How magnetic particle brakes work?
Powder brakes are comprised of an electromagnet and a disk inside a powder chamber. The Powder_Brake_200disk can spin using a shaft that extends to the outside of the chamber. Without any magnetic field the powder acts like a fluid and the disk can spin freely. A magnetic field produced by the electromagnet will harden the powder causing friction so that the disk can no longer spin freely. The tension is controlled by the strength of the electromagnet.