Abstract: The electro-mechanical converter, that can be considered a unipolar motor, includes a rotatable rotor made of conductive but low permeability material having two axially spaced, radially protruding integral disks. The first disk is larger than the second disk, and two toroid magnets are disposed on either axial side of the first disk. The two magnets have opposing poles facing each other. The two magnets establish a circumferential, unidirectional magnetic field through the first disk over a radial mid-section of the disk. D.C. current is introduced at the edge of the disk, at a fixed location relative to the rotatable rotor via a mercury bath. The D.C. current is removed from the rotor assembly via the second disk and a second mercury bath.