GB475795A - Improvements in or relating to lifting jacks - Google Patents

Abstract

475,795. Lifting - jacks. SESSIONS, D. W., and SESSIONS & CO., Ltd., D. May 22, 1936, No. 14447. [Class 78 (iii)] A hydraulic lifting-jack comprises a cylinder 12 having a pump and valve casing fixed on its upper end, and a reservoir 31 fixed on the upper end of the pump casing, a piston carrying a ground-engaging foot being adapted to be displaced downwardly in the cylinder and so cause the vehicle-engaging attachment 63 fixed to the cylinder to raise the vehicle. By removing the detachable handle 46 from a supporting clip on the cylinder and applying it to the member 44 to operate the pump piston 39, liquid is drawn from the reservoir through the valve 33 on the outstroke, and forced past the valve 34 into the cylinder on the instroke. A spring-controlled plug valve 52 can be released by unscrewing the member 53 to byepass the liquid through ports 51, 49 back to the reservoir for lowering. Both valves 33 and 34 are spring-controlled and both pistons have double V-shaped packing rings 24, 25 facing in opposite directions. Ports 26, 27 admit pressure fluid to these packings. An annular ledge on the piston engages an internal projection 19 at the base of the cylinder to limit the maximum lift. A filling hole (not shown), is provided in the pump casing for charging the inverted reservoir which also serves as an indicator to secure that the correct amount of fluid is supplied to prevent too great a vacuum during working. A feature of the construction is that no operating parts or members pass through the wall of the reservoir. Specification 475,796, [Group XXVI], is referred to.