PL72, PL83 and PL87 Pipelayers Caterpillar

This story contains the following troubleshooting information:

• Problems with the Steering System Components

Problem List for the Steering System Components

• "The Machine Pauses Before the Machine Starts to Steer"

• "The Steering Speed is Slow in Both Directions and Oil Output of the Steering Pump is Low"

• "Steering Speed Is Slow in One Direction and the Oil Output of the Steering Pump Is Low in One Direction"

• "The Machine Has Low Turning Force in Both Directions and the Output Pressure of the Steering Pump is Low in Both Directions"

• "The Machine Has Low Turning Force in One Direction and the Pressure Output of the Steering Pump is Low in One Direction"

• "The Machine Will Not Turn in Either Direction"

• "The Pump Remains at NEUTRAL in One Direction and the Machine Does Not Turn in One Direction"

• "Steering Pump Pressures in NEUTRAL Are Too High or Too Low"

• "Steering Speed Changes with a Step or Steering Modulation is Poor"

• "The Machine Turns in the Wrong Direction"

• "The Steering is Jerky or Unstable"

• "The Machine Continues to Turn When the Steering Control Lever is Returned to NEUTRAL"

• "The Pressure or the Flow From the Steering Pump is Low"

• "The Machine Will Not Turn or the Steering Radius is Very Large"

• "The Turning Radius is Too Large in Both Directions"

• "The Turning Radius is Too Large in One Direction"

The Machine Pauses Before the Machine Starts to Steer

Probable Causes

1. The hydraulic oil is too thick or the type of oil is incorrect.

2. Steering charge pressure or flow is low.

3. The steering pump controls are suspect.

4. The orifice in the pump control is partially blocked.

5. The NEUTRAL setting for the steering pump is improperly adjusted.

The Steering Speed is Slow in Both Directions and Oil Output of the Steering Pump is Low

Probable Causes

1. Steering charge pressure or flow is low.

2. The steering pump controls are suspect.

3. The pressure setting for the pump cutoff valve is low.

4. The steering pump has failed or the pump has wear. The steering motor has failed or the motor has wear.

Steering Speed Is Slow in One Direction and the Oil Output of the Steering Pump Is Low in One Direction

Probable Causes

1. The flushing valve of the steering pump is suspect or the valve is stuck open.

2. The steering pump control is improperly adjusted or the control is suspect.

The Machine Has Low Turning Force in Both Directions and the Output Pressure of the Steering Pump is Low in Both Directions

Probable Causes

1. The cutoff pressure setting for the steering pump is too low.

2. Both pressure settings of the crossover relief and makeup valves are low or the valves are suspect.

3. Steering charge pressure is too low.

4. The steering pump or the steering motor has too much wear.

The Machine Has Low Turning Force in One Direction and the Pressure Output of the Steering Pump is Low in One Direction

Probable Causes

1. One pressure setting of a crossover relief and makeup valve is low or the valve is suspect.

2. The flushing valve of the steering pump is stuck open or the flushing valve has high leakage.

3. The steering pump or the steering motor has excessive wear or excessive leakage.

The Machine Will Not Turn in Either Direction

Probable Causes

1. The steering pump pressure or flow is low.

2. The pump cutoff valve is suspect.

3. The steering pump or the steering motor has failed.

4. The steering pump or the steering motor is loose. The steering pump or the steering motor has backed out of the drive splines.

5. The parking brake is not releasing. Check the following causes:

   1. The wiring has a fault.

   2. The brake valve spool is stuck.

   3. The brake valve has excessive internal leakage.

The Pump Remains at NEUTRAL in One Direction and the Machine Does Not Turn in One Direction

