STEERING
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.
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