Steering

Steering is the term for the collection of components, linkages, etc. that allow a car or other vehicle to be turned to follow the desired course of its driver, except in the case of rail transport, where railroad tracks together with railroad switches provide this function.

The most conventional steering arrangement is to turn the front wheels using a hand-operated steering wheel, which is positioned just in front of the driver. Other arrangements are sometimes found on different types of vehicles, for example a tiller, or rear-wheel steering. Tracked vehicles usually employ differential steering - that is, the tracks are made to move at different speeds, or even in opposite directions, to bring about a change of course.

Recently, 4 wheel steering has gained popularity,especially in bigger cars and towing cars.All 4 wheels turn when you steer.There are options to switch off the rear steer,or steer only the rear wheel,independent of front wheels.At slow speeds,rear wheels turn opposite to front wheels and at high speeds,both front and rear wheels turn alike(electronically sensed).Turning radius is reduced 25%."Snaking effect" during motorway drives with a towing caravan is largely nullified.Honda had this as an option in their 80s PRELUDEs.But they were popular only in large farm vehicles and trucks.Now many large 4x4s have this option eg GM Sierra Denali uses "QUADRASTEER" made by Delphi.

Most modern cars use rack and pinion steering mechanisms. Older designs often use the recirculating ball type of mechanism, which is still found on trucks and utility vehicles, etc. In a rack and pinion design, the steering wheel turns the pinion via the steering column, which may use universal joints. The rack moves from side to side and applies torque to the kingpins of the steered wheels via tie rods and a short lever called the steering arm. Ackermann steering geometry is commonly used to allow each wheel to trace the correct path when travelling in a curve.

For safety reasons, all modern cars feature a collapsible steering column, which will collapse in the event of a heavy frontal impact to avoid excessive injuries to the driver. This safety feature first appeared on cars built by General Motors after an extensive and very public lobbying campaign by Ralph Nader.