Explained in the easiest way possible, an electromechanical brake uses electromagnetic force for retarding or stopping any object performing a kinetic or mechanical motion. Some people confuse electromagnetic brakes with eddy current brakes, since both of them rely on electromagnetic force. The difference is that electromagnetic brakes depend largely on friction, and eddy current brakes use magnetic force directly. Also, many people seem to think that electromagnetic and electromechanical brake are different things, but actually they aren’t, just that the term ‘electromechanical’ is not in use anymore.
Design and how they work
The most basic electromagnetic brakes design comes down to a a few elements: a coil in a shell, a hub and an armature. The coil shell is almost always made of carbon steel because this material is great at combining strength with magnetic-properties. The coil is made mainly of copper, although aluminium is used in rare cases. The coil is held in the shell by a bobbin or epoxy adhesive.
The electromagnetic brakes design of this kind makes the entire work process quite easy: when the electric circuit is activated, the coil gets energized. The current that runs through the coil starts generating a magnetic field which starts producing magnetic flux. The magnetic flux is what does all the work; when that flux overcomes the air gap between the armature and the field the magnetic attraction pulls the armature back, which results in connecting it to the hub and finally – contact with the rotor.
That’s how the stopping process in general works. Now the difference is that in brakes, there’s no rotor, so the magnetic flux acts directly between the field and the armature. Here, the field connects to a magnetic frame or a torque arm that handles brake torque. So when the armature makes contact with the field, the torque instantly transfers into the field housing or the machine frame resulting in decelerating the load. This changes the speed.
If you’re looking into electromagnetic brakes than you’re probably working in industries like mechanical maintenance of locomotives in trains and trams, industrial and robotic applications and similar. Electromagnetic brakes in locomotives for example, are the link between the torque and the electromagnetic braking component. In trains and trams, they present the element that’s pressed by magnetic force to the rail. The latest innovations have led to the development of electromagnetic brakes for airplanes, which comes down to a combination of a motor and a generator being used as a motor first to speed prior to touchdown and then as a generator to provide the regenerative breaking.