GB1027339A - Improvements in or relating to fluid-powered linear actuators - Google Patents

Abstract

1,027,339. Fluid pressure apparatus. F. BRADBURY. Oct. 4, 1963 [July 6, 1962; July 1, 1963], Nos. 25996/62 and 26088/63. Heading F1P. An hydraulic or compressed air actuated piston 3, Fig. 2 (not shown) capable of initial advance at high speed and final advance at slow speed under load has a blind bore 7 lying on or parallel to the cylinder axis and opening into a cylinder space 11 and in which is slidably mounted a freely floating openended tubular probe 5 having its outer end capable of encircling a high pressure fluid inlet 22 in the cylinder end when the piston is retracted and the inner end of the probe 5 forms with the closed end of the bore 7 a pocket 9 to which pressure fluid passes from the inlet 22 to effect rapid advance of the piston under no load during which time low pressure fluid is entrained into the cylinder space 11; the slow advance of the piston 3 being initiated when high pressure built up in pocket 9 is transmitted through the annular space between the probe 5 and bore 7 to the cylinder space 11 to act on the whole area of the piston. This pressure build-up may also be transmitted through the tubular probe and through an orifice in the probe wall portion lying outside the piston bore 7. In a modification a double-acting piston has blind bores in opposite sides occupied by floating probes and in a further modification the device is telescopic as is the probe.