GB528411A - Improvements in or relating to fluid pressure operated devices - Google Patents

Abstract

528,411. Fluid-pressure servomotors. MONOPOWER CORPORATION. May 6, 1939, No. 13556. Convention date, May 9, 1938. [Class 135] A fluid pressure operated device for displacing a machine part according to the back pressure built up in a fluid pressure system by a throttle valve controlled by a centrifugal governor has the throttle valve arranged to close against supply pump pressure and against elastic means on using centrifugal force. Fig. 1 shows a device for indicating the speed of a shaft 10 mounted in bearings 13 and driven by a belt 12 comprising a pressure gauge 24 connected by a pipe 22 to a manifold 20 surrounding the shaft. A second manifold 18 is connected to the outlet pipe 16 of a gear pump 15. The shaft has an axial passage 14 connecting three radial passages of which passages 17 and 19 lead to the manifolds 18 and 20 while the third passage leads to a leak-off port 28 in a disc 25 secured to the shaft 10. The leak-off port is controlled by a valve 30 loaded to open by a spring 33 and moved towards the closed position by centrifugal force acting on a straight or bent weighted lever 32 pivoted in lugs on the disc 25. The pressure delivered by the pump 15 is limited by a spring loaded relief valve 41 the load on which may be manually adjusted by means of a supplementary spring 47. Fig. 4 shows the invention applied to the control of a clutch comprising a pressure plate slidably keyed to a driven shaft 10B adapted to be moved against the action of a spring 57 into engagement with a friction disc 55 on the driven shaft 40. Pressure fluid from a pump 15B is admitted through an axial passage 14B in the shaft 10B to a chamber 60 behind a power piston 64, exhaust from-this chamber being by way of passages 27B, 28B controlled by valves 30B coupled together by a ring 67 to prevent jamming by centrifugal force. Flyweights 32B carried by bell-crank levers 75 carried by a member 62 mounted in the shaft 10B act through springs 63 on the ring 67 and bend with rising speed to move the valves against the action of springs 33B into their closed position. The load in the ring 67 is adjusted by spring arms 70 carried by a sliding sleeve 72 manually adjustable by a rod 74. In a modification the piston valves 30B are replaced by lift valves having discharge passages formed by flats on the valve spindles.