The shock absorber is a dampener which absorbs the vibrations caused in the vehicle by converting the car's kinetic energy into heat energy. They are also responsible for keeping the tires in contact with the road while providing an optimal ride quality and safety. While cornering or negotiating sharp turns, the shock absorber works to prevent an excessive vehicle body lean or roll in any direction. In addition to stabilizing the vehicle, the shock absorbers also contribute to minimizing the tire wear and protect the overall suspension system, as well.
The shock absorber or shock is located between the car's frame and wheels. The shock absorber mount is attached to the piston rod which is connected to a piston. The piston is fitted inside a cylinder filled with hydraulic fluid. This simple mechanism dampens most vibration in the vehicle. When the shock receives an impact due to a bump, it compresses the fluid, exerting pressure inside it. A piston attached to the top of the cylinder moves up and down, based on the suspension movement. As the piston moves, the fluid is forced out through orifices, which along with the check-valves, limit the amount of fluid that flows through the piston. This slows down the piston movement and thereby, reduces the spring movement, as well. This ensures that the driving experience is bump-free.
There are two common kinds of shocks used in vehicles: twin-tube and mono-tube shock absorbers, out of which the twin-tube shock absorbers are the most common types used in vehicles. The twin-tube shock uses compression and expansion to accomplish its function. During the compression phase, the shock receives vibrations and pushes the piston that is in contact with the hydraulic fluid downwards, resulting in the compression of the hydraulic fluid. This compression results in the conversion of the kinetic energy into heat energy. In a hydraulic system, for every compression that takes place, it is often followed by an equivalent expansion process. The same is true of the shock, as well. During the expansion phase of the twin-tube shock, the piston moves upwards and the fluid gets transferred to a chamber above the piston. On the other hand, the mono-tube shock comprises a single pressure tube and two pistons called the working and dividing pistons. The pressure tube consists of both the hydraulic fluid and air which are separated by the pistons.
Some shock absorbers allow drivers to manually adjust the valves in the shock absorber for better control of the ride, it can also be achieved remotely in some high-end vehicles. Often, it is the coilover shocks that are confused with struts due to their similar designs.