Abstract: A steering power-assistance pump of vane type includes a combined flow control and pressure relief valve. When the steering valve of the steering arrangement shuts off the flow of oil, the output of the pump is converted into heat within the pump which accordingly suffers a substantial rise in temperature. The rotor of the pump and the cam ring with which the rotor vanes co-operate are combined with a pressure plate and a wear plate on respective sides of the rotor to form a unit which is displaceable in the axial direction of the pump against the force of a compressible sealing means for sealing off inlet ducts relative to a pressure chamber behind the pressure plate. The unit is thus displaced against the force of the compressible sealing means, as a result of thermally induced deformation of the housing portions of the pump. The wear and pressure plates have coatings of bearing metal on their surfaces which co-operate with the rotor, to provide better anti-friction properties.

Abstract: A hydraulic pump with a falling characteristic curve in respect of the output flow relative to the pump speed. A flow control valve (40) has a spool (41) with a hollow (50) extension portion (49), and an annular chamber (52) with two control edges (53, 56) which co-operate with the valve output duct (38) and a relief duct (19) to form restrictor means which are in opposition to each other. The valve output duct (38) and the relief duct (19) are disposed substantially radially with respect to the spool.

Abstract: A hydraulic rotary vane pump comprises a flow control valve with a venturi throat disposed upstream thereof whereby the entire delivery flow from the pump passes through the venturi throat. The flow control valve is operable to control the amount of fluid flowing to the delivery outlet of the unit, under the influence of the pressure drop at a restrictor throttle in the form of a bore extending from the throat transversely with respect to the axis thereof. The angle between the axis of the venturi throat and the axis of the bore is between 90.degree. and 150.degree. depending on the degree to which the characteristic of the outlet flow produced is intended to drop off.

Abstract: A steering assistance pump includes a temperature sensor valve which communicates with an inlet duct of the pump by way of an additional, normally closed outlet passage. When a pressure relief valve responds, upon blocking of the servo steering means, the temperature of the hydraulic fluid in the system increases to such a degree that it exceeds the limit value of the temperature sensor valve. The valve thus opens to cause the pilot control pressure in the control chamber of the pressure relief valve to be reduced, whereby the pump pressure itself is also reduced.

Abstract: In a rotary vane pump having a normally vertical suction feed flow passage (17a, 17b) which opens tangentially into a horizontal, elbow-bent feed passage (18a, 18b) and a discharge passage (19a, 19b), the direction-changing portion is formed by a plug-like insert (51) which is pressed into a stepped bore (61). The insert (51) comprises erosion-resistant material.