- Service brakes not calibrated
- Contamination of the hydraulic system oil
- Insufficient pressure oil to the brakes
- Steering charge pump pressure is not correct
- Failed brake components
- Brake control valve
- Proportional solenoid valve
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Escaping fluid under pressure, even a pinhole 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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Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates. |
Ensure that the brakes are calibrated. Refer to Specifications, Systems Operations, and Testing and Adjusting, UENR4065, "Calibration".
Contamination Of The Hydraulic System Oil
If the symptom is not active or if the symptom is intermittent, oil contamination may be the problem.
Change the hydraulic system oil. Change the oil filter element and clean the screens. Refer to Operation and Maintenance Manual, SEBU9127, "Hydraulic System Oil - Change".
Insufficient Pressure Oil To The Brakes
The operator controls the brake control valve with a service brake foot pedal. When the operator releases the service brake foot pedal, the brakes are released by oil pressure sent from the brake control valve to the brakes. The pressure reading when the brakes are released should be greater than
Reference: Refer to Specifications, Systems Operations, and Testing and Adjusting, UENR4065, "Brake Pressure - Test" to determine if the brake pressure is correct.
Expected Results
- The pressure reading when the brakes are released is greater than
2500 kPa (365 psi) .
Results
- OK: The pressure reading when the brakes are released is greater than
2500 kPa (365 psi) . Proceed to "Failed Brake Components".
- NOT OK: The pressure reading when the brakes are released is not greater than
2500 kPa (365 psi) . Proceed to "Steering Charge Pump Pressure Is Not Correct".
Steering Charge Pump Pressure Is Not Correct
Brake pressure is supplied by the steering charge pump. The steering charge pump is part of the hydraulic oil system.
Reference: Refer to Specifications, Systems Operations, and Testing and Adjusting, UENR4065, "Piston Pump (Steering Charge and Pilot Pressure) - Test and Adjust" to determine if the steering charge pump pressure is correct.
Expected Results
- The steering charge pump pressure is correct.
Results
- OK: The steering charge pump pressure is correct. Inspect the brake control valve. Proceed to "Brake Control Valve".
- NOT OK: The steering charge pump pressure is not correct. Refer to Specifications, Systems Operations, and Testing and Adjusting, UENR4065, "Piston Pump (Steering Charge and Pilot Pressure) - Test and Adjust".
Disassemble the brakes and check the following components of the brakes for failure:
- Brake housing
- Reaction plate
- Brake pistons
- Belleville springs
- Stationary ring gear
- Seals
- Splines
- Friction discs
- Brake plates
- Shuttle valve
Replace any damaged components, if necessary.
Calibrate the brakes.
Reference: Refer to Specifications, Systems Operations, and Testing and Adjusting, UENR4065, "Calibration".
- Disassemble the brake control valve and inspect the valve for damage.
- Repair the components and/or replace the components, if necessary.
- Calibrate the brakes.
Reference: Refer to Specifications, Systems Operations, and Testing and Adjusting, UENR4065, "Calibration".
- Recheck the brake pressure.
Reference: Refer to Specifications, Systems Operations, and Testing and Adjusting , UENR4065, "Brake Pressure - Test".
Expected Results
- The brake pressure is correct.
- The original problem is resolved.
Results
- OK: Stop.
- NOT OK: If no problems with the brake control valve are observed, the probable causes analyzed in this procedure did not identify the cause of the problem. If the pressure is correct, but the original symptom still exists, proceed to "Proportional Solenoid Valve".
- Replace the proportional solenoid valve.
- Calibrate the brakes.
Reference: Refer to Specifications, Systems Operations, and Testing and Adjusting, UENR4065, "Calibration".
- Check the brake pressure.
Reference: Refer to Specifications, Systems Operations, and Testing and Adjusting , UENR4065, "Brake Pressure - Test".
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.