Challenger 35, Challenger 45 and Challenger 55 Agricultural Tractors Implement, Steering and Brake Hydraulic Systems Caterpillar

Troubleshooting for the Implement Hydraulic System

Problem List

• "The temperature of the hydraulic oil in the common sump is too high."

• "The pump makes unusual noises."

• "There is a large amount of air in the oil."

• "The pump pressure is too low."

• "The pump pressure is too high."

• "There is a pause before pressure is achieved in all the circuits."

• "The signal pressure is not zero when all of the valves are in the HOLD position."

• "Any implement moves when the control lever is in the HOLD position."

• "The hitch relief valve is too noisy."

• "The hitch drifts too much or the implement drifts too much."

• "The implement falls slightly when the implement is moving from a partially raised position to a fully raised position."

• "The cycle times are too slow for all implements."

• "The cycle time is too slow for an implement."

• "The cycle time is too fast for an implement."

• "The implement control valve does not return to the HOLD position when the hydraulic cylinders reach the end of the stroke."

• "The hitch moves slowly or the hitch does not move."

• "The hitch moves when the control lever has not been moved."

• "The hitch moves too fast."

Probable Causes

The temperature of the hydraulic oil in the common sump is too high.

1. Check the actual temperature of the oil.

   1. Insert a thermometer into the oil filler tube.

   2. If the temperature is below 107 °C (224 °F), there is an electrical problem with the temperature sensing system. Refer to Systems Operation/Testing and Adjusting, RENR1781.

2. Check the oil cooler.

   1. Make sure that the oil cooler is not packed with debris.

3. Determine if the oil cooler bypass valve is stuck open.

   1. Determine the cause. If necessary, repair the oil cooler bypass valve.

4. Check the techniques of the operator. The load on the system may be too high.

   Note: Make sure that the engine is running at high idle. This will ensure that the oil cooler is working at full capacity.

   1. Change the operating techniques in order to reduce the load on the system.

5. Check the hydraulic oil level in the common sump. The level may be too low.

   1. Check the hydraulic oil level in the common sump in order to determine if there is enough oil in the hydraulic tank. The oil level should be between the "ADD" and "FULL" marks on the dipstick.

   2. Check for oil aeration by taking an oil sample. If aeration is found, see "There is a large amount of air in the oil".

6. The outside air temperature may be too hot.

   1. Change the operating techniques in order to reduce the load on the system.

7. Verify that the pump proceeds to low pressure standby when the implements and the hitch are not being operated.

   1. Perform the low pressure standby test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".
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   Illustration 1	g00513202
   (1) Flow compensator spool (2) Orifice

   2. If the pump does not proceed to low pressure standby, make sure that flow compensator spool (1) moves freely inside the compensator valve. Also, make sure that orifice (2) is free of debris.

   3. If necessary, repair the failure.

8. Make sure that the correct viscosity of oil is in the system.

   1. Refer to Operation and Maintenance Manual, SEBU7204.

9. Verify that the pressure compensator spool valve opens at the correct oil pressure.

   1. Perform the high pressure stall test for the implement pump. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".

10. Check the implement hydraulic pump for wear.

    1. Perform the Pump Efficiency Check.

11. Make sure that the multifunction valves are adjusted correctly.

    1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

12. Make sure that the charge relief valve is adjusted correctly.

    1. Perform the pressure test for the charge oil of the steering system. Refer to Systems Operation/Testing and Adjusting, "Steering System Charge Oil Pressure Test".

13. Check for a restriction in an oil passage.

    1. Determine the cause. If necessary, repair the machine.

14. Check the steering pump for excessive wear.

    1. Perform the Pump Efficiency Check.

15. There may be a problem with the transmission hydraulic system.

    1. Refer to Systems Operation/Testing and Adjusting, RENR1774, "Troubleshooting".

The pump makes unusual noises.

1. Make sure that the correct viscosity of oil is in the system.

   1. Refer to Operation and Maintenance Manual, SEBU7204.

2. Determine if the hitch relief valve opens at low oil pressure.

   1. If necessary, replace the hitch relief valve.

3. Check for a loose connection of the oil line on the inlet side of the pump. Check for aeration of the oil.

   1. Tighten the connection, if necessary.

4. Check for pump wear.

   1. Perform the Pump Efficiency Check.

There is a large amount of air in the oil.

