Tension springs are often produced with an initial tension, which is a type of internal force to keep the rings in this type of spring, the rings forming the spring are stuck together and usually the beginning and end of the springs have hooks, when they are subjected to tension, the increase They last and return to their original state after the load is removed. In this type of springs, the outer diameter of the spring has an indirect relationship with the strength of the spring, and as the outer diameter increases, the strength of the spring decreases. For an example of this model, we can refer to the door spring that closes the door.
