A torsion spring is a type of spring that generates a restoring torque when subjected to a twisting force (torque).Unlike extension springs or compression springs, torsion springs store and release energy through twisting. The surface of a torsion spring can be treated with yellow chromate zinc plating, also known as yellow zinc plating, which is one type of zinc coating. A torsion spring, also called a torsional spring, is designed to withstand axial loads where the applied load is a torque or rotational force. The ends of the spring rotate by an angle when a load is applied.