Hydrospring

A hydrospring is a mechanical device that performs a similar function to a spring. The advantage of a hydrospring over a normal spring is the increased damping that it performs. The damping is achieved by hydraulic fluid (typically oil) being driven through holes in a piston, as that piston moves in response to a force.
Hydrosprings are used in a variety of applications: shock absorbers, vibration dampers on train suspension, bulldozer blade shock absorbers and as recoil absorbers for artillery.