| 摘要 |
A parking brake system uses a pneumatically controlled brake actuator to provide both service and parking brake functions. The parking brake system for a vehicle includes a hand control that is manually movable between a plurality of operational positions. A valve is responsive to movement of the hand control and controls air flow from a parking brake air supply to the pneumatically controlled brake actuator. The valve includes a gate that defines the plurality of operational positions, which include a park position, a release position, and an off position. When the hand control is moved out of the off position and into the park position, the pneumatically controlled brake actuator remains pressurized and a latching mechanism is activated to mechanically lock the vehicle brake. When the hand control is moved to the release position, the vehicle brakes are re-applied to unload the latching mechanism. The parking brake system can be used on vehicles equipped with an electronic braking system, or can be used on vehicles that do not have an electronic braking system.
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