1. Check for a leak in the oil line between the common sump and the pump.

   1. Repair the leak, if necessary.

2. The air was not correctly purged from the hydraulic system after assembly, inspection or testing.

   1. Cycle the system in order to purge the air from the hydraulic system.

3. Determine if the hitch relief valve opens at low oil pressure.

   1. If necessary, replace the hitch relief valve.

4. Check for leakage around the seals in the hydraulic cylinders.

   1. If necessary, repair the seals.

The pump pressure is too low.

1. Determine if the flow compensator spool is adjusted correctly.

   1. Perform the Margin Pressure Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Test".

2. Make sure that the pressure compensator spool is adjusted correctly.

   1. Perform the High Pressure Stall Test on the implement pump. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Test".

3. There is a leak in the signal network.

   1. Perform the Resolver Network Check.

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Illustration 2	g00513198
(3) Flow spool spring

4. Inspect flow spool spring (3) and verify that the spring is not broken.

5. Check for pump wear.

   1. Perform the Pump Efficiency Check.

6. Ensure that the swashplate is not blocked and ensure that the actuator spring is not broken.

   1. Repair the pump, if necessary.

The pump pressure is too high.

1. Determine if the flow compensator spool in the compensator valve is adjusted correctly.

   1. Perform the Margin Pressure Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Test".

2. Make sure that the pressure compensator spool is adjusted correctly.

   1. Perform the High Pressure Stall Test on the implement pump. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Test".

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Illustration 3	g00513202
(1) Flow compensator spool (2) Orifice

3. Make sure that flow compensator spool (1) moves freely.

   1. Repair the compensator valve, if necessary.

4. Make sure that orifice (2) is free of debris.

5. Make sure that the pump is destroking. Ensure that the swashplate is not blocked and ensure that the actuator piston is not stuck.

   1. Repair the pump, if necessary.

There is a pause before pressure is achieved in all the circuits.

1. There may be air in the signal network.

   1. Purge the air from the hydraulic system by cycling the system several times.

2. Make sure that the flow compensator spool in the compensator valve is adjusted correctly.

   1. Perform the Margin Pressure Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Test".

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Illustration 4	g00513202
(1) Flow compensator spool (2) Orifice

3. Make sure that flow compensator spool (1) moves freely.

   1. Repair the compensator valve, if necessary.

4. Make sure that orifice (2) is free of debris.

The signal pressure is not zero when all of the valves are in the HOLD position.

1. Make sure that all controls are in the HOLD position.

   1. Refer to Operation and Maintenance Manual, SEBU7204.

2. Make sure that the signal network is connected to the sump.

   1. Verify that all of the lines are connected properly.

Any implement moves when the control lever is in the HOLD position.

1. Check for a leak in a connection between the implement control valve and the cylinders.

   1. Repair the connection, if necessary.

2. Check the implement control valve and the valve spool for excessive wear.

   1. Repair the valve, if necessary.

3. Check the piston seal in the hydraulic cylinder for excessive wear.

   1. Repair the piston seal, if necessary.

The hitch relief valve is too noisy.

1. Verify that the hitch relief valve is adjusted correctly.

   1. If necessary, replace the hitch relief valve.

2. Make sure that the flow compensator spool in the compensator valve is adjusted correctly.

   1. Perform the Margin Pressure Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".

   2. Repair the compensator valve, if necessary.

3. Make sure that the springs in the hitch relief valve have not failed.

   1. Replace the springs, if necessary.

The hitch drifts too much or the implement drifts too much.

Note: The hitch falls slightly when the draft/position control knob is turned to the position control detent.

