Abstract: A vane cell pump comprises a housing having a small bore at one end extending to a large bore at the other end. A drive shaft for a pump package, i.e., a rotor, vanes and cam ring in said large bore. The other end of the housing is closed by a pressure plate against which one radial face of the pump package rotates, and which pressure plate is bolted to the housing. Another pressure plate within the large bore is pressed against the opposite radial face of the pump package by being exposed to an outlet pressure chamber of the pump. The area of the outlet pressure chamber to which the latter pressure plate is exposed is demarcated by axial sealing elements surrounding the drive shaft and exerting a compression force between a housing wall and the latter pressure plate. The construction effects a tight tolerance between relatively moving parts at all times including the start of pump operation.

Abstract: A rotary vane pump has a pressure operated valve to bypass pump outlet flow to the inlet of the pump for flow regulation. A metering throttle bore, downstream of a choke bore, responsive to viscosity is a passage from the pump to a consumer such as a servosteering system. Responsiveness to viscosity is effected by providing an area in cross section for flow passage in the metering bore, which flow area is much smaller than the wetted surface area of the passage. A pressure agent at a cold temperature having greater viscosity than that at a higher temperature will effect flow regulation of the pump sooner than the high temperature pressure agent. Since for a cold pressure agent the viscosity is higher, the resistance to flow through the metering throttle bore is greater. As a result, the pump must work at a higher pressure which actuates the pressure operated valve to effect bypass flow.