Steering Gear: Description and Operation

DESCRIPTION






The steering gear on this vehicle is a rack and pinion unit with power assist. It is mounted on the front suspension crossmember. The steering column connects to the steering gear shaft on top of the gear. The outer tie rod ends of the gear connect to each suspension steering knuckle to steer the vehicle.











Depending on the vehicle production date, the vehicle could use one of two power steering gears. There is an early production steering gear and a later production gear. Externally, the power steering gears appear the same. Without a parts book, the easiest way to identify whether your car is equipped with an early or later production steering gear is to identify what type of steering column intermediate shaft the vehicle has. Early models use a intermediate shaft with a slap coupler connection at the steering gear pinion shaft. Later models use a slider-stage style intermediate shaft.






An easy way to identify an isolated steering gear is to look at the very end of the pinion shaft. Early models have 2 parallel flats on the end where the steering column intermediate shaft would bolt up. Later models have 2 flats that are at 60 degree angles to one another where the steering column intermediate shaft would bolt up.

OPERATION
Turning of the steering wheel is converted into linear travel through the meshing of the helical pinion teeth with the rack teeth. Power assist steering is provided by an open center, rotary type control valve which directs fluid from the pump to either side of the integral rack piston.
Road feel is controlled by the diameter of a torsion bar which initially steers the vehicle. This movement directs fluid behind the integral rack piston, which, in turn, builds up hydraulic pressure and assists in the turning effort.
The drive tangs on the gear pinion mate loosely with a stub shaft. This is to permit manual steering control to be maintained if the drive belt on the power steering pump should break. However, under these conditions, steering effort will be increased.