| Tools Needed | |
| 8T-0857 Pressure Gauge ( |
1 |
| 6V-9830 Cap | 1 |
| 6V-9509 Face Seal Plug | 1 |
An internal oil leak in the brake release system will cause the outlet pressure of the parking brake release pump to decrease. Leakage can also cause too much friction between the brake discs and the plates, which can damage these components when the machine is moving.
Note: If the machine is equipped with the Automatic Electronic Traction Aid (AETA) or the Traction Control System (TCS), it may be necessary to troubleshoot for leakage in the control valve for the AETA or for the TCS.
| NOTICE |
|---|
|
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. |
 |
|
Personal injury or death can result from machine movement. Place blocks in front of and behind the wheels to make sure the machine does not move while the parking brakes are disengaged. |
- Before completing this test, perform the Testing and Adjusting, "Parking Brake System Pressure - Test and Adjust". If the relief valve cannot be set, there is probably leakage in the brake release system.
- Remove the air from the brake release system. Perform the procedure for the Parking Brake in the Testing and Adjusting, "Brake System Air - Purge".
Show/hide table
Illustration 1 g00510588 Parking brake release hydraulic filter
(N) Pressure tap for parking and secondary brake.Show/hide table
Illustration 2 g00346868 Junction block for left rear parking brake
(M) Pressure tap for parking and secondary brake. - Use a coupler and a hose to connect a 8T-0857 Pressure Gauge (
0 to 10000 kPa (0 to 1450 psi) ) at pressure tap (N) or (M). - Start the engine. Operate the engine at low idle.
- Move the lever for the parking brake control to the OFF position.
- Operate the engine until the pressure stops increasing. Then, stop the engine.
- Record the pressure decrease in the first minute in Table 2.
Show/hide table
Table 2 Decrease In Pressure In The First Minute Plugged Wheel Pressure Decrease No plugged wheels Left Rear Right Rear Left Front Right Front - Apply the parking brake.
Show/hide table
Illustration 3 g00467508 (1) Oil line for the application of the parking and secondary brake release - Remove oil line (1) that is for the release of the parking brakes at one of the wheels.
- Cap oil line (1) with a 6V-9830 Cap. Plug the fitting on the wheel with a 6V-9509 Face Seal Plug.
- Start the engine. Operate the engine at low idle.
- Move the parking brake control to the OFF position.
- Operate the engine until the pressure stops increasing. Then, stop the engine.
- Record the pressure decrease in the first minute in Table 2.
- Apply the parking brake.
- Repeat Steps 9 through 15 for each wheel.
Note: Compare the data in Table 2 in order to determine the wheel that is leaking. If the oil pressure on the pressure gauge at pressure tap (N) or (M) has decreased
690 kPa (100 psi) or more in the first minute, the leak must be repaired. - If the oil pressure on the pressure gauge at pressure tap (N) or (M) has not decreased
690 kPa (100 psi) or more in the first minute, then the leakage is not severe enough to have an effect on the brake release system.Show/hide tablePersonal injury or death can result from air in the oil for the brake hydraulic system.
Air in the system can prevent complete brake application and it is possible that the wheels on the machine can not be stopped.
Air must not be in the oil for the brake hydraulic system to function properly.
- Remove the air from the brake release system. Perform the procedure for the Parking Brake in the Testing and Adjusting, "Brake System Air - Purge".
