A shock absorber or shock damper is a mechanical or hydraulic device designed to absorb and decrease the impact of a shock impulses. Shock absorbers convert the kinetic energy of the shock to some other form of energy to dissipate it. A shock absorber is a type of dashpot.
Most used in vehicles, shock absorbers reduce the effect jerks, resulting in improved ride quality and vehicle handling.
There are two major types of shock absorbers: Twin tube and Mono tube.
Twin tube: Also called a "two-tube" shock absorber, this device has two nested cylindrical tubes, the inner, "working tube" and an outer "reserve tube". Twin tube shock absorbers can be basic, gas charged, position sensitive, acceleration sensitive or coilovers.
Mono tube: the mono-tube shock absorber is a gas-pressurized shock absorber that also comes in a coilover format. It is made up of only one tube, the pressure tube, however, it has two pistons.