1. Check for leakage around the piston seals in the hydraulic cylinders.

   1. Repair the piston seals, if necessary.

2. Check the setting of the hitch relief valve.

   1. Adjust the relief valve, if necessary.

3. Make sure that the spool in the control valve is centered correctly.

   1. Inspect the control valve for a broken spring.

   2. Make sure that the control spool moves freely.

   3. Repair the control valve, if necessary.

4. Check for leakage around the seals of the hitch relief valve.

   1. Repair the seals, if necessary.

5. Check for excessive wear on the control spool.

   1. Replace the spool, if necessary.

The implement falls slightly when the implement is moving from a partially raised position to a fully raised position.

1. There may be air in the signal network.

   1. Purge the air from the implement hydraulic system by cycling the system several times.

2. Make sure that the flow compensator spool in the compensator valve is adjusted correctly.

   1. Perform the Margin Pressure Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".

   2. Inspect spring (3) and verify that the spring is not broken.

3. Make sure that the pressure compensator spool is operating correctly.

   1. Perform the High Pressure Stall Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".
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   Illustration 5	g00573630
   (3) Spring for flow compensator spool (4) Spring for pressure compensator spool

   2. Replace spring (4) if the pressure compensator spool cannot be adjusted correctly.

4. Make sure that the signal passages in the main stem of the control valve are not blocked.

   1. Repair the control valve, if necessary.

5. Check the control valve for foreign material.

   1. Clean the control valve, if necessary.

The cycle times are too slow for all implements.

1. Make sure that the flow control knobs are adjusted correctly.

   1. Refer to Operation and Maintenance Manual, SEBU7204.

2. Make sure that the flow compensator spool is adjusted correctly.

   1. Perform the Margin Pressure Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".

   2. Repair the system, if necessary.

3. Make sure that the pressure compensator spool is adjusted correctly.

   1. Perform the High Pressure Stall Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".
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   Illustration 6	g00513253
   (4) Spring for pressure compensator spool

   2. Replace spring (4) if the pressure compensator spool cannot be adjusted correctly.

4. Check for blockage in the signal network. Check for leakage in the signal network.

   1. Perform the resolver network check.

   2. Repair the signal network, if necessary.

5. Make sure that the pump fully strokes. Ensure that the actuator piston moves freely and ensure that the swashplate is not blocked.

   1. Repair the pump, if necessary.

The cycle time is too slow for an implement.

1. Make sure that the flow control knobs are adjusted correctly.

   1. Refer to Operation and Maintenance Manual, SEBU7204.

2. Make sure that the implement valve cable is adjusted correctly.

   1. Refer to Specifications, RENR1792, "Implement Valve Cable Adjustment".

3. Make sure that the signal that is flowing to the compensator valve is not blocked.

   1. Perform the Margin Pressure Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".

   2. If necessary, adjust the flow compensator spool in order to set the correct margin pressure. If the correct margin pressure cannot be achieved, there may be blockage in the signal network.

   3. Repair the signal network, if necessary.

4. Check for leakage around the piston seals of the hydraulic cylinders.

   1. Repair the piston seals, if necessary.

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Illustration 7	g00513692
(5) Flow control spring

5. Check flow control spring (5) in the control valve.

   1. Replace the spring, if necessary.

6. Make sure that the pump fully strokes. Ensure that the actuator piston moves freely and ensure that the swashplate is not blocked.

   1. Repair the pump, if necessary.

The cycle time is too fast for an implement.

1. Verify the operation of the flow control spool in the implement control valve.

   1. Inspect the flow control spool for missing parts or damaged parts.

   2. Clean the flow control spool. Dirt in the hydraulic oil may cause the spool to bind.

The implement control valve does not return to the HOLD position when the hydraulic cylinders reach the end of the stroke.

1. Make sure that the detent kickout pressure is adjusted correctly.

   1. Test the detent kickout pressure. See Systems Operation/Testing and Adjusting, "Detent Kickout Pressure Test" for more information.

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Illustration 8	g00513701
(6) Spring (7) Spring

2. Inspect springs (6) and (7) in the mechanism for the kickout of the detent.

   1. Repair the mechanism, if necessary.

The hitch moves slowly or the hitch does not move.

