| 摘要 |
The hydraulic and electric powered parking brake system (10) comprises a redundant or simultaneous operation of the system (10) to meet Federal Safety Standards. A dash mounted control knob (24) operates a hydraulic brake application mechanism (20) which transmits a hydraulic pressure to a hydraulically operated pilot piston (70). The control knob (24) also operates a switch (30) to send an electrical signal to an electrical control unit (100) which sends an electrical signal to a solenoid (80). The solenoid (80) and hydraulic pilot piston (70) can be operated, independently or simultaneously, to displace a control valve (60) located within a parking actuator assembly (114) and effect the release of hydraulic pressure from spring apply and hydraulic release actuators (16, 90) connected to vehicle brakes (18). The hydraulic fluid is released past the control valve (60) and to a reservoir (52). When the parking brake knob (24) is returned to an at-rest position, either the solenoid (80) or the hydraulic pilot piston (70), independently or simultaneously, can be operated to effect closing of the control valve (60) and actuation of a motor pump (50) which transmits fluid pressure to the spring apply and hydraulic release actuators (16, 90) so that the actuators will release the vehicle brakes (18) connected therewith.
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