These springs are typically made from round wire and are closed coil wound, however, various cross section material maybe utilized. These springs are used to counteract a pulling force of a mechanism. These types of springs usually have loop ends, but extension springs can have various hook configurations based on the design requirement. Most helical extension springs are coiled with initial tension, this is the force required to separate the adjacent coils. Common applications of extension springs include farm equipment, automotive mechanisms, trampolines and many other applications.
Design parameters for the body of the extension spring are similar to those of compression springs.