Abstract: In a cam ring of a vane pump having a contoured bore whole wall is constantly and slidingly engaged by the radially outermost ends of vanes during rotation of a rotor, a radially inner part of the cam ring including the wall of the contoured bore is formed of sintered alloy while a radially outer part surrounding the inner part is formed of a material which prevents working fluid from oozing out therethrough. The outer part comprises a moulding of plastics, a die casting or a piece blanked from a steel sheet.

Abstract: A vane pump driven by an engine to serve generally as a source of hydraulic fluid pressure for operating a power steering apparatus.A high pressure chamber (13) is formed either in a pump housing (4) or in a cover plate (6) by casting using a core. An end of the pump housing (4) or of the cover plate (6) defines a slide surface (11) with which a rotor (2) and vanes (1) are slidably and directly engaged, thus being formed with delivery ports (12) or suction ports (29). This precludes the need of a side plate, a spring for biasing the side plate against the rotor, and others which have hitherto been indispensable for a vane pump, so that the total number of components parts is reduced.A cam ring (5) is sandwiched between the pump housing (4) and cover plate (6) and locked together to the pump housing (4). This makes it needless to form a bore in the pump housing (4) for accommodating a cam ring and thereby enhances the machinability of such a pump.