Torsion Springs General Data: Torsion springs, whose ends are rotated in angular deflection, offer resistance to externally applied torque. The wire is subjected to stresses in bending instead of stresses in torsion as in extension or compression springs. Most torsion springs are close wound and decrease in diameter as they are deflected. Other types of torsion springs include double torsion springs and springs having pitch between the coils to minimize friction. Special considerations should be given when choosing a leg configuration for your torsion spring. Keep in mind, the suggested allowable hook stress in torsion is 30-45% (depending on material) of its MTS (Minimal Tensile Strength), while that for bending is 75% of its MTS. The Spring Team engineering department will gladly help you with your leg end configuration. The functional design characteristics of the spring should be given as mandatory specifications. Secondary characteristics, which may well be useful for reference, should be identified as advisory data. This practice controls the essential requirements, while providing as much design flexibility as possible to the spring manufacturer meeting these requirements. Spring Team always verifies incoming designs to insure manufacturability and informs customers when designs are over stressed or not capable of being produced. Designs are always verified using SMI's (Spring Manufacturers Institute) most current released computer design program and our engineering department will gladly share the derived printouts with those interested. Spring Team has a design handbook which we will gladly ship out to engineers to assist their spring development needs.