The steering system on an automobile starts with exerting force on the steering wheel. This turning force is passed on to the pinion gear and is transferred to the rack. The tie rod on the end of the rack pushes or pulls the spindle to make the wheels turn.

The power assist piston is a hydraulic unit that helps transmit force from the rack to the tie rod making it possible to steer the car while exerting less force on the steering wheel.

The pinion gear is attached to the steering wheel by the steering shaft. When the steering wheel is turned, the pinion gear turns. The teeth in the pinion gear mesh with the teeth on the rack, transferring the rotating motion to a side-to-side motion.

The rack is moved side to side by the motion of the pinion gear. The rack pushes or pulls on the tie rods which transmit the motion to the wheels. In a manual steering vehicle, all of the motion is controlled by the pinion gear moving the rack. In a power steering vehicle, there is a piston attached to the rack to help transmit the movement to the tie rods.

The tie rod connects the key parts of the steering mechanism. They pass on the movement from the rack and pinion unit to the spindle connected to the wheel.

The spindle is attached to the wheel and causes the wheel to turn when it is pushed or pulled by the tie rod, thereby turning the vehicle.

The rack and pinion unit houses the rack and pinion gear assemblies as well as the power assist piston.

The tire provides traction for steering and stopping the vehicle.

The purpose of the suspension system is to provide a smooth ride in the car and to help maintain control of the vehicle over rough terrain or in case of sudden stops. There are two basic types of suspension used in most cars today. Strut suspension and Conventional suspension. Suspension systems control the movement of the car and keep the tires in contact with the road, providing a better and safer ride.

Shock absorber's are attached to the car's frame near each wheel on most cars with conventional suspension systems. Shock absorbers are either housed inside coil springs, or mounted beside them.

When your car hits a bump, the spring contracts. The shock absorber works with a piston and thick fluid inside it to keep the spring from rebounding too quickly, making your car ride smoother, improving control and reducing tire wear.

Coil Springs are a component in both Strut and Conventional Suspension systems. When your car goes over a bump or has to stop quickly, the coil spring contracts then rebounds. It is the job of the Strut or Shock Absorber to keep the coil spring from rebounding too quickly.

Most front wheel drive cars have some kind of Strut Suspension. The strut is a special type of shock absorber that helps to minimize the motion of the suspension. The coil spring surrounds the strut assembly. Struts and shock absorbers work in very similar ways. However, struts function as a structural part of the Suspension System, and therefore also affect things like wheel alignment, vehicle control and suspension wear.

Most front wheel drive cars have some sort of Strut Suspension System. In the Strut Suspension System, a coil spring with a bearing plate at each end supports the car. The spring assembly rests on a seat. The Strut Suspension System helps to cushion the movement of the coil spring when a car hits a bump or a pothole and works to hold the tires to the road and provide better vehicle control.