The Magnetic Particle Clutch : Jacob Rabinow

A clutch is a device for transmitting torque between a pair of rotating coaxial shafts. In 1947, Rabinow invented the magnetic particle clutch (or brake). A chamber between plates on the driven shaft is filled with a mixture of light lubricating oil and carbonyl iron in powder form. An electromagnet (coil) inside the chamber circumference is wired to slip rings mounted atop the chamber. A disc on the end of the drive shaft spins freely in the chamber.

When electrical current is supplied to the slip rings, the coil is energized, magnetic flux is established between the plates of the chamber, and the iron particles are attracted to each other. This produces an almost solid mass, and the plates are locked together. Any degree of slippage or complete locking between driving and driven shafts may be obtained by control of flux.

Objects:
First Laboratory Model of Clutch, ca. 1942
Cutaway Model of Clutch from Subaru, ca. 1942
Photograph of Clutch in Model, ca. 1942
Photograph of Rabinow Demonstrating Clutch with Model, ca. 1942