Electromagnetic spring biased clutch having a negative spring characteristic

Claim 1

IN A MAGNETIC CLUTCH OF THE KING REFERRED TO, TWO SHAFTS IN CO-AXIAL ALIGNMENT, AN EXCITER COIL CONCENTRIC WITH SAID SHAFT, A BODY OF MAGNETIC MATERIAL PARTIALLY SURROUNDING SAID COIL AND ADAPTED TO PROVIDE FOR THE MAGNETIC FIELD GENERATED BY SAID COIL A CONTINUOUS FLUX PATH INTERRUPTED AT ONE PLACE BY A SUBSTANTIALLY WIDE GAP IN SAID BODY OF MAGNETIC MATERIAL, A FIRST ROTATABLE RING-SHAPED ARMATURE ADJACENT SAID WIDE GAP, A SECOND ROTATABLE RINGSHAPED ARMATURE CLOSELY ADJACENT SAID FIRST ARMATURE SO AS TO PROVIDE BY THE CO-ACTION OF BOTH OF SAID ARMATURE SO A MAGNETIC BRIDGE OF LOWER RELUCTANCE FOR SAID FLUX ACROSS SAID WIDE GAP, SAID FIRST ARMATURE BEING RIGIDLY FASTENED UPON ONE OF SAID SHAFTS, THE SECOND OF SAID ARMATURES BEING FASTENED TO SAID SECOND SHAFT BY A THIN A WEB HOLDING SAID RING-SHAPED ARMATURE IN PERMANENT CONCENTRICITY RELATIVELY TO SAID SHAFT WHILE SAID WEB IS READILY YIELDABLE TO LIMITED AXIAL DISPLACEMENTS OF SAID SECOND ARMATURE WITHOUT GENERATING OPPOSING AXIAL FORCES OF SIGNIFICANT VALUE, AND A SYSTEM OF RESILIENT MEAN ADJUSTABLE INDEPENDENTLY OF SAID WEB FOR IMPOSING PREDETERMINED RESILIENT AXIAL FORCES UPON SAID SECOND ARMATURE, SAID RESILIENT MEANS COMPRISING AT LEAST ONE BEVEL TYPE ANNULAR SPRING ELEMENT AND MEANS FOR CAUSING A PREDETERMINED PRE-STRESS IN SAID ELEMENT FOR OBTAINING A NEGATIVE SPRING CHARACTERISTIC IN THE OPERATING RANGE OF SAID SYSTEM OF RESILIENT MEANS.