GB1209306A - Improvements in or relating to linear hydraulic motors - Google Patents

Abstract

1,209,306. Hydraulic reciprocating motors. NATIONAL RESEARCH DEVELOPMENT CORP. Dec.14, 1967 [Dec. 19, 1966], No.56784/66. Heading F1A. Linear movement of a ram 242 Fig. 9 relative to a fixed body 200 is effected by abutment of a plurality of longitudinally spaced continuously reciprocating pistons 224, 226 --- 238 against an undulating cam surface 240 extending along the ram when hydraulic fluid delivered by a pump 263 Fig.7 through a directional control valve 265 is selectively supplied to pairs of cylinders e. g. 204, 210, and 206, 208 through two-position spool valves only two of which 252, 254 are shown and which spool valves are controlled by a sensor device 256 comprising a fluid discharge nozzle 276 connected to the pump 264 through a reducing valve 258 and connected by a branch line 268 to one end of spool valve 252 and a similar nozzle 278 connected by a branch line 270 to one end of spool valve 254, the arrangement being that each nozzle is periodically blocked by spaced lands 274 on the ram surface and periodically relieved when in register with recesses 272 between said lands resulting in pressure pulses being sent through lines 268, 270 to move the associated spool valve to its other position. In the valve positions shown in Fig. 7 cylinders 204, 210 are pressurized whilst cylinders 206, 208 are connected to exhaust. Each of the cylinders 204, 206 --- 218 is one of a group of 16 radial cylinders. In a modification the cam surface remains fixed and the cylinder block is moved longitudinally and the spool valves are actuated by compressed air pulses generated when the nozzles are blocked.