An extension spring is made of spring wire and exerts a load or force when it is stretched. Extension springs offer resistance to a pulling force and are constructed to oppose the axial pulling force. An extension spring (often referred to as a tension spring) is defined by diameter, wire diameter, the extended length, type and the position of the eye loops (English, German or custom).
If an existing spring should be stronger, weaker, longer or just smaller, it can be adjusted in accordance with the design. In addition, the spring should be checked to establish whether it is suitable for the desired applications and if the desired life expectancy is actually achievable.