Steering Gear: Description and Operation

POWER STEERING GEAR

The power rack and pinion steering gear has a rotary control valve which directs hydraulic fluid corning from the hydraulic pump to one side or the other side of the rack piston. The integral rack piston is attached to the rack, and converts hydraulic pressure to a linear force which moves the rack left or right. The force is transmitted through the inner and outer tie rods to the steering knuckles.

If hydraulic assist is not available, manual control is still possible, but more steering effort is required. Without hydraulic assist, the movement of the steering wheel is transferred to the pinion. The pinion's movement is then transferred through the pinion teeth, which mesh with teeth on the rack, causing the rack to move.


MAGNASTEER(TM) POWER STEERING SYSTEM

The Magnasteer(TM) system is a speed-dependent power steering system. The system provides power assist at varying levels depending on need. A bi-directional magnetic rotary actuator in the steering gear adjusts the amount of torque (driver effort) necessary to turn the steering wheel. The EBCM or EBTCM, located at the lower left-hand front of the engine compartment, varies this torque by adjusting the current flow through the actuator. The amount of adjustment will be directly to wheel speed.

SEAL REPLACEMENT

Lip seals, which seal rotating shafts, require special treatment. They are used on the steering gear at the pinion shaft and on the pump drive shaft. When leakage occurs in these areas, always replace the seal after inspecting and thoroughly cleaning the sealing surface. If corrosion in the lip seal contact zone is slight, dean the surface of the shaft with crocus cloth. Replace the shaft only if very severe pitting is found, such that leakage cannot be stopped by cleaning the shaft.