An electromagnetic clutch assembly for an automotive air conditioning compressor is designed so that the return force, as a function of axial displacement, is better matched to the performance requirements of the system. A steel armature, which is pulled toward and into driving contact with a pulley...http://www.google.fr/patents/US5377799?utm_source=gb-gplus-shareBrevet US5377799 - Electromagnetic clutch with improved actuation
