Ford C-II Slipper-Vane Power Steering Pump & Valve

Driven on the left side of the serpentine belt loop is the Ford C-II power steering pump, housed inside a fiberglass-reinforced nylon fluid reservoir. Modeled down to its internal pumping cartridge, it contains a slotted rotor, ten spring-loaded metallic slipper vanes, an elliptical cam ring, bronze-faced pressure plates, and an internal flow-control and pressure-relief valve.

Double-Acting Elliptical Cam Ring: As the slotted rotor spins inside an oval-shaped cam ring, ten small metallic slippers pushed outward by tiny coil springs sweep along the cam contour. Because an ellipse has two wide lobbies and two narrow pinches per 360 degrees, every single revolution of the pump shaft draws fluid in twice and discharges high-pressure fluid twice—canceling radial bearing loads.

Why Steering Doesn’t Get Twitchy at 70 MPH: At highway RPM, the pump spins three times faster than at parking-lot idle. An internal spring-loaded spool valve senses pressure drop across an outlet orifice and bypasses excess flow internally so highway steering feel stays firm and stable.