1. Check for a fault code on the electronic monitoring center.

   1. If there is a fault code, refer to Systems Operation/Testing and Adjusting, RENR1781.

2. Verify that there is enough weight on the hitch.

   1. Add weight to the hitch in order to increase the rate of lowering.

3. Determine if the problem is electrical or hydraulic.

   1. Actuate the hitch. Use a compass to determine if the solenoids are magnetized.

   2. If the solenoids are not magnetized during the operation, there is an electrical problem. Refer to Systems Operation/Testing and Adjusting, RENR1781.

   3. If the solenoids are magnetized, proceed to Step 4.

4. Make sure that the implement hydraulic system is operating correctly.

   1. If necessary, perform the High Pressure Stall Test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".

The hitch moves when the control lever has not been moved.

1. Check for a fault code on the electronic monitoring center.

   1. If there is a fault code, refer to Systems Operation/Testing and Adjusting, RENR1781.

2. Check for a leak in the connection between the hitch valve and the hydraulic cylinders.

   1. Repair the leak, if necessary.

3. Check the piston seals in the hydraulic cylinders for excessive wear.

   1. Repair the piston seals, if necessary.

4. Check the solenoid valve for excessive wear.

   1. Repair the solenoid valve, if necessary.

5. Check the spool in the hitch valve for excessive wear.

   1. Repair the spool, if necessary.

6. Check for foreign material in the solenoid valve. Check for foreign material in the hitch valve.

   1. Repair the valves, if necessary.

7. Check the hitch relief valve for excessive wear.

   1. If necessary, replace the hitch relief valve.

The hitch moves too fast.

1. Check the electrical components of the hitch control system for correct adjustment and operation.

   1. Refer to Systems Operation/Testing and Adjusting, RENR1781.

Troubleshooting for the Steering Hydraulic System

Problem List

• "The temperature of the hydraulic oil in the common sump is high."

• "The charge oil pressure for the steering hydraulic system is not correct."

• "The pilot oil pressure from the steering control valve is not correct."

• "The steering pump oil pressure is not correct."

• "The machine turns slowly in both directions."

• "The machine turns slowly in one direction."

• "The machine turns in the opposite direction of the steering wheel in forward and/or reverse."

• "The turns of the machine are jerky or the turns are unstable."

• "The machine turns correctly during roading, but the machine turns slowly in one direction when the machine is loaded."

• "The engine lugs more than normal when you steer the machine."

• "The engine speed surges when you steer the machine."

• "The machine drifts in one direction in first gear when the engine is at low idle."

• "The steering wheel rotation is excessive before the turn begins."

Probable Causes

The temperature of the hydraulic oil in the common sump is high.

1. Check the actual temperature of the oil.

   1. Insert a thermometer into the oil filler tube.

   2. If the temperature is below 107 °C (224 °F), there is an electrical problem with the temperature sensing system. Refer to Systems Operation/Testing and Adjusting, RENR1781.

2. Check the oil cooler.

   1. Make sure that the oil cooler is not packed with debris.

3. Determine if the oil cooler bypass valve is stuck open.

   1. Determine the cause. If necessary, repair the oil cooler bypass valve.

4. Check the techniques of the operator. The load on the system may be too high.

   Note: Make sure that the engine is running at high idle. This will ensure that the oil cooler is working at full capacity.

   1. Change the operating techniques in order to reduce the load on the system.

5. Check the hydraulic oil level in the common sump. The level may be too low.

   1. Check the hydraulic oil level in the common sump in order to determine if there is enough oil in the hydraulic tank. The oil level should be between the "ADD" and "FULL" marks on the dipstick.

   2. Check for oil aeration by taking an oil sample. If aeration is found, see "There is a large amount of air in the oil".

6. The outside air temperature may be too hot.

   1. Change the operating techniques in order to reduce the load on the system.

7. Verify that the pump proceeds to low pressure standby when the implements and the hitch are not being operated.

   1. Perform the low pressure standby test. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".
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   Illustration 9	g00513202
   (1) Flow compensator spool (2) Orifice

   2. If the pump does not proceed to low pressure standby, make sure that flow compensator spool (1) moves freely inside the compensator valve. Also, make sure that orifice (2) is free of debris.

