This is intended as a reference for locating and correcting problems that may occur in the power train. Since each machine is different, you may need to call us at 800-872-3392 with specific problems and questions.

In all instances, visual checks of the machine should be made first and then operational checks before proceeding to instrumentation tests.

VISUAL CHECKS

1. Check the oil level of the transmission and steering hydraulic system.
2. Check the oil level of the final drives.
3. Inspect all external oil lines, connections and external valving for leaks or damage.
4. Check the transmission control linkage and steering and brake control linkages for damage and/or adjustment.
5. Check to be certain the track is not too tight.
6. Rotate the universal joint in both directions by hand.  It should rotate freely except when cold oil causes clutch drag.  If it does not turn, disconnect the universal joint and determine if the torque converter or range transmission is locked.
7. Check the magnetic strainer, filter, and scavenge pump screen for foreign material.
1. Iron or steel particles indicate possible transmission, transfer gear or bevel gear failure.
2. Bronze-colored particles indicate a clutch failure, either a steering clutch or transmission clutch.
3. Bright steel particles in the filter indicate a pump failure.
4. Aluminum particles indicate a torque converter failure.
5. Rubber particles indicate a damaged seal or hose.

If metal or rubber particles are found, clean all components in the hydraulic system and recondition the damaged components.  If no particles are found, the machine can usually be operated without damage to the components.

OPERATIONAL CHECKS

With the engine running, move the transmission speed selector lever to all positions.  The detents should be felt in each position.
Operate the machine in all speeds.  Listen for unusual noises and determine their source.  Lock the brakes and stall the torque converter in each speed.  If the universal joint turns, the transmission clutches are slipping.  Refer to the OPERATIONAL CHECK LIST for “problems” and “probable causes.”

OPERATIONAL CHECK LIST

Transmission

PROBLEM: Does not operate in any speed or slips in all speeds.
PROBABLE CAUSE:

1. Low oil pressure caused by:
1. Low oil level.
2. Control linkage broken, loose or incorrectly adjusted.
3. Oil pump or oil pump drive failure.
4. Air leaks on inlet side of pump.
5. Leakage within the transmission.
6. Hydraulic system pressure relief valve incorrectly adjusted or stuck open.
7. Load piston, check valve, or differential valve stuck.
2. Mechanical failure in transmission.
3. Torque converter failure.
4. Transfer gear failure or bevel gear failure.

PROBLEM: Operates in reverse speeds only or forward speeds only.
PROBABLE CAUSE:

1. Control linkage broken, loose or incorrectly adjusted.
2. Worn discs and plates and/or broken parts in the directional clutch.
3. Excessive leakage in connections and/or clutch piston seals of directional clutch.

PROBLEM: Transmission does not shift.
PROBABLE CUASE:

1. Low oil level.
2. Low clutch pressures.
3. Incorrect linkage adjustment or worn or broken parts.

PROBLEM: Sluggish shifting.
PROBABLE CAUSE:

1. Low oil pressure.
2. Incorrectly adjusted internal and external control system linkages.
3. Air leaks on inlet side of pump.
4. Load piston or check valve sticking in pressure control valve.

PROBLEM: Rough Shifting.
PROBABLE CAUSE:

1. Incorrectly adjusted control system linkage.
2. Incorrect initial setting of modulating valve.
3. Sticking load piston and/or check valve.
4. Weak or broken valve springs.

PROBLEM: Does not operate in a particular speed (forward or reverse) or operates in one speed only.
PROBABLE CAUSE:

1. Control linkage broken, loose or incorrectly adjusted.
2. Worn discs and plates and/or broken components of the clutch in question.
3. Excessive leakage in connections and/or clutch piston seals of the clutch in question.
4. Clutch plates broken, binding ring gear of the clutch in question. (Torque converter will stall in all other speeds.)

PROBLEM: Transmission remains in gear when selector lever is in NEUTRAL.
PROBABLE CAUSE:

1. Control linkage broken, loose ore incorrectly adjusted.
2. Directional clutches not releasing.

PROBLEM: Transmission engages, torque converter stalls and engine under load condition.  Machine does not move.
PROBABLE CAUSE:

1. Locked transmission.
1. Broken parts.
2. One or more clutches incorrectly engaged.
2. Broken teeth on bevel pinion or bevel gear.
3. Broken teeth on pinion and/or gears in final drives.

PROBLEM: Overheating of the transmission.
PROBABLE CAUSE:

1. Low oil level.
2. Oil cooler core partially plugged.
3. Excessive clutch drag.
4. Low oil flow as a result of a worn oil pump or extreme leakage in the hydraulic system.

PROBLEM: Unusually noisy pump.
PROBABLE CAUSE:

1. An intermittent loud popping sound which gives the impression that foreign materials are passing through the pump is caused by pump cavitations.
2. A constant loud milling or gritting noise is an indication of pump failure.

Torque Converter

PROBLEM: Torque converter overheating.
PROBABLE CAUSE:

1. Improper operation of machine.  Constant overloading.
2. Faulty temperature gauge.
3. Cooling system of machine faulty.
4. Mechanical failure of torque converter.
5. Excessive oil build-up in the torque converter cover around converter due to:
1. Scavenge pump failure.
2. Clogged screen.
3. Excessive leakage through torque converter.
6. Insufficient oil supply to the converter caused by:
1. Excessive leakage in the transmission and steering system.
2. Faulty pump.
3. Torque converter inlet relief valve set too low or leaking.
4. Clogged oil cooler or lines

Steering

PROBLEM: Machine will not turn in one direction.
PROBABLE CAUSE:

1. Steering control linkage incorrectly adjusted.
2. Excessive leakage in circuit between control valve and steering clutch piston or between piston seals.

PROBLEM: Machine will not steer in either direction.
PROBABLE CAUSE:

1. Low pump output.
2. Leakage in the lines between the hydraulic system relief valve and the control valve.
3. Excessive leakage in the transmission
4. Hydraulic system relief valve set low or leaking.
5. Incorrectly adjusted steering and brake linkage.

PROBLEM: Machine veers in either direction with both steering clutches engaged.
PROBABLE CUASE:

1. Incorrectly adjusted pedal linkage.
2. Worn steering clutch plates.
3. Weak or broken steering clutch springs.
4. Broken steering clutch spring retaining bolts.
5. Worn serration on driving and driven steering clutch drums causing plates to “hang up.”

PROBLEM: Sluggish steering.
PROBABLE CAUSE:

1. Incorrectly adjusted, worn or broken linkage.
2. Worn brake lining.
3. Low pump output.
4. Worn serrations on driving and driven steering clutch drums causing plates to “hang up.”

These are general troubleshooting guidelines courtesy of the Caterpillar service manual.  If you need further assistance please call TradeWater Machinery at 800-872-3392.