Parts of the suspension system

The suspension is positioned between the body and the tires of a car, and works to support the car body while also absorbing shocks received by the tires.

Fig.8-1 Suspension mechanism (for a MacPherson strut type)

●Springs

The spring is the first component that absorbs the shock applied to the body of a car while driving, and alleviates that shock while also supporting the car at a certain height. This is an important component that greatly affects the control stability of a car. In passenger cars, metal coil springs are the most common, but there are “air suspensions” where air pressure is used instead.

Springs

●Dampers

When a coil-shaped spring receives a load, it dampens the shock by contracting, but by itself it will not stop oscillating back and forth. What prevents this movement are the dampers (also called shock absorbers). Typically, a shock absorber involves a mechanism whereby the resistance of a piston moving up and down inside a cylinder sealed with oil and gas is used to stop unwanted movement. As with the springs, this component greatly affects control and road-contact characteristics.

Dampers

●Suspension Arms

These are parts that control the movement of the wheels; they are connected via bushings to the body and axles. There are many different shapes (like A arms and I arms) but in the case of a double wishbone type, where there is one arm on the top and bottom, the one on top is the upper arm and the one on the bottom is the lower arm.

●Suspension Bushings

These are shock- and vibration-absorbing materials fitted to the joints of metal links and arms, and to attachment points on the car body. Normally they are made of rubber, but if the bushing is too soft it will deform under heavy load and cause the suspension to move in an unwanted way. As a result, in some cases, metallic ball joints called pillow-ball joints are used.

●Stabilizer (also Sway Bar, Anti-roll Bar)

This is a stabilization device which uses the twisting of a torsion bar spring to restrict the rolling motion of a car body. The ends of the bar are attached to both lower arms of the suspension, and the stabilizer acts only when the left and right tires are moving in a different way. For example, while cornering, the suspension on the outside of the corner will tend to sink down while the inside will lift up. The stabilizer will restrict the movements of the left and right wheels from their suspension arms in order to stabilize this rolling motion of the car.

Stabilizers