A drive hub is mounted to an element and has a surface which presents away from the element and produces a magnetic field which extends from and returns to the drive hub. If depicted graphically, concentrations of field lines would appear to extend from two or more North domains defined in the surface to two or more South domains defined in the surface, the North and South domains being arranged to encircle a rotation axis in spaced alternating relation. A driven hub is spaced and frontwardly adjacent to drive hub, coupled to the element and constrained against movement but for axial rotation. Driven hub includes non-magnetic, electrically-conductive material having low magnetic permeability and receptors, receptors having a high magnetically permeability, being spaced to the axis and arranged such that rotation of the drive hub relative to the driven hub creates a net rotational force that urges co-rotation of the hubs.
