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The clutch model under study was mounted in a lathe, and a strain gage was connected to the output shaft to measure the output torque.

Jacob Rabinow invented the Magnetic Particle Clutch in 1947 during his work on ordnance at the National Bureau of Standards. The particle clutch used a mixture of light lubricating oil and powdered carbonyl iron inside a chamber connecting two free spinning plates. When an electromagnet attached to the chamber was energized, the iron particles would magnetize and attract each other, producing an almost solid mass, which locked the plates together. Controlling the magnetic flux would control the amount of torque between the plates. Because Rabinow invented the Magnetic Particle Clutch as part of his work at the National Bureau of Standards, the United States Government owned the U.S. patent. However, in partnership with his brother Joseph, Rabinow did file for patents in 22 foreign countries. Due of the simple design, precise torque control, smooth operation, and long life, the device found wide application. It was used in Renault and Subaru automobiles in Europe and Japan, in airplane controls, and in the disc file of the IBM RAMAC computer.