| 摘要 |
<p>The vehicle is provided with a pair of spring applied brakes which are individually controllable through hydraulic actuators acting in opposition to the springs. The brakes are individually controlled by a valve associated with the hydraulic actuators and are automatically, simultaneously applied by operation of brake pressure regulating valves which are biased by the pressure of the hydraulic control system for the forward-reverse clutches of the vehicle transmission. The vehicle brakes are applied by balancing pressure across the piston of the brake actuator. During forward or reverse travel of the vehicle, the pressure on one side of the brake actuator compresses the spring to release the brakes. When low fluid pressure is supplied as when the engine is dead, the brake actuator pressure will drop thereby permitting the springs to apply the brakes. When the engine is running and the hydraulic systems are functioning normally, the brakes are applied by the springs whenever the pressure is balanced on opposite sides of the spring loaded brake actuator. The brake pressure regulator valves cause the pressure to be balanced at reservoir pressure when the biasing pressure from the change speed transmission control drops to a low level as when in neutral or during directional shifts.</p> |
