Katy Spring manufactures single, double and spiral springs, which are torsion springs with a helical shape. These helical springs exert a torque or rotary force and are subject to bending stresses.
Double torsion springs (double body torsion springs) are comprised of a right-hand and a left-hand coil section which are two sets of coils: one wound clockwise, the other counterclockwise. It combines these two separate torsion springs into one unit by bridging them at the middle. Both sides work in parallel to double the torque output. Double torsion springs are designed using single bodied torsion spring methods, but the rate for a double torsion spring is equal to the sum of the rates for each component. In other words, double torsion springs have rates four times those of single-bodied types for wire diameter, coil diameter and wire length.