PL72, PL83 and PL87 Pipelayers Caterpillar

Problem List

• "The Transmission Clutch Is Engaged and the Clutch Does Not Release"

• "The Transmission Clutch Does Not Engage"

The Transmission Clutch Is Engaged and the Clutch Does Not Release

Follow this procedure if the machine seems to have a brake that is applied. Also, follow this procedure if the machine only operates in certain gears.

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Personal injury can result if the machine moves while testing. If the machine begins to move during test, reduce the engine speed immediately and engage the parking brake.

1. Check the pressures.

   1. Start the engine. Operate the engine at low idle.

   2. Push down on the service brake pedal in order to engage the brakes.

   3. Disengage the parking brake.

   4. Shift the transmission into the NEUTRAL position in order to check these clutches: No. 1, No. 2, No. 4 and No. 5. No. 3 clutch should be the only clutch that is engaged.

   5. Shift the transmission into FIRST GEAR FORWARD in order to check No. 3 clutch. No. 2 clutch and No. 5 clutch should be engaged.

   6. Measure the pressure for the clutch that does not release.
      

      Reference(PL72 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4132, "Transmission Clutch Pressure - Test"

      Reference(PL83 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Transmission Clutch Pressure - Test"

      Reference(PL87 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Transmission Clutch Pressure - Test"

      Expected Results

      • When the clutches are released, all clutch pressures are less than 138 kPa (20 psi).

      Results

      • OK: Stop. The clutch releases properly.

      • NOT OK: Proceed to Step 2.

2. Check the bolt torques for the transmission modulating valves.

   1. Check the torque of the bolts that hold the transmission modulating valves to the transmission control valve.

      Expected Results

      • The torque for the valves is correct.

      Results

      • OK: Proceed to Step 3.

      • NOT OK: Tighten the bolts or loosen the bolts to the proper torque. Check the operation of the machine for the original problem. If conditions are not resolved, proceed to Step 3.

3. Replace the transmission modulating valve.

   1. Replace the transmission modulating valve for the clutch that does not release.

   2. Calibrate the transmission modulating valves.

      Reference(PL72 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4132, "Calibration" for the appropriate calibration procedure.

      Reference(PL83 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Calibration" for the appropriate calibration procedure.

      Reference(PL87 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Calibration" for the appropriate calibration procedure.

   3. Check the operation of the machine for the original problem.

      Expected Results

      • The original problem is resolved.

      Results

      • OK: Stop.

      • NOT OK: If the original problem is still present, the cause of the problem is uncertain. Call technical support with the information that has been gathered.

The Transmission Clutch Does Not Engage

Follow this procedure if the machine does not operate in specific gears.

1. Check the system pressure.
   

   Reference(PL72 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4132, "Relief Valve (Transmission) - Test and Adjust" .

   Reference(PL83 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Relief Valve (Transmission) - Test and Adjust" .

   Reference(PL87 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Relief Valve (Transmission) - Test and Adjust" .

   Expected Results

   • The system pressure is correct.

   Results

   • OK: If the original problem has not been is not resolved, proceed to Step 3.

   • NOT OK: The cause of the problem may be the adjustment of the main relief valve. The main relief valve maintains the system pressure in the control section of the power train oil pump. Proceed to Step 2.

2. Adjust the pressure setting of the main relief valve.
   

   Reference(PL72 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4132, "Relief Valve (Transmission) - Test and Adjust" .

   Reference(PL83 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Relief Valve (Transmission) - Test and Adjust" .

   Reference(PL87 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Relief Valve (Transmission) - Test and Adjust" .

   Expected Results

   • The pressure setting of the main relief valve is correct.

   Results

   • OK: The pressure setting of the main relief valve is correct. If the original problem has not been resolved proceed to Step 3.

   • NOT OK: Proceed to Step 4.

3. Check the pressure at the clutch.
   

   Reference(PL72 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4132, "Transmission Clutch Pressure - Test" .

   Reference(PL83 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Transmission Clutch Pressure - Test".

   Reference(PL87 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Transmission Clutch Pressure - Test".

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   Personal injury can result if the machine moves while testing. If the machine begins to move during test, reduce the engine speed immediately and engage the parking brake.

   1. Start the engine. Operate the engine at low idle.

   2. Press down the service brake pedal in order to engage the brakes.

   3. Disengage the parking brake.

   4. Shift the transmission into a gear that requires the use of the clutch that is not functioning correctly.

   5. Measure the pressure at the clutch that does not engage.

      Expected Results

      • The hydraulic pressure is equal to main relief on clutches 1 through 4, or 2241 kPa (325 psi) on clutch 5 when the clutch is engaged.

      Results

      • OK: Proceed to Step 8.

      • NOT OK: Proceed to Step 5.

4. Follow the procedure in this reference.

   Refer to "System Pressure Is Low" in this module under Troubleshooting, "Power Train Oil".

   Results

   • REPAIRED, OK: The original problem is resolved. Stop.

   • NOT OK: The system pressure is correct but the problem is not resolved. Proceed to Step 5.

5. Interchange modulating valves.

   1. Interchange one of the modulating valves that should be engaged with one modulating valve that should not be engaged.

   2. Determine whether the problem follows one particular valve.

   3. Repeat the procedure for all modulating valves that affect the gear that is not functioning properly.

      Results

      • FOLLOWS: The problem follows one valve. Proceed to Step 6.

      • DOES NOT FOLLOW: Proceed to Step 7.

6. Replace the transmission modulating valve.

   1. Replace the transmission modulating valve for the clutch that does not engage.

   2. Calibrate the transmission modulating valves.
      

      Reference(PL72 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4132, "Calibration" for the appropriate calibration procedure.

      Reference(PL83 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Calibration" for the appropriate calibration procedure.

      Reference(PL87 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Calibration" for the appropriate calibration procedure.

   3. Check the operation of the machine for the original problem.

      Expected Results

      • The original problem is resolved.

      Results

      • OK: Stop.

      • NOT OK: Proceed to Step 8.

7. Restore the modulating valve.

   1. Restore the modulating valves to the original locations. Note the suspect valve and the original location.

   2. Check the operation of the machine for the original problem.

      Expected Results

      • The original problem is resolved.

      Results

      • OK: Stop.

      • NOT OK: Proceed to Step 8.

8. Inspect the clutch.

   1. Disassemble the clutch and inspect the clutch for failure.
      

      Reference(PL72 LRC) Disassembly and Assembly, UENR4144, "Transmission"

      Reference(PL72 HRC) Disassembly and Assembly, UENR4143, "Transmission"

      Reference(PL83 LRC) Disassembly and Assembly, UENR4141, "Transmission"

      Reference(PL83 HRC) Disassembly and Assembly, UENR4139, "Transmission"

      Reference(PL87 LRC) Disassembly and Assembly, UENR4142, "Transmission"

      Reference(PL87 HRC) Disassembly and Assembly, UENR4140, "Transmission"

   2. Check for excessive wear on friction discs and clutch plates.

   3. Inspect the piston seals.

   4. Repair the components or replace the components, if necessary.

   5. Check the operation of the machine for the original problem.

      Expected Results

      • The original problem is resolved.

      Results

      • OK: Stop.

      • NOT OK: The cause of the problem is uncertain. Call technical support with the information that has been gathered. Stop.