Improvements in or relating to Fluid Pressure-Operated Jacks.

摘要

1,175,319. Fluid pressure step-by-step jacks. HOESCH MASCHINENFABRIK DEUTSCHLAND A.G. 4 Sept., 1968 [4 Nov., 1967], No. 42134/68. Heading B8J. A fluid pressure jack 10 arranged to operate with a stepped motion comprises a ram 15 slidable in a cylinder 14. A guide post 16 is set into base 141 of the cylinder 14 and its upper end forms a piston 161 dividing hollow chamber of the ram 15 into upper and lower chambers 151, 152, respectively. The guide post 16 has bores 162, 163 for the pressurized medium, the latter bore has a connection to cylinder chamber 142 through a bore 1411 in the base 141. The jack 10 rests on a movable carriage 11 which can be displaced by a drive unit 12, e.g. an hydraulic piston-cylinder device, mounted on a base-plate 13. The cylinder 14 has a releasable ring 17 secured to it, while a closure plate 18 covers the top of the ram 15. Both ring 17 and plate 18 have annular centring recesses 171, 181, respectively. When the pressure medium is introduced through bores 163, 1411 the jack 10 is fully extended as shown in Fig. 1. In this position load 19 on plate 18 is lifted sufficiently for a C-shaped support member 21 to be placed, by a rod 20, in position on ring 17, being centred by flange 212 mating with the recess 171, a plate 22 being centred on member 21 by a recessed portion 213. Ram 15 is then withdrawn, the load 19 being supported by the plate 22. With the jack 10 fully contracted, Fig. 3 (not shown), an annular ram extension member 23 with sealing plate 24 may be centred on the plate 18 and the load 19 raised by a further amount. This process is repeated until the load 19 has reached the desired height. The load 19 is lowered by reversing the above process.