Power Steering Pump: Description

The Saginaw Vane power steering pump is a constant displacement, vane operated pump with an integral oval shaped fluid reservoir. The power steering pump is connected to the steering gear by a pressure hose and return line.

Rectangular pumping vanes carried by a shaft driven rotor move the fluid from the intake to the cam ring pressure cavities. As the rotor begins to turn, centrifugal force through the vanes against the inside surface of the cam ring to pick up residual oil. This oil is then forced into the high pressure area. As more oil is picked up by the vanes, oil is forced into the cavities of the thrust plate through 2 crossover holes in the cam ring and pressure plate. The crossover holes empty into the high pressure area between the pressure plate and the housing end cover.

When the high pressure area is filled, oil flows under the vanes in the rotor slots, forcing the vanes to follow the inside oval surface of the cam ring. As the vanes reach the restricted area of the cam ring, oil is forced out from between the vanes creating high pressure. When the pressure exceeds set limits, the flow control pressure relief ball opens to relieve the pressure. Under normal conditions, the pressure requirements of the pump are below maximum, causing the pressure relief ball and the flow control valve to remain closed.