   3. If necessary, repair the failure.

8. Make sure that the correct viscosity of oil is in the system.

   1. Refer to Operation and Maintenance Manual, SEBU7204.

9. Verify that the pressure compensator spool valve opens at the correct oil pressure.

   1. Perform the high pressure stall test for the implement pump. Refer to Systems Operation/Testing and Adjusting, "Implement Pump Discharge Pressure Tests".

10. Check the implement hydraulic pump for wear.

    1. Perform the Pump Efficiency Check.

11. Make sure that the multifunction valves are adjusted correctly.

    1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

12. Make sure that the charge relief valve is adjusted correctly.

    1. Perform the pressure test for the charge oil of the steering system. Refer to Systems Operation/Testing and Adjusting, "Steering System Charge Oil Pressure Test".

13. Check for a restriction in an oil passage.

    1. Determine the cause. If necessary, repair the machine.

14. Check the steering pump for excessive wear.

    1. Perform the Pump Efficiency Check.

15. There may be a problem with the transmission hydraulic system.

    1. Refer to Systems Operation/Testing and Adjusting, RENR1774, "Troubleshooting".

The charge oil pressure for the steering hydraulic system is not correct.

1. Check the hydraulic oil level in the common sump.

   1. Check the hydraulic oil level in order to determine if there is enough oil in the common sump.

   2. The oil level should be between the "ADD" and "FULL" marks on the dipstick.

2. Make sure that the correct viscosity of oil is in the system.

   1. Refer to Operation and Maintenance Manual, SEBU7204.

3. The charge relief valve is not adjusted correctly.

   1. Perform the pressure test for the charge oil of the steering system. Refer to Systems Operation/Testing and Adjusting, "Steering System Charge Oil Pressure Test".

4. The high pressure cutoff of the multifunction valves is not adjusted.

   1. Test the high pressure cutoff of the steering system. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

5. Check the charge pump for excessive wear.

   1. Perform the pump efficiency test.

The pilot oil pressure from the steering control valve is not correct.

1. Make sure that the charge oil pressure is not too low.

   1. Test the charge oil pressure for the steering system. Refer to Systems Operation/Testing and Adjusting, "Steering System Charge Oil Pressure Test".

   2. If the charge oil pressure is too low, refer to "The charge oil pressure for the steering hydraulic system is not correct".

2. Check the operation of the pressure regulating valve.

   1. Refer to Systems Operation/Testing and Adjusting, "Steering Control Pressure Regulating Test".

   2. If the pressure regulating valve is not operating correctly, go to Step 3.

   3. If the pressure regulating valve is operating correctly, go to Step 4.

3. Check the regulating spring in the pressure reducing valve in the steering control in order to make sure that the spring is not broken.

   1. Remove the regulating spring from the pressure reducing valve in order to inspect the spring.

   2. Replace the spring, if necessary.

4. Check the steering control for correct operation.

   1. Make sure that the steering wheel rotates freely.

   2. If the steering wheel does not rotate freely, remove the steering control from the steering column. Then, check the steering control.

5. Check the diverter valve for damage. Check the diverter valve for leakage.

   1. Repair the diverter valve, if necessary.

The steering pump oil pressure is not correct.

1. Make sure that the multifunction valves are adjusted correctly.

   1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

2. Make sure that the pilot oil pressure from the steering control valve is correct.

   1. Test the pilot oil pressure from the steering control valve. Refer to Systems Operation/Testing and Adjusting, "Steering Control Pilot Oil Pressure Test".

   2. If the pilot oil pressure is not correct, refer to "The pilot oil pressure from the steering control valve is not correct".

3. Make sure that the hydraulic displacement control valve is operating correctly.

   1. Check the operation of the hydraulic displacement control valve. Refer to Systems Operation/Testing and Adjusting, "Hydraulic Displacement Control Valve Test".

   2. Check the upstroke of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump Upstroke/DeadbandTest".

4. Make sure that the charge pump is operating correctly.

   1. Check the charge oil pressure. Refer to Systems Operation/Testing and Adjusting, "Steering System Charge Oil Pressure Test".

   2. If the charge oil pressure is not correct, refer to "The charge oil pressure for the steering hydraulic system is not correct".

