| 摘要 |
PURPOSE: A system for opening and shutting a middle door of a bus is provided to widen an entrance, to improve durability and to simply install an external appearance by making the middle door as two-way folding door, connecting a pneumatic cylinder to the hinge portion of the door, connecting the pneumatic cylinder to a speed control valve, a magnetic valve, an anti-shock valve, and an emergency valve through a hydraulic line, and folding the middle door in both sides using pneumatic pressure. CONSTITUTION: Middle doors(11,11') of a bus are folded in both sides and pneumatic cylinders(13,13') are connected to hinge portions(12,12') of the doors. Then, the pneumatic cylinders are connected to many speed control valves(14), magnetic valves(15,15'), an anti-shock valve(16) and an emergency valve(17) through a hydraulic line(18) to be eventually connected to an air supply(20). The air supply is connected to a control switch(19). When the control switch is turned on, pneumatic pressure is transmitted to the pneumatic cylinders and pistons in the cylinders are pulled with pneumatic pressure to open the doors. When the control switch is turned off, the pistons are pushed with pneumatic pressure to close the doors.
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