EXTENSION SPRINGS are found in garage door assemblies, vise-grip pliers, and carburetors as well as thousands of other places. When they are attached at both endsand when the components they are attached to moves apart, the spring tries to bring them together again.

Extension Springs are wound with initial tension known asstored energy which holds the coils together and offers resistance to a pulling force. Springs can have many different styles of ends, the most commontypes of loops and hooks are Machine and Crossover. They can be closed (loops) or open (hooks).
Machine End: Wire comes directly off the body, then forming a circle across the center
Crossover End: Wire comes across the center of the spring
Double Loop: end consisting of two coils with no gap between the coils and the end of the wire

TORSION SPRINGS can be found on door hinges, door locks and clipboards as well as thousands of other places. When the ends of the torsion spring are attached tothe component, and when these components rotate around the center of the spring in the direction that winds the coil, the spring tries to push them back to theiroriginal position. Torsion springs offer resistance to externally applied torque as the ends are rotated in angular deflection. Commonly used over an arbor or mandrelfor support. Torsion springs are subjected to bending stress rather than torsional. Normally close wound and are left hand or right hand wound.Torsion springs are selected based on the Degree of Deflection required: usually 90, 180, 270 or 360° from the spring body.

Length of Leg: the length of the torsion spring leg is measured from the center of the body to the end of the leg or tip
Direction of Wind: torsion springs should be used in the direction that winds the coil