The load must be applied in such a way that the torque application binds the spring (see figure), as it is strongest in this direction. To minimise the friction against the shaft, use of fixed tension ends is preferable.

Torsion springs have a linear spring characteristic, i . e . if a spring is turned 10° to provide torque of 1 Nmm, the same spring will provide a torque of 2 Nmm at 20° torsion.

Torque
Torque is equal to force x leg length: M= F x A. The closer to the end of the leg the load is applied, the less counter force is created. The following tables specify torque in Nmm, i . e . the force obtained on the leg 1 mm from the centre.

Permitted load, life
If the maximum torque angle (φ) as specified in the following tables is used, a maximum of 10 000 load cycles is permitted. If only 80% of the permitted torque angle is used, the lifespan of the spring increases to 200 000– 400 000 load oscillations. If only 70% of the permitted torque angle is being used, an almost infinite lifespan can be expected.

Ends
The ends in this standard stock catalogue are produced to a basic design, i.e. straight.