GB635710A - Hydraulic motors or jacks incorporating locking and pressure release mechanism - Google Patents

Abstract

635,710. Hydraulic jacks. ELECTROL, Inc. Feb. 18, 1947, No. 4719. Convention date, Feb. 25, 1946. [Class 69 (ii)] [Also in Group XXX] A hydraulic motor or jack comprises a piston in a cylinder with cooperating locking members on the piston and the cylinder for locking the piston at one end or at either end of the cylinder, in which at one end or at each end of the cylinder adjacent to the locking member on the cylinder, a normally closed valve is interposed between an outlet port and the pressure supply, and an operating member for the valve is so disposed that, when the locking members of the piston and the cylinder coact, the valve-operating member is engaged by the piston and actuated to open the valve so as to relieve the pressure acting on the piston. The locking is effected by a projection 40 on a spring-loaded locking member 34 or 35 engaging the piston 20 and forcing balls 26 or 27 into a recess 33 or 30 in the cylinder 10. In order to supply pressure to move the piston, two end caps 11 and 12 have inlet and discharge ports. A port 46 may be connected through a selector valve to a pressure source and a port 49 to a return line for the system. A flange 38 is positioned between the end of the cap 12 and the port 47, and flanges 36, 37, disposed on opposite sides of the port 49 to prevent direct communication between port 49 and ports 46, 47, but permitting liquid to be introduced into the cylinder 10 between the piston 20 and the locking member 34. The port 52 is connected to a return line and the port 51 (not shown) through the selector valve to a pressure source and port 47. Port 50 (not shown) is connected to port 46. A valve 56 in the looking piston extends beyond the projection 40 when the valve is sealed. When the locking member 34 is moved to the left by the piston 20, the valve 56 is unseated and connects the ports 47 and 49. Since the port 47 is connected to the pressure port 51 and the port 49 to the return line, the liquid is byepassed from the interior of the cylinder 10 to the return line, hence relieving the pressure on the piston 20. Unlocking is effected when liquid admitted through the port 46 urges the piston 20 and the locking member 34 apart, whereby the balls are released inwardly and the piston 20 forced to the opposite end of the cylinder. In a modification, Fig. 6, the locking means are fitted to one end of the device only and a tubular pistonrod 81 slidable within and relative to the piston 77, is fixed to the end cap 71 and has a second piston 86 and piston-rod 85, slidable within itself and extending through the cap for attachment to a weight to be lifted.