Closure operator

Claim 1

IN AN OPERATOR FOR A MULTI-FOLD CURTAIN DAMPER HAVING A FRAME OR SHELL ENVELOPING THE DAMPER CURTAIN AND IN WHICH THE CURTAIN IS CAPABLE OF OPENING AND CLOSING AN AIR PASSAGE DEFINED BY THE FRAME OR SHELL IN RESPONSE TO THE WINDING AND ANWINDING OF ONE OR MORE CABLE SECTIONS ON A MOTOR DRIVEN DRUM, THE IMPROVEMENT COMPRISING A MOTOR HAVING AN OUTPUT DRIVE SHAFT WITH THE MOTOR INCLUDING AN INTEGRAL BRAKE TO PREVENT SHAFT ROTATION WHEN THE MOTOR IS DEENERGIZED; A PLANETARY GEAR SELECTIVELY COUPLING THE MOTOR OUTPUT SHAFT TO THE DRUM TO ROTATE THEREBY THE DRUM RESPONSIVELY TO SHAFT ROTATION, THE PLANETARY GEAR INCLUDING A SUN GEAR FIXEDLY CONNECTED TO THE MOTOR OUTPUT SHAFT AND HAVING A COMMON LONGITUDINAL AXIS OF ROTATION THEREWITH, A PLURALITY OF PLANET GEARS MOUNTED ON A PLANETARY CARRIER AND FIXEDLY COUPLED TO THE DRUM TO ROTATE THEREBY THE DRUM ON THE FOREGOING LONGITUDINAL AXIS OF ROTATION WHEN THE PLANETARY CARRIER ROTATES, AND AN INTERNAL GEAR RING ENGAGING THE PLANET GEARS; AN ELECTROMAGNETICALLY ACTUATABLE CLUTCH SELECTIVELY COUPLED TO THE RING GEAR; AN ELECTROMAGNET WHICH WHEN ENERGIZED ACTUATES THE CLUTCH TO POSITION FIXEDLY THE INTERNAL RING GEAR THEREBY ROTATING THE PLANETARY CARRIER IN RESPONSE TO MOTOR OUTPUT SHAFT ROTATION; A LIMIT SWITCH INCLUDING A SWITCH ACTUATING ELEMENT COUPLED TO THE DRUM AND RESPONSIVE TO A PREDETERMINED NUMBER OF DRUM REVOLUTIONS TO ACTUATE THE SWITCH TO DEENERGIZE THEREBY THE MOTOR UPON FULL OPENING OF THE CURTAIN WITH THE CURTAIN BEING HELD IN THE OPEN POSITION BY THE MOTOR BRAKE; AND SWITCHING MEANS CONNECTED TO THE ELECTROMAGNET TO COMPLETE AND ENERGIZING CIRCUIT FOR THE ELECTROMAGNET TO EFFECT THEREBY CLUTCH ENGAGEMENT TO WIND A CABLE ABOUT THE DRUM UNTIL THE MOTOR ENERGIZING CIRCUIT IS OPENED BY THE LIMIT SWITCH AND THE SWITCHING MEANS WHEN OPENING THE ENERGIZING CIRCUIT DISENGAGES THE CLUTCH TO EFFECT DRUM RELEASE WHICH ENABLES THE CURTAIN TO LOWER THUS CLOSING THE DAMPER.