PRESSURE BALANCED BALL VALVE DEVICE

摘要

A ball valve is turned relative to its seat by means of three concentric sleeves mounted within a housing bore. Pins carried by the middle piston sleeve extend outward into slots in an outer carrier sleeve and inward into cam grooves in the outer wall of an inner drive sleeve. Axial movement of the middle sleeve under hydraulic pressure causes turning movement of the inner sleeve which then drives through bevel gears to turn the ball valve. The parts are construc-ted so that hydraulic forces within the housing acting to hold the ball valve in closed position against its seat are substantially balanced by forces in the op-posite direction acting against the outer sleeve.