An extension spring or tension spring is a length of tightly coiled metal, usually steel with hooks or loops at either end. Extension springs absorb and store energy. You can find out more in our extension springs guide.

What does it do?

An extension spring is a component that creates a resistance to a pulling force. Extension springs work by trying to pull two objects back together. The attached spring is pulled in opposite directions and the force and the stored energy to pull the two objects back together.

Types

Extension or tension springs selected by a few key attributes, they are:

• Material – Steel or stainless steel
• Free length - The overall length of the spring in its unloaded position
• Max extended length – The length of the spring when it is fully extended
• Outside diameter – The outside diameter of the springs coils
• Wire diameter – The diameter of the metal used to make the spring
• Spring rate – The force, quoted in N/mm
• Max load – The load when the spring is at full extension

Uses

• Garage doors
• Automotive
• Trampolines
• Lever mechanisms