Steering: Description and Operation

RACK & PINION GEAR

Fig. 1 Exploded View Of Steering Gear.:

DESCRIPTION


This power rack and pinion steering gear, Fig. 1 is a hydraulic-mechanical unit, using an integral piston and rack to provide power assisted steering control. Internal valve controls pump flow and pressure as required during operation. The unit consists of a rotary hydraulic control valve connected to the input shaft and a boost cylinder integral with the rack.

OPERATION


The rotary control valve utilizes the relative rotational motion of the input shaft and valve sleeve to control fluid flow. As the steering wheel is turned, the resistance of the wheels and weight of the vehicle cause a torsion bar to deflect, Fig. 1. This torsion bar deflection changes position of rotary valve and sleeve ports, thereby directing fluid under pressure to the proper end of the power cylinder. The pressure differential acting on the piston attached to the rack, provides the power assist.

The control valve is forced back to a centered position by the torsion bar when steering effort is removed. Pressure is then equalized on each side of the piston and the front wheels tend to return to a straight ahead position.