Quote Originally Posted by JohnHaine View Post
That's true when tightening but loosening is a different matter as the spindle will be stationary.
It is the same for tightening and loosening. The operating principle doesn't change. The average torque required to spin the module is low, but the impact torque resulting from the hammer hitting the anvil is high. The impact happens two times every full revolution. The impact torque depends mostly on the spindle RPM.

The main difference between tightening and loosening is that for loosening, the spindle needs to overcome the initial module resistance from the standstill. The resistance comes from the need to overcome the hammer return sprint in order to depres the hammer. Once the hammer is depressed, the anvil (top of the module) can slide over it and make the rotation.