Abstract: A long-life, low maintenance, bi-directional vane-type water pump has a high degree of symmetry and operates with equal efficiency in either direction. The axial position of the drive shaft is controlled to permit improved lubrication by the pumping fluid of component parts on which the drive shaft is journaled.

Abstract: A variable displacement piston pump (10) including a plurality of axially aligned pumping cylinders (24) with a drive shaft (40) extending there between having a tiltable swash plate (30) disposed in a relatively dry cavity at one end of the drive shaft (40) for operating the pumping cylinders, and a reaction thrust plate (38) on the other end of the drive shaft (40), for providing reaction force in the drive shaft (40) opposite that provided by the swash plate (30). An inlet shaft seal (72) prevents fluid, which enters the pump at the inlet port (12), from filling the mounting housing (17) and submerging the mount shaft (44) portion of rotating assembly (16) and its supported swash plate (30). Two needle roller bearings (67) support the swash plate (30) and transmit torque from the drive coupling (19) to the swash plate (30). A high pressure fluid restrictor (70) meters hydraulic control fluid to the two needle bearings (67 ).