21st Century Overview - Steering

Steering enables the driver to control the direction of travel.   The driver turns the steering wheel, which carries the movement to the tie rods (steering linkage) attached to the steering-knuckle arms (steering arms), which pivot inward or outward, which moves the wheels and tires to the left or right.   There are two steering systems: linkage (worm gear) and rack-and-pinion.

Steering types: (A) recirculating ball (linkage, worm gear) and (B) rack-and-pinion.   The former uses a gear box to translate rotational into linear motion whereas the latter uses rack and pinion gears.

Four-Wheel Steering (4WS) uses a sterring shaft that carries the rotational motion of the steering wheel to the rear wheels.   At low speeds, the rear wheels turn in an opposite direction to the front wheels causing the car to turn more sharply with greater stability.   At high speeds, the rear wheels turn in the same direction as the front wheels to create more stability during lane changes.   4WS is most common on four-wheel drive and military vehicles.