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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the brake system. |
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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand. |
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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause 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 machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of all fluids according to local regulations and mandates. |
This section provides probable causes to known problems. Since there may be several probable causes, specific inspections or instrument tests may be recommended. These inspections and tests will help to identify the causes that are most probable.
Note: Make sure that you use an oil with the correct viscosity for the operating conditions. To determine the correct oil viscosity, refer to Operation and Maintenance Manual, "Lubricant Viscosities and Refill Capacities" for your machine.
Problem List
Problem List for the Service Brake
- The front service brakes do not operate.
- The rear service brakes do not operate.
- Service brakes slip.
- The service brakes are not applied evenly.
- Too much force needed to push the brake pedals.
Problem List for the Parking Brake
- The parking brake does not hold the machine stationary.
- The parking brake does not engage when the parking brake control lever is actuated.
Problem 1
The front service brakes do not operate.
Probable causes
- Check the level of the hydraulic fluid in the brake system.
- Check for proper hydraulic fluid in the brake system.
- The lines to the front service brakes are obstructed.
- The service brakes within the axle housing are damaged.
- Check the cable to the service brake pedals.
Problem 2
The rear service brakes for the high speed machine do not operate.
Probable causes
- Check the level of the hydraulic fluid in the brake system.
- Check for proper hydraulic fluid in the brake system.
- The lines to the rear service brakes are obstructed.
- The service brakes within the axle housing are damaged.
- Check the cable to the service brake pedals.
Problem 3
The service brakes slip.
Probable causes
- There is air in the hydraulic fluid that goes to the service brakes within the axle housing.
- The hydraulic oil additives in one of the axles or both axles is incorrect.
- The brake disc in the axle housing is worn.
- Hydrostatic braking may not be functioning. Check for the proper adjustment of the linkage to the inching valve.
Problem 4
The service brakes are not applied evenly.
Probable causes
- There is air in the hydraulic fluid that goes to the service brakes within the axle housing.
- The brake disc and associated components in the axle housing are excessively worn.
- The master cylinder is sticking.
Problem 5
Too much force needed to push the brake pedal.
Probable causes
- The brake pedals and/or brake pedal linkages are damaged.
- The master cylinder is sticking because of contaminated oil.
- The output pressure from the hydraulic pump is too low.
- The brake boost circuit of the master cylinder failed.
Parking Brake Problems
Problem 1
The parking brake does not hold the machine stationary.
Probable causes
- The parking brake must be adjusted.
- The brake linings are too worn.
- There is grease or oil on the brake drum and/or on the brake lining.
Problem 2
The parking brake does not engage when the parking brake control lever is actuated.
Probable causes
- The parking brake cable is disconnected.
- The parking brake cable has stretched until the cable will not actuate the parking brake.
- The parking brake is out of adjustment.