Description & Operation

Cherokee, Wrangler and 1998 Grand Cherokee steering gears are variable ratio, recirculating ball type units with rack piston and worm shaft. Power assist is provided by a belt driven hydraulic pump. Control valves are located inside steering gear housing. Steering gear for 1999 Grand Cherokee is rack piston/valve design.

Power steering pump is Saginaw vane-type. It provides hydraulic pressure for a recirculating ball type steering gear. Steering pump and reservoir are integral design. Manufacturer does not recommend overhaul of power steering pump. If service is required, pump must be replaced as an assembly.

Pump vanes are driven by a rotor and move fluid from the intake to the pressure cavities of pump ring. Centrifugal force moves vanes against inside surface of pump ring to pick up residual oil. As more oil is picked up, it is forced into cavities of thrust plate, into 2 crossover holes in pump ring and pressure plate, and into a high pressure area between pressure plate and housing end plate.

Filling the high pressure area causes oil to flow under the vanes in slots of the rotor. This forces vanes to follow inside oval surface of pump ring. As vanes rotate to small area of pump ring, oil is forced out from between vanes.