| 摘要 |
<p>A disc brake is disclosed which has a spring actuator in addition to the usual hydraulic actuation. When the brake is functioning normally, fluid pressure opposes the spring actuator to permit normal hydraulic operation of the brake. However, when fluid pressure is not available to the brake, because of a malfunction or because the vehicle operator has closed a valve to isolate the brakes from the vehicle's hydraulic system, the spring actuator maintains the frictional elements engaged with the rotor. The spring actuator, therefore, functions as both a parking brake and a fail-safe brake that immobilizes the vehicle when a malfunction in the vehicle's hydraulic system occurs. Mechanical release means are provided to release the spring actuator to permit the vehicle to be moved if the spring actuator has applied the brake while the vehicle is standing in an inconvenient location.</p> |
