Friction coupling

Claim 1

A FRICTION COUPLING COMPRISING TWO MEMBERS RELATIVELY ROTATABLE ABOUT A COMMON AXIS AND HAVING OPPOSED ANNULAR WALLS CONVERGING RADIALLY TOWARD EACH OTHER AND COACTING TO FORM A GROOVE, A FREE FLOATING ARCUATE BAND OF A CROSS-SECTION COMPLEMENTING THE CROSS-SECTION OF AND LOOSELY SEATED IN SAID GROOVE, SAID BAND HAVING AN EXPOSED PERIPHERAL SURFACE, AN ACTUATOR FOR PRESSING SAID BAND RADIALLY INTO SAID GROOVE COMPRISING A HELICAL COIL OF RESILIENT WIRE TELESCOPED WITH SAID SURFACE, MEANS ANCHORING ONE END OF SAID COIL TO ONE OF SAID MEMBERS, AND MEANS ON THE OTHER MEMBER CONTROLLING THE WINDING AND UNWINDING OF SAID COIL TO CHANGE THE COIL DIAMETER IN OPPOSITE DIRECTIONS WHEREBY TO APPLY RADIAL PRESSURE TO SAID BAND AND FORCE THE SAME INTO SAID GROOVE AGAINST BOTH OF SAID WALLS TO ENGAGE THE COUPLING OR RELEASE SUCH PRESSURE AND DISENGAGE THE COUPLING, ONE OF SAID GROOVE WALLS BEING DISPOSED RELATIVE TO SAID AXIS AT A SUBSTANTIALLY GREATER ANGLE THAN THE OTHER GROOVE WALL WHEREBY TO DEVELOP FRICTION TORQUES OF DIFFERENT MAGNITUDES BETWEEN THE OPPOSITE SIDES OF SAID BAND AND THE RESPECTIVE WALLS ON SAID MEMBERS, AND THE RESULTANT OF SAID FRICTION TORQUES ACTS IN THE SAME DIRECTION AS SAID WINDING MEANS WHEREBY SAID BAND, ACTING UNDER SUCH TORQUE DIFFERENTIAL, COOPERATES WITH SAID COIL TO FORM AN AUXILIARY FRICTION CLUTCH AUGMENTING THE ACTION OF SAID WINDING MEANS IN CHANGING THE DIAMETER OF SAID COIL.