| 摘要 |
<p>1,082,715. Hydraulic jacks. TECALEMIT (ENGINEERING) Ltd. Oct. 16, 1964 [Oct. 16, 1963], No. 42300/64. Heading B8J. A security device for a lift (not shown) mounted on a piston 3 sliding in a guide 2 in a cylinder 1 of a carrier jack locks the piston 3 by the wedging of rollers 7 between the piston 3 and the frusto-conical bore 10 of a locking ring 6. The action of the device is controlled by a control jack 9 connected to the control member of the carrier jack. When fluid pressure is applied to the cylinder of the control jack 9 an unlocking ring 8 with a rim 19 pivots at 17 and lifts the rollers 7 away from contact with the piston 3 so that the piston 3 is free to move. So that a slight leak in the carrier jack and consequent descent does not impair the operation of the control jack 9 the locking ring 6 is carried by springs 15 sufficient to carry the weight of the ring 6 so that although the rollers are in jamming position the jamming effect is less than the force of the springs 15. In an oleo-pneumatic system a small aperture 28 delays retraction of the control jack 9 when the look is applied to allow for the delay relatively to the operation of the control member. In an hydraulic system immediate purging of the control jack 9 is provided. The rollers 7 are solids of revolution the ends of each of which are convexly radiused to match the frustoconical bore 10, while the middle part is concavely radiused to match the piston 3. The sum of the lengths of the convex parts is equal to the length of the concave part of the roller 7. When applied to a non-vertical jack the rollers 7 are retained in a cage permanently urged by resilient means to bring the rollers 7 into contact with the piston 3 and the frusto-conical bore 10. The control jack 9 in such a case is arranged to overcome the resilient means to unlock the device.</p> |
