Electromagnetically controlled permanent magnet brake

摘要

An electrically controllable brake device comprises braking means responsive to both a permanent magnet (12) and an electromagnet (14) which can be energised so as to produce a braking force. The permanent magnet (12) is formed of a rare each material which is strongly resistant to de-magnetisation by the opposed magnetic flux caused by the electromagnet (14), and can thus be placed adjacent the electromagnet (14). <MATH>