| TROUBLE |
STEP-BY-STEP PROCEDURE |
| Complete loss of pedal |
- Check clearance between brake lining and wheel.
- Check bleeder fluid level, bleeder solenoid operation and bleed system. If system has two stations bleed from both. If pedal is extremely light during bleeding on one-station system and fluid is not entering bleeder, replace control cylinder. On two-station system replace control cylinder, and if this does not improve operation check crossover valve and replace if necessary.
- If solenoid fails to function replace solenoid or pushbutton, or correct wiring fault.
- Inspect lines and units for leaks. Correct faults.
- Replace control cylinder or fluid reservoir bleeder. On two-station system, check crossover valve.
|
| Actuating cylinder stays extended (service brake will not release) |
- Open any tube connection near actuating cylinder.
- If actuating cylinder does not release, replace it.
- If actuating cylinder releases, replace control cylinder; on two-station system determine which should be replaced.
|
| Gradual loss of pedal during service application |
- Inspect lines and units for leaks.
- If repeated applications do not disclose visible leaks, replace control cylinder.
- If necessary, replace actuating cylinder.
|
| Parking brake does not stay released unless operator stands on pedal |
- If good signal lamp does not light when pressure switch closes, check wiring circuits and voltage, and check for leaks in hydraulic system.
- If lamp lights but brake will not stay released, check at brake control unit for open circuit in unit and for lack of power from switch.
|
| Parking brake stays released for short interval only |
- Power supply interruptions from collector rail breaks or other sources may need correction.
- Bleed system.
- Replace releasing cylinder and/or brake control unit.
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