5. Check the pump for excessive wear.

   1. Perform the pump efficiency check.

The machine turns slowly in both directions.

1. Check for leaks in the circuit between the steering pump and the steering motor.

   1. Repair any leaks, if necessary.

2. Check the steering pump oil pressure.

   1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

   2. If the steering pump oil pressure is not correct, refer to "The steering pump oil pressure is not correct".

3. Check the steering motor for excessive wear.

   1. Test the case drain pressure of the steering motor.

The machine turns slowly in one direction.

1. Check for leaks in the circuit between the steering pump and the steering motor.

   1. Repair any leaks, if necessary.

2. Make sure that the pilot oil pressure from the steering control valve is correct.

   1. Test the pilot oil pressure from the steering control valve.

   2. If the pilot oil pressure is not correct, refer to "The pilot oil pressure from the steering control valve is not correct".

3. Make sure that the hydraulic displacement control valve is operating correctly.

   1. Check the operation of the hydraulic displacement control valve. Refer to Systems Operation/Testing and Adjusting, "Hydraulic Displacement Control Valve Test".

   2. Check the upstroke of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump Upstroke/DeadbandTest".

4. Check the tension of the belts.

   1. Refer to Systems Operation/Testing and Adjusting, RENR1774, "Track - Tension/Detension".

5. Make sure that the multifunction valves are adjusted correctly.

   1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

The machine turns in the opposite direction of the steering wheel in forward and/or reverse.

1. Make sure that power is supplied to the solenoid on the diverter valve when the machine is operated in reverse.

   1. Check the connectors.

   2. Make sure that the wiring is not damaged.

2. The oil lines that connect the steering control valve to the diverter valve are crossed.

   1. Switch the lines and test the steering.

3. The oil lines that connect the diverter valve to the steering pump are crossed.

   1. Switch the lines and test the steering.

4. Make sure that the diverter valve is operating correctly.

   1. Make sure that the spool moves freely.

   2. Make sure that the return spring is not broken.

   3. Repair the diverter valve, if necessary.

The turns of the machine are jerky or the turns are unstable.

1. Check for a large amount of air in the oil.

   1. Take a sample of oil from the sump.

   2. If there is a large amount of air in the oil, refer to "There is a large amount of air in the oil".

2. Make sure that the multifunction valves are adjusted correctly.

   1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

3. Make sure that the pressure regulating valve on the steering control valve operates correctly.

   1. Refer to Systems Operation/Testing and Adjusting, "Steering Control Pressure Regulating Test".

   2. If the pressure regulating valve is not operating correctly, check the spool and check the springs.

4. Make sure that the hydraulic displacement control valve is operating correctly.

   1. Check the operation of the hydraulic displacement control valve. Refer to Systems Operation/Testing and Adjusting, "Hydraulic Displacement Control Valve Test".

   2. Check the upstroke of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump Upstroke/DeadbandTest".

5. Check for debris in the oil.

   1. If there is debris in the oil, find the cause of the debris.

The machine turns correctly during roading, but the machine turns slowly in one direction when the machine is loaded.

1. Make sure that the multifunction valves are adjusted correctly.

   1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

2. Check the tension of the belts.

   1. Refer to Systems Operation/Testing and Adjusting, RENR1774, "Track - Tension/Detension".

The engine lugs more than normal when you steer the machine.

1. Make sure that the multifunction valves are adjusted correctly.

   1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

2. Check the techniques of the operator. The load on the system may be too high.

   1. Change the operating techniques in order to reduce the load on the system.

The engine speed surges when you steer the machine.

1. Make sure that the multifunction valves are adjusted correctly.

   1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

2. Make sure that the pilot oil pressure from the steering control is correct.

   1. Refer to Systems Operation/Testing and Adjusting, "Steering Control Pilot Oil Pressure Test".

   2. If the pilot oil pressure is not correct, refer to "The pilot oil pressure from the steering control valve is not correct".

The machine drifts in one direction in first gear when the engine is at low idle.

