Power Steering Pump: Description

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

Rectangular pumping vanes carried by a shaft driven rotor move the fluid from the intake to the cam ring pressure cavities. Centrifugal force positions the vanes against the inside surface of the cam ring. As the rotor turns, the vanes pick up residual fluid. Continued rotation of the rotor forces the fluid into a high pressure area.

As more fluid is picked up by the vanes, it 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, fluid flows is under the vanes, forcing them to follow the inside surface of the cam ring and effectively sealing pressure. As the vanes reach the restricted area of the cam ring, hydraulic pressure is produced.

When the pressure exceeds set limits, the flow control pressure relief valve opens and allows fluid to return to the inlet side of the pump. Under normal conditions the pressure relief and flow control valves are closed as the pressure requirements of the pump are below maximum.