The purpose of a car's suspension is to cushion the effect of a bumpy road on the body of the car. The wheels will jolt with every bump and pothole in the road, and if there were no suspension system the driver and passengers would be bouncing off their seats.
The main components of the suspension are shock absorbers and springs. A shock absorber is a piston filled with oil that is mounted between the wheel axle and the car body. With many cars the shock absorber sits inside the spring so that each time the car hits a bump in the road, the spring compresses, absorbing some of the shock. This also causes the piston to move up inside the shock absorber, the resistance of the oil acting as a damper. This arrangement is normally found on both front wheels of most modern cars.
The rear axle can be dampened by the same method, or alternatively a leaf spring could be used. This consists of an arrangement of steel strips on top of each other, (typically three or four strips) with a slight curve. One end is fixed to the body of the car whilst the rear axle is fixed about half way along the strips. If the wheel takes a jolt it will then be dampened by the steel strips. Also between the axle and the body is a shock absorber, giving a similar dampening effect to the front wheels. As new models are introduced the suspension systems are improved, with many cars now having torsion bars and anti-roll bars.
