Abstract: A control valve (31) for a power steering system or the like has a sleeve (37) with a conical bore (52) and a rotor (47) with a conical outer surface (53) conjugate to the bore (52) for relative rotation therein. The conjugate surfaces of the sleeve (37) and rotor (47) are formed with longitudinal control grooves (54), (56), (57), (58) having bottom surfaces which are parallel to the axis of the valve (31), thereby allowing the sleeve (37) and rotor (47) to be formed in one piece molds and pulled straight out of the molds.

Abstract: The present invention discloses a power-steering pump which may reduce in a very stable manner the flow rate of the hydraulic liquid under pressure to be delivered to a power steering system with increase of the rotational speed of an engine beyond an idling speed and which may easily change the above rate reduction or attenuation characteristic depending upon the types of the automotive vehicles and power steering systems thereof. A flow-control valve which is disposed in parallel with the axis of a pump mechanism is provided with a variable-area orifice which determines the flow rate attenuation characteristic and which is defined by an orifice groove cut through a flange of a partition wall member and an enlarged-diameter portion at the free end of a control rod extended through the partition wall member from the front end of a control spool of the flow-control valve.