1. Check the tension of the belts.

   1. Refer to Systems Operation/Testing and Adjusting, RENR1774, "Track - Tension/Detension".

2. Check the deadband of the steering system.

   1. Refer to Systems Operation/Testing and Adjusting, "Steering Pump Upstroke/Deadband Test".

3. Make sure that the pilot oil pressure from the steering control is correct.

   1. Refer to Systems Operation/Testing and Adjusting, "Steering Control Pilot Oil Pressure Test".

   2. If the pilot oil pressure is not correct, refer to "The pilot oil pressure from the steering control valve is not correct".

4. Check the operation of the steering control.

   1. Refer to Systems Operation/Testing and Adjusting, "Steering Control Bench Test".

The steering wheel rotation is excessive before the turn begins.

1. Check the steering pump oil pressure.

   1. Test the high pressure cutoff of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump High Pressure Cutoff Pressure Test".

   2. If the steering pump oil pressure is not correct, refer to "The steering pump oil pressure is not correct".

2. Make sure that the hydraulic displacement control valve is operating correctly.

   1. Check the operation of the hydraulic displacement control valve. Refer to Systems Operation/Testing and Adjusting, "Hydraulic Displacement Control Valve Test".

   2. Check the upstroke of the steering pump. Refer to Systems Operation/Testing and Adjusting, "Steering Pump Upstroke/DeadbandTest".

3. Check the steering motor for excessive wear.

   1. Test the case drain pressure for the steering motor.

4. Make sure that the steering control is operating correctly.

   1. Refer to Systems Operation/Testing and Adjusting, "Steering Control Bench Test".

Troubleshooting for the Service Brake System

Problem List

• "The service brakes do not operate."

• "The service brakes slip."

• "The application of the service brakes is not smooth."

• "Too much force is required in order to depress the service brake pedal."

Probable Causes

The service brakes do not operate.

1. Make sure that the linkage for the brake pedal is not damaged.

   1. Inspect the linkage.

   2. Repair the linkage, if necessary.

2. The master cylinder is not operating correctly.

   1. Test the service brake pressure.

   2. Refer to Systems Operation/Testing and Adjusting, "Service Brake Pressure Test".

   3. If the pressure is not within specifications, repair the master cylinder.

3. Make sure that there is no air in the brake lines.

   1. Purge the air from the brake lines.

   2. Refer to Systems Operation/Testing and Adjusting, "Purge the Service Brakes".

4. The disc brakes are damaged.

   1. Inspect the brakes.

   2. Repair the brakes, if necessary.

The service brakes slip.

1. The linkage for the service brake pedal is not adjusted correctly.

   1. Adjust the linkage.

2. Make sure that the drive wheels do not have excessive wear.

3. Make sure that there is no air in the brake lines.

   1. Purge the air from the brake lines.

   2. Refer to Systems Operation/Testing and Adjusting, "Purge the Service Brakes".

4. Check the tension of the belts.

   1. Refer to Systems Operation/Testing and Adjusting, RENR1774, "Track - Tension/Detension".

5. The disc brakes may be worn.

   1. Inspect the brakes.

   2. Repair the brakes, if necessary.

The application of the service brakes is not smooth.

1. Make sure that the linkage for the brake pedal is not damaged.

   1. Inspect the linkage.

   2. Repair the linkage, if necessary.

2. The piston for the brake boost in the master cylinder may be damaged.

   1. Disassemble the master cylinder.

   2. Repair the master cylinder, if necessary.

3. The brake pistons on the disc brakes may be binding.

   1. Remove the brake piston from the brake.

   2. Clean the piston. Repair the piston, if necessary.

Too much force is required in order to depress the service brake pedal.

1. Make sure that the linkage for the brake pedal is not damaged.

   1. Inspect the linkage.

   2. Repair the linkage, if necessary.

2. Make sure that the passage from the transmission control valve to the master cylinder is not blocked.

3. The piston for the brake boost in the master cylinder may be damaged.

   1. Disassemble the master cylinder.

   2. Repair the master cylinder, if necessary.

4. The brake pistons on the disc brakes may be binding.

   1. Remove the brake piston from the brake.

   2. Clean the piston. Repair the piston, if necessary.