Why does your car need a suspension system? Well, imagine yourself driving a skateboard and feeling every bump and pothole because the skateboard has direct contact with the road. That’s what suspension prevents from happening.

A bit of history

In the olden days of wagons and carriages, people tried to solve the problem of a bumpy ride by slinging the carriage body from leather straps attached to four posts of a chassis that looked like an upturned table. Because the carriage body was suspended from the chassis, the system came to be known as a “suspension”.

Components of a suspension system

The suspension acts as a “bridge” between the occupants of the vehicle and the road, and is part of the chassis. The fundamental components of any suspension system are the springs, shock absorbers and anti-sway bars.

Springs

When a car’s wheel goes over a bump, the spring absorbs that additional load and keeps the road shock from reaching the chassis. This ensures that the tyre maintains contact with the road. There are three types of springs:

• Coil springs: The most common type. Coil springs compress and expand to absorb the motion of the wheels and are a component in both strut and conventional suspension systems.



• Leaf springs: This type of spring consists of several layers of metal (called “leaves”) bound together to act as a single unit. They are found mostly on heavy-duty vehicles.



• Torsion bars: These use the twisting properties of a steel bar to provide coil-spring-like performance. One end of the bar is anchored to the vehicle frame while the other is attached to a wishbone, which acts like a lever that moves perpendicular to the torsion bar.

Springs by themselves can’t provide a perfectly smooth ride because while they are great at absorbing energy, they are not so good at dissipating it.

Shock absorbers

Shock absorbers control the unwanted spring motion through a process known as dampening so that shock isn’t transmitted to the car chassis. They dampen the vertical motion induced by driving on a rough surface by turning the kinetic energy of suspension movement into heat energy that can be dissipated through hydraulic fluid.

All modern shock absorbers are velocity-sensitive – the faster the suspension moves, the more resistance the shock absorber provides. This enables shock absorbers to adjust to road conditions and control all of the unwanted motions that can occur in a moving vehicle.

You’ve probably heard the term MacPherson strut; it is actually a shock absorber and coil spring combined into a single unit.

Anti-sway bars

Anti-sway bars or anti-roll bars are used along with shock absorbers or struts to give a moving car additional stability. A metal rod spans the entire axle and effectively joins each side of the suspension together.

When the suspension at one wheel moves up and down, the anti-sway bar transfers movement to the other wheels to create a more level ride and reduce vehicle sway.