What is an electromagnetic particle (powder) brake or clutch and what are its advantages and disadvantages?
Electromagnetic particle brakes and clutches operate on the same principles as other electromechanical brakes and clutches, but they are unique in their design because of the wide operating torque range available. In general, these devices are constructed with a gap between two armatures or poles and a shaft-mounted rotary member extending into the gap in spaced relation to the two armatures. The gap between the opposite sides of the rotary member and the adjacent armatures is filled with magnetic particles which function as the clutching medium. Magnetic particles are located in the powder cavity. Without applying any current, they sit in the cavity, however, when current is applied to the coil, the magnetic flux that is created, tries to bind the particles together. As the current is increased, the binding of the particles becomes stronger. Under application of a magnetic field between the armatures, the normally fluid particles become a kind of dense mass, thereby applying frictiona
