Magnetic drives or couplings transmit mechanical force without any mechanical connection. They are usually made up from two concentric rings, but other arrangements (such as identical flat rings facing each other) are not uncommon.
The most common arrangement carries rare earth magnets with alternating polarity on both parts of the drive. It is used in pumps, autoclaves, mixers etc.
A very rough idea of the possible torques can be obtained from the diagram below:
The diagram is meant as a crude indicator if a magnetic drive is a possible option for a given problem. Depending on the details of your application, the possible torques may be very different. Please contact us for a design taylored to your requirements. You may want to consult our 
magdrive checklist (PDF) first.
The setup is similar to the synchronous drive, but one of the magnet rings is replaced by copper or another electrically conductive material. This results in a smooth breaking force that grows with the speed difference between the two parts. They are frequently applied for their wear-free breaking capabilities without any separation wall.
Here, the rare earth magnets on one side are replaced by a hysteresis material with intermediate properties between rare earth magnets and soft-magnetic materials. The result is a smooth, wear-free friction device that limits the applied torques to a perfectly reproducible level.
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