Steering

Steering is the term applied to the collection of components, linkages, and etc. that allows for a car or other vehicle to follow a course determined by its driver. Except in the case of rail transport in which railroad tracks combined together with railroad switches provide the steering function.

Table of contents

1 Introduction 2 Four Wheel Drive 3 Rack and Pinion 4 Safety

Introduction

The most conventional steering arrangement is to turn the front wheels using a hand-operated steering wheel which is positioned 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 such as tanks 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.

Four Wheel Drive

Recently, four wheel drive steering has gained popularity especially in bigger cars used for towing. All four wheels turn at the same time when you steer. There are options to switch off the rear steer and options to steer only the rear wheel independent of the front wheels. At slow speeds the rear wheels turn opposite of the front wheels, and at high speeds both front and rear wheels turn alike (electronically sensed). The turning radius in four wheel drives is reduced by 25%. The "Snaking effect" experienced during motorway drives with a towing caravan is largely nullified. Honda had this as an option in their 1980's Preludes, but they were more popular in large farm vehicles and trucks. Now many large 4x4's have this option such as GM's Sierra Denali which uses "QUADRASTEER" made by Delphi.

Rack and Pinion

Most modern cars use rack and pinion steering mechanisms. Older designs often use the recirculating ball mechanism, which is still found on trucks and utility vehicles. 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.

Safety

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 enacted by Ralph Nader.