Auto questions: how car steering works

A plain description of how steering systems work in cars today and why they have two separate ways to do it.

Steering systems have been around just about as long as the wheel. Without steering you would move, but wouldn't have any choice of destination.

In today’s' automotive world there are two different but related types of steering systems. The first one is the 'Steering gear' system.

Starting at the most familiar place, the steering wheel, attaches a long splined shaft that goes down into the steering column and exits through the floor above the accelerator and brake pedals. This shafts only job is to rotate in place along with the steering wheel. The rotating shaft goes into the steering box housing, which is bolted directly to the frame of the car itself. The shaft ends at a small gear inside the box that contacts and meshes with another gear at a 90 degree angle. Being driven by the first gear, the second gear exits the steering box as a shaft that twists in unison with the first shaft.

At the end of the second shaft mounts an arm that swings in the radius of the shaft, similar to the shoulder joint in consideration of your arm moving back and forth in a horizontal plane.
The end of that arm attaches to a long bar that sits perpendicular to the front/back line of the car and ends near the front wheels of the vehicle. At each end of the bar is attached a 'Tie Rod'. These tie rods then attach to the actual wheel spindles themselves and push or pull the wheels in either direction with the center bar. The tie rod ends are pivotable at each end in order to allow vertical movement of the suspension, or bouncing that a vehicle endures during road travel.

Bulky and heavy overall with multiple moving parts most manufacturers have moved onto using the 'Ract and Pinion' steering system (often mispronounced as "Rack and Pinion") for smaller cars, trucks and SUVs.

The steering wheel and first shafts are the same for the ract and pinion. The difference in ract and pinion systems if that the shaft goes directly into a housing that either bolts to the frame or mounts on the body of the vehicle. The housing of the ract and pinion is long and narrow compared the actual box shape of the steering gear. The second gear inside the housing is replaced by a center bar similar to the bar outside the steering box, but this bar has teeth in it to mesh with the gear of the first shaft. Basically, it's like a gear that's been unfolded into a long flat surface.

This toothed bar then goes toward each wheel and is attached to tie rods at each end. From there, the tie rods connect to the wheels and pull or push the wheels in either direction as dictated by the center bar.

Ract and pinion steering is lighter, self contained and has fewer moving parts than the conventional steering gear system but is far weaker than the conventional steering. This is why most heavy duty trucks still use the 'box' set ups today.

Tie rods are multiple piece units. Depending on application a tie rod can be either 2 or 3 pieces. An inner tie rod end, an adjustable sleeve, and an outer tie rod end. Some cars eliminated the adjustment sleeve by putting the adjustable threads on the tie rod ends themselves.