A suspension system comes in two different designs—independent and solid (live) axle. Most cars use an independent suspension system, where each wheel moves up or down independently without affecting the other wheels. Some cars and most trucks use a solid axle suspension in the rear, where the axle moves up and down like a seesaw and the movement of one wheel causes a corresponding movement in the other wheel.
Vehicles with independent suspension systems offer a more comfortable ride and have better handling characteristics. Solid axle systems are stronger, less expensive to build, and have more load bearing capacity, but offer a rougher ride.
The two most common types of steering systems are rack & pinion (used on most cars) and recirculating ball (used on trucks and utility vehicles). The rack & pinion system is similar to the independent suspension system in that it offers better control and handling. The recirculating ball system, like the solid axle system, is stronger and more robust, which is better suited for larger vehicles and trucks.
Shock absorbers dampen the shock the suspension receives when the vehicle is driven over rough or uneven road surfaces. A suspension strut—also referred to as a MacPherson strut—combines a shock absorber and coil spring into one assembly. This reduces the weight of the components and saves space, providing a lighter and more compact suspension system.
Rack & Pinion Steering Gear
Most cars use a rack & pinion steering system in which the steering wheel turns a steering shaft that is connected to a pinion gear. This gear moves a steering rack left and right. The rack has two arms attached to it called tie rods, which connect to the steering arm and help steer the wheels.