| 摘要 |
1,193,229. Pneumatic jacks. KLAUS ESSER K.G. 18 July, 1968 [18 July, 1967], No. 34353/68. Heading B8J. In a double-acting pneumatic jack for opening and closing and for varying the degree of opening of cover members, such as windows or light domes, chamber 4 is divided by a wall 6 to form a chamber 12 containing an auxiliary piston 7 and a pair of spring-loaded tilting look-plates 14, 15 which, in the rest position shown, hold pistontod 1 against movement in either direction. The plates 14, 15 are engaged by one end of a forked arm 17, the other end of which is secured to a fixed point 16. Cylinder 3 is pivotally secured to the point 16 by a lever arm 18 pivoted to the cylinder 3, which arrangement permits slight axial movement of the cylinder 3 with respect to the arm 17. In order to extend the rod 1 compressed air is supplied through conduit 19. The rod 1 being locked, pressure in chamber 5 moves the cylinder 3 downwards until the piston 7 is engaged by the end of the cylinder 3 and moved with the cylinder 3 to disengage the lock plate 14, Fig. 2 (not shown). The rod 1 is then free to move upwards to a desired position. At this position the air pressure in conduit 19 is reduced and the chamber 5 is discharged via high-speed vent valve 20. The weight of the rod 1 then causes it slightly to reverse its movement thereby angling the plate 15 to lock the rod 1. To retract the rod 1 from the rest position compressed air is supplied through conduit 8 forcing the piston 7 down to unlock plate 14 and uncover branch conduit 11. Build-up of pressure in the chamber 4 lifts the cylinder 3 to unlock the plate 15, Fig. 3 (not shown), whereupon the rod 1 is retracted by the continuing supply of compressed air to the chamber 4. At the desired position the air pressure in the conduit 8 is reduced whereupon high-speed vent valve 21 opens so that the cylinder 3 can move downwardly removing from the plate 15 the support of the wall 6 and the plate 15 again locks the rod 1. Several jacks may be interconnected for synchronous movement (not shown). |
