| NOTICE |
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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. |
| Tools Needed | Qty |
| 8T-5320 Hydraulic Testing Group | 1 |
| 4C-4890 Hydraulic Test Group | 1 |
| 8T-0856 Pressure Gauge | 1 |
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| Illustration 1 | g00346868 |
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Location for pressure tap (M) | |
Note: The parking brake release pressure can be checked at location (M).
This test will show if the parking brake release pump section is working properly. This test will also show if the relief valve for the parking brake release system is set correctly.
- Remove the plug at location (M). Install a nipple at the location of the removed plug.
- With a coupler and a hose, install a 8T-0856 Pressure Gauge (
0 to 6000 kPa (0 to 870 psi) ) to the nipple. - While the parking brakes are activated, start the engine. Operate the engine at high idle rpm. The transmission should be in NEUTRAL. The pressure on the gauge must be at the relief valve setting. The relief valve setting is
4685 ± 100 kPa (680 ± 15 psi) .Show/hide table
Illustration 2 g00812537 Parking and secondary brake valve
(1) Cap
(2) Nut
(3) Relief valve for parking brake release system - If the setting of relief valve (3) for the parking brake release system is too low, perform the following procedure:
- Remove cap (1). Loosen nut (2).
- Turn the threaded rod clockwise in order to increase pressure. One turn increases the setting approximately
690 kPa (100 psi) .
- If the setting of relief valve (3) for the parking brake release system is too high, perform the following procedure:
- Remove cap (1). Loosen nut (2).
- Turn the threaded rod counterclockwise in order to decrease pressure. One turn decreases the setting approximately
690 kPa (100 psi) .
- Tighten nut (2). Replace cap (1).
- When you complete the test, stop the engine. Remove the test equipment.
Note: If the relief valve cannot be set, there is probably leakage in the brake release system. Perform the Air System and Brakes Systems Operation/Testing And Adjusting, "Parking and Secondary Brake Release System Leakage - Check".
