Tension springs, also known as extension springs, are coil springs, normally tightly-wound, that are loaded in tension. Tension springs usually have hooks or loops which are attached to components. If these components are moved or pulled apart, the spring opposes this extension, exerting a force to bring them together.
Tension springs have a wide range of uses and are found in many applications, such as switches, levers, braking systems, trampolines, tools, garage doors. They are used in a wide range of industries from rail and agriculture to oil, gas and aerospace engineering.