Power Steering Pump: Operation

Rectangular pumping vanes, carried by a shaft driven rotor, move fluid from intake to pressure cavities of the cam ring. As the rotor begins to rotate, centrifugal force throws the vanes against the inside surface of the cam ring to pick up residual oil, which is then forced into the high pressure area.

Oil is forced into cavities of the thrust plate and through 2 cross-over holes in the cam ring and pressure plate. This oil empties into the high pressure area between the pressure plate and housing end plate. Filling the high pressure area causes oil to flow under vanes in slots of rotor, forcing the vanes to follow the inside oval of cam ring oil is forced out from between the vanes, creating high pressure.