spring

Device, usually a metal coil, that returns to its original shape after being stretched or compressed. Springs are used in some machines (such as clocks) to store energy, which can be released at a controlled rate. In other machines (such as engines) they are used to close valves.

In vehicle-suspension systems, springs are used to cushion passengers from road shocks. These springs are used in conjunction with shock absorbers to limit their amount of travel. In bedding and upholstered furniture springs add comfort.