| 摘要 |
A hydraulic emergency braking system for a vehicle also having service brakes wherein a hydraulic directional control valve provides input pressure to a dump valve having a pressure outlet to spring apply, pressure-release brake actuators and a dumping outlet to the hydraulic reservoir. Internal conduits in the dump valve housing assure continuous transmission of inlet pressure to the pressure outlet thereby releasing the pressure-release brakes, while preventing reverse flow with a check valve when the directional control valve dumps the inlet pressure to the reservoir to apply the brakes. In the absence of inlet pressure to the dump valve, a spring-biased spool valve connects the pressure outlet to the dumping outlet, thereby immediately dropping the pressure in the brake actuators to the value predetermined by the spring. Orifices in the brake actuators then allow the pressure to gradually decay down to a point whereat nearly full braking force is applied, at which point the valve spool stops moving causing the pressure in the actuator to drop to zero giving full braking force.
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