In current version, motor has FE consumption->stress scale with speed,
I suggest make it has constant FE->stress ratio with speed control,
when you want more stress output from same motor,you connect more coil block at the back of so it increase its FE consumption.

and I suggest use iron for such coil,so you have more reason make iron wire.

if you want,you can it attach coil at the rotation bar side and do more coding with it, and maybe call it iron spring thingy can work too.