Tension & Extension Spring
Tension springs are another name for extension springs. Extension springs have no pitch in between the coils and have a function opposite to that of compression springs. While compression springs are meant to be compressed extension or tension springs are meant to be extended or pulled.
The load applied to extension springs stretches its tightly wound coils apart and spreads them open. Tension springs resist the pulling force that is placed upon them and this creates a sling back effect when the force is removed, causing it to return to its original shape. This function makes them ideal for lifting heavy objects and assisting in the lifting or dispersing of certain loads.