The steering system in a vehicle is used to move the vehicle in a particular direction. This is a very important sub-system in a car without which it would be impossible for a vehicle to follow its desired path. The steering system can be used to steer all kinds of vehicles like cars, trucks, buses, trains, tanks etc.
The conventional steering system consisted of turning the front wheels in the desired direction. But now we have four wheel steering system mostly used in heavy vehicles, to reduce the turning radius, rear wheel steering system, differential steering system etc.
The basic components of any steering system are:-
1. Steering column
2. Steering box
3. Tie rods
4. Steering arms
The main geometry followed in steering is ACKERMANN STEERING GEOMETRY. It shows that while negotiating a curve, the inner wheel needs to follow a smaller path as compared to the outer wheel. This results in different steering angles for the respective tires.
STEERING RATIO is defined as the ratio of the turn of the steering wheel to the corresponding turn of the wheels, both which are measured in degrees. It plays an important role in determining the ease of steering. A higher ratio would mean that a large number of turns of the steering wheel is required to negotiate a small turn. A lower ratio would enable better handling. Sports cars usually have lower ratio while heavier vehicles have a higher steering ratio.
The Different types of steering systems are:-
1. Rack and pinion steering system
2. Recirculating Ball steering system
3. Power Steering
The Rack and Pinion steering system is the most common system found mostly in modern vehicles. It employs a simple mechanism. The parts of this system are steering column, pinion gear, rack gear, tie rods, kingpin. The circular motion of the steering wheel is transmitted to the pinion gear through the steering column and universal joint. The pinion is meshed with a rack which translates the circular motion into linear motion thus providing the necessary change in direction. It also provides a gear reduction, thus making it easier to turn the wheels. This system is preferred because of its compactness, efficiency, ease of operation. But at the same time it gets easily damaged on impact.
The Recirculation Ball steering system is employed in SUV’s and trucks. It uses a slightly different principle than the rack and pinion system. Here the motion is translated with the help of a recirculating ball gearbox, pitman arm and a track rod. It can transfer higher forces. But it is heavier and costlier than the rack and pinion system.
The Power steering system employs either one of the above systems and in addition has a hydraulic or electrical system connected to make it easier to steer. This helps in better control of the vehicle.
Other systems like steer-by-wire systems, drive-by-wire systems also exist, but they are not commercially used as of now but are most likely to replace the modern day steering systems in the future.