| 摘要 |
<p>384,552. Door-operating appliances. NATIONAL PNEUMATIC CO., 420, Lexing- ton Avenue, New York, U.S.A. May 11, 1932, No. 13613. Convention date, Dec. 29, 1931. [Class 65 (i).] A fluid-pressure engine, more especially for operating vehicle doors and the like, comprises a cylinder 1 closed at both ends by caps 2, and containing a pair of pistons 12, 15, connected by a hollow rod 13. Rods 25, 26 are slidably mounted on the pistons to engage each a check valve and cushion the movement towards the ends of the strokes. The cylinder caps 2 carry bored extensions 4 for connection by pipes with a valve adapted in one position to place the opposite ends of the cylinder under vacuum and atmospheric pressure respectively, and, in another position, to reverse these pressures to actuate the door-operating mechanism or the like which is connected to a bracket 20 carried by a sleeve 17 on the rod 13. Each extension 4 has a ball check valve 8 adapted to seat, under pressure, against a ring 6. Grooves 10 and a small pressure byepass passage 14 to prevent stalling are formed in the walls of the extensions 4. Springs 27, 28 are held between a pin 22 carried by the piston-rod 13 and shoulders on the outer ends of the rods 25, 26 so that, as the pistons move towards the ends of their strokes, one rod opens the corresponding check valve 8 and its spring is compressed. Return movement of the piston, on operation of the control valve mentioned above, results in this spring being gradually released and compression of the opposite spring, when the opposite rod engages its check valve and the piston is slowed down.</p> |
