The electromagnetic Powder Coupling combines the resilience of a fluid coupling with the locked-in stability of a friction clutch. Torque is transmitted by a specially alloyed dry ferromagnetic powder, the apparent viscosity of which may be changed by modulation of the field coil current . The couplings can sustain continuous slip (within their empirically estabilished heat ratings) at a precise and stable torque value, which is determined by excitation level.
