| 摘要 |
A locking device for a parking brake on a bus having air brakes prevents accidental release of the parking brake when a sensing switch indicates that the bus should not move (e.g., when the driver is absent from the driver's seat, or a passenger-access door is open). The locking device of the invention is affixed to a portion of the bus adjacent a parking brake air valve that has an air valve shaft moving along its axis between a fully extended position, in which the valve is in a brake-applied status, and a frilly retracted position in which the valve is in a brake-released status. The locking device has a locking arm moving between a locked position in which it prohibits the parking brake valve shaft from moving into the fully retracted position and an unlocked position in which it does not affect the motion of the valve shaft. Conventionally, the valve shaft has a knob on the end distal from the valve body, and the locking arm in the locked position, prevents the knob from being pushed in all the way. Because this arrangement does not require opening the brake lines, but instead merely limits the motion of an existing moving part, the locking device does not become part of the manufacturer's brake system, nor does it affect that system's certification to meet applicable motor vehicle safety standards.
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