The coupling includes drive and driven hubs. The drive hub is mounted to arotating element and has asurface presenting away therefrom. In the absence of externalities, a magneticfield is producedwherein, if depicted graphically, concentrations of field lines extend fromtwo or more North poledomains defined in the surface to two or more South pole domains defined inthe surface, the domainsbeing spaced apart and encircling the rotation axis in alternating relation.The driven hub is disposed inspaced, frontwardly adjacent relation to the drive hub, is fixed to therotatable element and is at leastsubstantially constrained against movement but for rotation with the rotatableelement. The driven hubincludes: a rotor body of a non-magnetic, electrically-conductive materialhaving relatively low magneticpermeability； and a flux ring of material having a relatively highmagnetically permeability arranged inspaced relation to the body.
