Constant Torque Spring Design

Specify shaft viewing direction, positive rotation and sensor sign on the test diagram. Report resisting and driving torque consistently.

Include repeated stops, reversals and dwell at actual index positions instead of testing only continuous rotation.

Define the residual load and foreseeable external loads independently of nominal spring balance. A latch should be rated through the mechanism’s load path.

Backlash, friction and the transfer path may affect initial response even when steady output is nearly constant.

Check rotating assembly geometry and contact first, then compare with the spring’s own measured output.

Define the permitted transfer window and required retained strip on both drums. The total material available is not automatically useful rotation.