GB594595A - Hydraulic pressure generating apparatus - Google Patents

Abstract

594,595. Hydraulic apparatus. PAGE, H. E. March 20, 1945, No. 6992. Convention date, March 20, 1944. [Class 78(iii)] A hydraulic apparatus, in par ticular a jack, in which a work piston 11 in a main cylinder 25 is operated to execute its working stroke by pressure-generating means 36 (actuated by handle H) which forces fluid under pressure into the main cylinder, includes a spring 22 operably associated with the work piston to cause limited protractive movement thereof from the main cylinder. A compression spring 34 operable upon expansion to cause retractive movement of the work piston into its cylinder, and means operatively associated with said pressure - generating means to cause compression of said compression spring when said pressure - generating means forces fluid into the main cylinder, 25 to cause protractive movement of said work piston. Preferably rotatable valve 42 seated in bore 40, Figs. 1, 1A, distribute fluid drawn from reservoir R through port 37 by the motion of piston 36. past valve 54 and along port 58. Operating rod 44 controls valve 42 which has internal bores, 50, 51, 52, 53 and also bore 55 communicating at its inner end with longitudinal bore 56, and which has eccentric cam 62 capable of contacting stem 67a or 75a to unseatvalves 65, 67, Fig. 2, or 71, 75 respectively. With valve 42 in position as shown in. Fig. 5, oscillation of pump piston 36 produces merely a circular flow of fluid from reservoir R via port 37, valve 54, port 58, bores 55 and 56, and port 57, back to the reservoir. A twist of rod 44 moves valve 42 into the position as shown in Fig. 6 in which position fluid driven by pump passes through port 58, bore 50, bore 52, port 81, Fig. 2, from whence it divides, part to pass along port 84 to build up pressure in surge chamber 33 and port to pass valve 71 and along port 72 to build up pressure in chamber 33 and part to pass valve 71 16 and connecting-rod 26 to actuate lifting arm 8. At the same time cam 62 presses upon stem 67a to unseat valves 65, 67 and to allow the initial pressure in annular chamber 25 to be released, the fluid flowing back via port 87, valves 65 and 67, and port 57 to the reservoir, thus permitting compressed spring 22 to be released and to give an initial movement to work piston 16 so that the work may be contacted, the raising of the work being effected by hydraulic pressure. A further twist of rod 44 moves valve 42 to the position as shown in Fig. 7. Cam 62 contacting stem 75a unseats valves 71, 72 to allow fluid compressed in chamber 30 to pass to port 57 back to the reservoir. Compressed fluid in surge chamber 33 is forced by plunger 32 through port 88, bore 52, bore 53, port 80, valve 65 and port 87 to annular chamber 25 so that spring 22 is compressed and the work piston 16 retracted. Finally, employment of pump 36 may force fluid into annular chamber 25 so as to compress spring 22 further and to bring arm 8 to full down position. Specification 594,586 is referred to..