1. A friction device sometimes called a shock absorber . Used for controlling and damping spring oscillations . The springs actually absorb road shocks; the dampers convert the energy imparted to the springs into thermal energy (by friction), which is dissipated to the atmosphere or the vehicle's chassis . Dampers are distinguishable by the type of friction involved, mechanical or hydraulic , but most modern cars used tubular-shaped hydraulic shock absorbers. Because they affect up and down wheel motions, dampers are an important link in tuning a vehicle's ride and handling. Also see pulsation damper , vibration damper , and harmonic balancer .
2. A moveable plate which permits or restricts the flow of liquids or gasses.