DESCRIPTION
The Saginaw power steering pump is a constant displacement, vane-type pump with an integral fluid reservoir. All models use vane-submerged type pumps. (Scheme 1)and (Scheme 2). The power steering pump of diesel models is incorporated into a vacuum/power steering pump assembly.
Scheme 1
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 (thrust plate on vane-nonsubmerged type).
Scheme 2
Filling the high pressure area causes oil to flow under the vanes in the rotor slots. The vanes are forced to follow the inside oval surface of cam ring. As the vanes rotate to the small area of the cam ring, oil is forced out from between the vanes, creating high pressure. When pressure exceeds set limits, the flow control valve opens and allows fluid to return to the inlet side of the pump.
Steering gear a variable ratio, recirculating ball type. Control valves are located inside steering gear housing.