GB860665A - Hydraulic ram and selector mechanism - Google Patents

Abstract

860,665. Hydraulic apparatus. TURNER MANUFACTURING CO. Ltd. Sept. 4, 1959 [Sept. 24, 1958], No. 30535/58. Class 69 (2). An hydraulic ram and selector mechanism comprises a hollow piston 4a in a cylinder 1 supplied with hydraulic fluid, and a hollow selector plunger 8 disposed within the piston and manually or otherwise controlled to vary its position within the piston to control a pair of fluid control valves 6, 7 exposed respectively to the pressure prevailing at opposite ends of the cylinder so as to cause the piston to move in one direction or the other until it reaches a position in which the valve previously opened by the selector plunger is closed. The selector plunger has cam surfaces 14, 15 which, when the plunger is moved relative to the piston, open one or other of the valves 6, 7. When the valve 6 is opened, fluid supplied from a pump or accumulator connected to an inlet 5b passes through the valve and a transfer port 25 to the right-hand side of the piston which is thus moved to the left relative to the cylinder and plunger until the valve is disengaged by the cam surface and the piston locked in position. When the valve 7 is opened, fluid in the righthand end of the cylinder flow through the valve and the hollow interior of the plunger or an outlet 18 until the valve is disengaged by the cam surface. The size of the valves and the profiles of the cam surfaces may be varied to provide different speeds for the forward and reverse strokes. The movement of the plunger may be controlled manually directly or by a cable 12 connected by a lever 11 to the plunger, the lever being spring-urged to a neutral position, by solenoids, or by pneumatic or hydraulic fluid at low pressure supplied to one side or the other of a piston connected to the plunger.