| 摘要 |
PURPOSE: A device for opening and shutting a door of a bus is provided to hold a closed state of the door even if pressure in an air tank storing compressed air drops less than the shut-in pressure of the door by the leak of a piping by mounting a protection valve embedding a solenoid valve between a door cylinder and a speed regulating valve for opening and shutting, to release the valve in an emergency operation of the door and normally work, and accordingly to secure the locking safety of the door without mounting a mechanical locking device by guaranteeing constant pressure in the door cylinder even though the bus is kicked for a long time. CONSTITUTION: A device for opening and shutting a door(4) of a bus includes protection valves(10,20) embedding solenoid valves(11,21). The protection valves are mounted between a door cylinder(2) and speed regulating valves(7,8) for opening and shutting, respectively. The protection valve shuts off the flow of air from an air tank(1) to the door cylinder when pressure in the door cylinder drops below a reference pressure and electrically releases the flow of shut-off air in opening the door on emergency by operating an emergency door opening and shutting switch.
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