of lubricant.

3. Wheel bearings are out of adjustment or are defective.

4. The ring gear and pinion do not have correct tooth contact.

5. The ring gear and pinion are damaged or worn.

6. There is too much or too little pinion to gear backlash.

7. Loose or worn pinion bearings.

8. Loose or worn side bearings.

Problem 30: Noise occurs in the differential at different intervals.

Probable causes:

1. Ring gear does not run even:

a. Bolts on the ring gear are not tight.

b. The ring gear is warped.

2. Loose or broken differential bearings.

Problem 31: Noise only occurs during turns.

Probable causes:

1. The differential pinion gears are too tight on the retainer pins or the pinion shaft.

2. Side gears are too tight in the differential case.

3. Differential pinion or side gears are defective.

4. Thrust washers are worn or damaged.

5. Too much backlash between the side and pinion gears.

Problem 32: Lubricant is leaking.

Probable causes:

1. Loss through axle shafts:

a. Lubricant above the proper level.

b. Wrong type of lubricant.

c. Axle housing breather is restricted.

d. Axle shaft oil seal is installed wrong or is damaged.

2. Loss at pinion shaft:

a. Lubricant above the proper level.

b. Wrong type of lubricant.

c. Axle housing breather is restricted.

d. Pinion oil seal worn or is not installed correctly.

e. Universal joint flange loose on the pinion shaft.

Problem 33: Drive wheels do not turn (universal joint turns).

Probable causes:

1. Broken axle shaft.

2. Ring gear teeth are damaged.

3. Side gear or differential pinion are broken.

4. Differential pinion shaft or retainer pins are broken.

Torque Converter Hydraulic System - Test and Adjust

SMCS Code: 3133-025; 3133-081; 3073-025; 3073-081

Schematic for the Torque Converter Hydraulic System
(1) Oil filter. (2) Torque converter. (3) Transmission hydraulic controls. (4) Body of relief valve for converter outlet. (5) Relief valve for converter outlet. (6) Oil pump. (7) Screen. (8) Oil reservoir. (9) Oil cooler. (10) Torque converter scavenge pump. (A) Pressure tap for oil pump (on filter). (B) Pressure tap for converter inlet [P3]. (C) Pressure tap for relief valve. (D) Pressure tap for converter outlet. (E) Pressure tap for lubrication.

Transmission Hydraulic Control
(B) Pressure tap for converter inlet [P3].

Torque Converter Outlet Relief Valve
(D) Pressure tap for converter outlet.

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

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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, perform the procedure that follows before testing and adjusting the hydraulic system.

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel.

2. Lower the bucket or attachments to the ground.

3. Engage the parking brake.

4. Put blocks in front of and behind the wheels to prevent movement.

5. Install the steering frame lock pin.

6. Allow only authorized personnel on the machine and keep other personnel off the machine and in clear view of the operator.

NOTE: All tests and all adjustments must be made while the transmission oil is at normal operating temperature.

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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.

Torque Converter Outlet Relief Valve
(4) Relief valve body. (11) Relief valve. (12) Spacers.

Transmission Hydraulic System - Test and Adjust

SMCS Code: 3030-025; 3030-081; 3073-025; 3073-081

Schematic for the Transmission Hydraulic System (Shown with the Transmission in Neutral and the Engine Stopped)
(1) No. 2 clutch solenoid. (2) No. 3 clutch solenoid. (3) Oil cooler. (4) Transmission lubrication passage. (5) No. 6 clutch solenoid. (6) No. 1 clutch solenoid. (7) No. 5 clutch solenoid. (8) No. 4 clutch solenoid. (9) Torque converter outlet relief valve. (10) Flow control orifice. (11) Torque converter. (12) Converter inlet ratio valve. (13) Slug. (14) Slug. (15) Modulating relief valve. (16) Direction selection spool. (17) Transmission oil filter. (18) Second and fourth speed selector spool. (19) Oil pump. (20) Pressure differential valve. (21) Load piston. (22) Orifice. (23) First and third speed selector spool. (24) Screen. (25) Reservoir. (A) Pressure tap for lubrication. (B) Pressure tap for converter outlet. (C) Pressure tap for converter inlet [P3]. (D) Pressure tap for speed clutches [P1]. (E) Pressure tap for pump. (F) Pressure tap for direction clutches [P2].

Right Side of the Transmission Case (Viewed from Under the Machine)
(A) Pressure tap for transmission lubrication.

Transmission Hydraulic Control
(C) Pressure tap for converter inlet [P3]. (D) Pressure tap for speed clutches [P1]. (F) Pressure tap for direction clutches [P2]. (G) Plug for load piston [LP].

Torque Converter Updrive Housing
(E) Pressure tap for transmission oil pump.

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

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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, perform the procedure that follows before testing and adjusting the hydraulic system.

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel.

2. Lower the bucket or attachments to the ground.

3. Put blocks in front of and behind the wheels to prevent movement.

4. Install the steering frame lock pin.

5. Allow only authorized personnel on the machine and keep other personnel off the machine and in clear view of the operator.

6. Disengage the parking brake.

NOTE: All tests and all adjustments must be made while the transmission oil is at normal operating temperature.

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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.

Transmission Selector and Pressure Control Valve
(21) Load piston. (26) Spacers.

NoSPIN Differential - Test

SMCS Code: 3265-081

After the NoSPIN differential has been assembled, test the operation of the differential. Perform this test before the differential is installed on the machine.

1. Install the NoSPIN differential in the case.

2. Install the case in a stand or in a vise in order to keep the case from rotating.

3. Install both axles in the case.

NoSPIN Differential
(1) Case. (A) Axle. (B) Axle.

4. Apply a force in a clockwise direction on both axles.

5. Keep the force on axle (A) and turn axle (B) in a counterclockwise direction. The NoSPIN differential will make a small noise and axle (B) will turn freely.

NOTE: Make sure that the force is kept on axle (A).

6. Keep the force on axle (A) and turn axle (B) in a clockwise direction. The NoSPIN differential will make a small noise and axle (B) will not turn farther.

Test for the NoSPIN Differential

7. Put a force in a counterclockwise direction on both axles.

8. Keep the force on axle (A) and turn axle (B) in a clockwise direction. The NoSPIN differential will make a small noise and axle (B) will turn freely.

NOTE: Make sure that the force is kept on axle (A).

9. Keep the force on axle (A) and turn axle (B) in a counterclockwise direction. The NoSPIN differential will make a small noise and axle (B) will not turn farther.

10. Perform Steps 4 through 9 again, but hold axle (B) while you turn axle (A).

If the NoSPIN differential does not act correctly, inspect the components and check the assembly procedure.