In a rotary sliding vane pump having a non-circular cam ring which expands and contracts radially, a cheek plate is clamped against the end face of the cam ring and lies in rubbing contact with the rotor and vanes. The cheek plate has a wearing face of low friction material such as bronze. Unwanted wear between the cheek plate and the cam ring due to its expansion/contraction movements is reduced by the provision of one or more areas of hard metal adjacent the cam ring.
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.
A fluid powered vane motor for operation with a minimum of externally supplied lubrication has a motor chamber made up of a cylinder with an eccentric cylindrical bore and end plates abutting the ends of the cylinder. A rotor with a plurality of axially oriented radial slots on its circumferential surface is supported on bearing means within the chamber. Radially slidable vanes are disposed in the radial slots of the rotor so that they form a moving seal between the rotor surface and the cylinder wall. Pressurized fluid introduced to the motor chamber acts upon the vanes of the rotor and imparts rotary motion thereto. Operation with a limited amount of externally supplied lubrication is accomplished by making end plates of inherently lubricious material such as fiber-reinforced polymeric material, and by coating the innner bore of the cylinder with a soft coating having lubricious properties in contact with the selected vane material.
