| 摘要 |
A door closing piston-cylinder assembly which is designed to permit the door initially to move to closed position relatively rapidly but with controlled restraint until it approaches the fully closed position whereupon the door continues to move but considerably more slowly so that it will close smoothly and softly. The cylinder has a large diameter bore adjacent one end and a bore of smaller diameter adjacent the other end. A piston assembly has a first piston dimensioned to reciprocate in the large bore and a second piston of smaller diameter dimensioned to reciprocate in the smaller bore. The pistons have check valves which close when the pistons move in one direction and open when they move in the opposite direction. The smaller piston has a metering valve which is open at all times. A bleeder valve is provided in the end of the cylinder having the small bore. A coil spring is provided to move the pistons in a direction to close the door. The door closing piston-cylinder assembly is operable to control the opening and closing movements of a door relative to a door frame when the door is connected to the cylinder and the door frame is connected to the piston, or visa versa.
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