Band type friction coupling

Claim 1

A FRICTION COUPLING HAVING, IN COMBINATION, TWO MEMBERS DISPOSED END TO END AND MOUNTED FOR RELATIVE TURNING ABOUT A COMMON AXIS, ANNULAR FRICTION SURFACES ON THE RESPECTIVE MEMBERS, ONE OF SAID MEMBERS BEING A DRIVER, A FREE FLOATING FRICTION BAND EXTENDING AROUND SAID SURFACES FOR FREE TURNING RELATIVE THERETO, SAID BAND BEING CHANGEABLE IN DIAMETER TO GRIP SAID SURFACES FRICTIONALLY AND THEREBY TRANSMIT TORQUE FROM THE DRIVING MEMBER TO THE OTHER MEMBER, A MULTIPLE TURN HELICAL COIL OF MAGNETIC MATERIAL LOOSELY TELESCOPED WITH SAID BAND, MEANS ANCHORING ONE END OF SAID COIL TO ONE OF SAID MEMBERS, THE TURN AT THE OTHER END OF THE COIL BEING FREE AND CONSTITUTING A MAGNETIC ARMATURE, A MAGNETIC CORE CARRIED BY THE OTHER OF SAID MEMBERS AND HAVING AXIALLY FACING POLE FACES DISPOSED CLOSELY ADJACENT ONE SIDE OF SAID BAND AND OPPOSING SAID ARMATURE TO FORM THEREWITH A FLUX PATH EXTENDING AXIALLY INTO AND OUT OF THE ARMATURE, MEANS FOR CREATING MAGNETIC FLUX THREADING SAID PATH TO DRAW SAID ARMATURE AND POLE FACES INTO GRIPPING ENGAGEMENT AND THEREBY DERIVE A PILOT TORQUE FOR VARYING THE DIAMETER OF SAID COIL IN A DIRECTION TO PRESS SAID BAND AGAINST SAID SURFACES, ONE SIDE OF SAID BAND EXTENDING AXIALLY INTO THE PLANE OF SAID END TURN AND TELESCOPING WITH THE LATTER SO AS TO BE ENGAGED BY SUCH TURN AND HOLD THE SAME SEPARATED AT ALL TIMES FROM THE MEMBER BENEATH THE BAND.