CHANGEOVER VALVE UNIT FOR POWER-ASSISTED STEERING SYSTEMS

摘要

A changeover valve unit for a power-assisted steering system includes input and output shafts arranged for relative rotation on aligned axes, a spool valve element concentrically assembled with the input shaft to be axially shifted in response to relative rotation of the shafts, and a sleeve-like valve casing surrounding the spool valve element to cooperate with the spool valve element for controlling the supply of fluid under pressure to a hydraulic cylinder associated with the steering system. A thrust plate is rotatably coupled at its inner periphery with the output shaft and secured at its outer periphery to the valve casing thereby to prevent rotation of the valve casing and to permit axial movement of the valve casing caused by displacement of the output shaft.