Differential magnetic forces at the North and South poles of the magnets provide the driving force to turn the rotor. The stator contains a ring of spaced magnets backed by a high magnetic-permeability sleeve.    Three or more arced armature magnets are mounted in the armature which has a belt groove for power transmission. The armature is supported on ball bearings on a shaft that either screws or slides into the stator unit.    Speed control and start/stop action is achieved by the simple means of moving the armature toward and away from the stator section

U.S. Patent No. 4,151,431