GB322507A - Improvements in or relating to lifting jacks - Google Patents

Abstract

322,507. Lake & Elliot, Ltd., and Rubury, J. M. Aug. 7, 1928. Jacks.-A fluid-pressure jack comprises a casing enclosing a reservoir and pump cylinders, the pump plungers being operated by means of a handle shaft which is rocked on its longitudinal axis to reciprocate the pump plungers by means of an angular boss and a sleeve mounted on the shaft and carrying plunger-engaging projections, the shaft being also capable of an axial movement to cause the angular boss to engage a release plunger to operate the lowering valve. The crutch 16 is carried by a screwed stem 15 mounted in the inner ram 12. The casing 1 encloses the ram cylinder 9, the reservoir 8 and the pump cylinders 26. The operating handle 7 has a shaft 6 having a universal joint connection 5 to an extension shaft 4 slidably and rotatably mounted in a boss 2 on the casing. The .shaft 4 has an angular boss 19 engaging jaws 22 on a rotatable sleeve 20 having pins 23 adapted to engage slots in the pump plungers 24, so that by rocking the shaft the pump plungers .are reciprocated to cause pressure fluid to be drawn from the reservoir through valved ports 28 and forced into the ram cylinder through valved ports 33, 37. To lower the load, the shaft 6 is slid inwardly, thus disengaging the angular boss from the sleeve and positioning it above a release plunger 40. By again rocking the shaft the release plunger is depressed so as to unseat a valve 38 and allow the prssure fluid to return to the reservoir through a port 42. A stop 43 is provided on the pump cylinder housing to allow the angular boss to be pressed against it to rock the jack bodily after lowering the load so as to cause a further lowering of the crutch to facilitate removal of the jack.