Probable Causes

1. The pump controls in the steering pump are suspect.

2. The flushing valve in the steering motor is stuck open.

3. The zero position for the steering pump is improperly adjusted.

4. The steering pump controls have excessive leakage.

Steering Pump Pressures in NEUTRAL Are Too High or Too Low

Probable Causes

1. The pressure setting of the charging valve for steering is too high or too low.

2. The setting for the pressure control valve for steering is low.

Steering Speed Changes with a Step or Steering Modulation is Poor

Probable Causes

1. The hydraulic oil is too thick or the oil is the wrong type. Warm the oil to operating temperature.

2. The steering supply flow is partially blocked.

3. A partial blockage exists in the steering pilot circuit.

4. The pump control is suspect or the control needs adjustment.

The Machine Turns in the Wrong Direction

Probable Causes

1. The harness for the pump control solenoids is incorrectly connected at the steering pump.

2. The high-pressure hoses are connected incorrectly between the steering pump and the steering motor.

The Steering is Jerky or Unstable

Probable Causes

1. The pump cutoff valve and the crossover relief and makeup valves have an undesirable interaction.

2. The hydraulic oil is too thick or the oil is the wrong type. Warm the oil to operating temperature.

3. The charging valve for steering is unstable.

The Machine Continues to Turn When the Steering Control Lever is Returned to NEUTRAL

Probable Causes

1. The adjustment of the zero position in the steering pump is not correct.

2. Adjustment of the zero position at the NEUTRAL is not correct.

3. The pump control is suspect. Check these causes:

   1. A spring in the pump control is broken.

   2. The valve spool for the pump is sticking.

4. The pump has failed.

The Pressure or the Flow From the Steering Pump is Low

Probable Causes

1. The oil level in the hydraulic tank is too low.

2. The pump inlet or the suction line is blocked or crushed.

3. The steering pump has failed or the pump is worn.

4. The pressure control valve is suspect or the valve setting is too low.

5. The charge pressure relief valve in the steering pump is suspect or the pressure setting is too low.

The Machine Will Not Turn or the Steering Radius is Very Large

Reference(PL72 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4132, "Operational Tests"

Reference(PL83 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Operational Tests"

Reference(PL87 LRC and HRC) Specifications, Systems Operation and Testing and Adjusting, UENR4141, "Operational Tests"

The operational tests can be used to find leakage in the system. The operational tests can find a valve that is failing. The operational tests can also find a pump or a motor that is failing. The speed of rod movement of the cylinders (cycle time) is a measure of the condition of the cylinders and the pump.

Probable Causes

1. The steering pump is not connected to the pump drive or the pump drive shaft is broken.

2. The oil level in the hydraulic tank is low.

3. The steering pump or the steering motor has failed.

4. The system pressure or the pilot pressure is low.

5. The parking brake is ON. Check the following causes:

   1. The oil pressure in the power train is low.

   2. The brake valve has excessive internal leakage.

6. A mechanical problem in the drive train is interfering with the steering.

The Turning Radius is Too Large in Both Directions

Probable Causes

1. The system pressure in the steering circuit is low. Check the following causes:

   1. The steering pump is faulty or worn. See Step 2.

   2. The bypass valve is suspect.

   3. The pressure control valve is set too low.

   4. The pressure control valve has excessive leakage.

   5. The steering motor is failing. See Step 3.

2. The steering pump is malfunctioning. Check the following causes:

   1. The crossover relief and makeup valve is leaking excessively.

   2. The pump controls are misadjusted or damaged.

   3. The stops are incorrect or worn.

3. The steering motor is malfunctioning. Check the following causes:

   1. The steering motor is worn or failed.

   2. The pressure control valve is suspect.

The Turning Radius is Too Large in One Direction

Probable Causes

1. The system pressure in the steering circuit is low. Check the following causes:

   1. The pressure control valve has excessive leakage.

   2. The steering pump or the steering motor is failing.

      Refer to Step 2 and Step 3.

2. The steering pump is malfunctioning. Check the following causes:

   1. The crossover relief and makeup valve is leaking.

   2. The pump controls are misadjusted or damaged.

   3. The pump is worn or failed.

3. The steering motor is malfunctioning. Check the following causes:

   1. The steering motor is worn or failed.

   2. The pressure control valve is suspect.