Shock absorber

Dictionaries give two broad definitions of the term shock absorber; as 'a device for absorbing the energy of sudden impulses or shocks in machinery or structures' or as 'a device on a vehicle, especially a car or an aircraft, which reduces the effects of travelling over rough ground or helps it to land more smoothly.'

A shock absorber is a mechanical support designed to smooth out a sudden shock impulse and dissipate kinetic energy over an extended period of time. There are several commonly-used approaches to shock absorption:

• Hysteresis of structural material, for example the compression of rubber disks, stretching of rubber bands, or bending of steel springs
• Dry friction, for example in wheel brakes
• Fluid friction, for example the flow of fluid through a narrow orifice (hydraulics)
• Compression of a gas, for example pneumatic shock absorbers.
• Magnetic effects
• Inertial resistance to acceleration

Pneumatic and hydraulic shock absorbers commonly take the form of a cylinder with a sliding piston inside. Spring-based shock absorbers commonly use helical springs or leaf springs, though coil springs can be used to absorb torsional shocks as well.

Shock absorbers are an important part of automobile suspensions, aircraft landing gear, and the supports for many industrial machines. Large shock absorbers have also been used in architecture to reduce the susceptibility of structures to earthquake damage.