| 摘要 |
A spring-applied, pressure-released parking brake is controlled by an electrohydraulic control system. A solenoid operated parking brake control valve and a manually operated tow control valve control communication between the engine driven pump, the sump, the operator driven pump and the release chamber of the parking brake so that the parking brake can be released and applied during normal operation of the engine driven pump and so that the parking brake can be released by operation of the operator driven pump when the vehicle is shut down. A transport sump valve and an inlet check valve operate to prevent the parking brake from engaging while the vehicle is moving too fast, as a result of operator error, hydraulic failure or electrical failure.
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