We were all taught that the machine CONVERTS electrical energy into mechanical energy, and that this mechanical energy production can only happen in a circuit location where the current is moving through a "voltage drop".
This is apparently not true!!
The tell-tale behavior is most easily seen when the machine is operated as a generator. When a current flow is established through an external load, it still energizes the reverse torque production inside the generator in the windings where the voltage is rising!
from: Electric Motor Secrets Part 2 - The Lockridge Device, a lecture given by Peter Lindemann in November 2010 at the Renaissance Charge Conference.