Magnetic Particle brakes, Magnetic Particle Clutches - Principle and function

Principle and function

Magnetic particle brakes and clutches are of simple design. Due to their size they produce a high torque compared to for instance hysteresis brakes. They are having two rotors (inner and outer) and an air gap between these two rotors where the magnetic particles are dispersed in. An electric current passing through the coil creates a magnetic field, which aligns the magnetic powder into the gap. The higher the current, the more rigid the connection between the inner and outer rotor becomes. The principle is the same for brake, clutch and torque limitor.


Noisless work
Torque directly proportional to current
Torque independant from r.p.m. (starting from 30 min)
Strong design, units are able to be used with steady slipping
High torque range to be controlled (approx 1:50)


Torque control, torque limiting
Tension control at winding, unwinding
Starting clutch operation
Calculated braking and starting
of certain masses and inertias

  Switching times

Switching times with magnetic particle brakes are dependable on the kind of electrical supply. There are for instance shorter delays when switching on the DC-side as to switch on the AC-side. Also the switching delay can be shortened by having one or more shunts behind the brake/coupling.

Switch in time and switch off time are shown with their characteristic on graph No. 2 they are available for every unit on request.

mobac GmbH · Kieler Str. 23· D-24247 Mielkendorf · Tel. +49 (0)4347 90477-0 · Fax +49 (0)4347 90477-10 ·