GB1403658A - Multi-way valve actuated selectively by compressed-air or manually for the control of the working medium in hydraulic cylinders - Google Patents

Abstract

1403658 Fluid-pressure servomotor systems BERGWERKSVERBAND GmbH 26 June 1973 [10 July 1972] 30357/73 Heading G3P [Also in Division F2] A valve system controlling a double-acting hydraulic cylinder 3, e.g. for face support in mine workings, comprises a double-acting control piston 1.6 which is selectively movable manually by lever 1.7 or by compressed air supplied through inlet 1.16, the piston 1.6 carrying studs 1.4 acting on pilot valves 1.1 to control pressurization and relief of hydraulic pilot circuits acting on main valves controlling the flow to and from respective sides of cylinder 3. Each main valve comprises a doubleacting piston 2.1 subject on its lower face to pilot pressure in chamber 2.20 and co-operating on its upper face with a seat 2.6 to control the return flow from cylinder 3 via gap 2.7 and passage 2.22 to drain. Piston 2.1 slidably carries a further piston 2.3 having a body 2.2 co-operating with a seat 2.5 on piston 2.1 to control the high pressure flow from passage 2.11 and via bore 2.14 within piston 2.1 to cylinder 3. The main valve is biased downwardly by spring 2.17 assisted by a piston 2.8 slidable within body 2.2 and subject on its lower face to the high pressure flow communicated through passages 2.10 and 2.12. The face areas of the respective pistons are arranged such that when pilot pressure is supplied to chamber 2.20, gap 2.7 fully closes to cut-off drain flow from the respective side of cylinder 3 before body 2.2 moves off seat 2.5 to supply that side of the cylinder with high pressure. Each pilot circuit includes a drain passage 1.22 which is open when control piston 1.6 is in the neutral position shown but which is fully or substantially closed by stud 1.4 when the latter is moved to unseat pilot valve 1.1 and permit flow of pressure pilot liquid from inlet 1.11 to passage 1.13 leading via restriction 2.21 to main valve chamber 2.20. Control piston 1.6 is sealed by diaphragms 1.5 in a space 1.14 bounded by a casing 1 either secured to a casing 2 containing the main valves, as shown, or disposed remotely therefrom Fig. 11 (not shown).