PROBLEM TO BE SOLVED: To provide an unexcited operation type electromagnetic brake of permanent magnet type allowing to release braking by hand control without excitation to an exciting coil. ;SOLUTION: This brake is composed of a securing part 10 provided with a yoke 11 and an exciting coil 12 and a rotating part 20 being rotatable to the securing part. The rotating part 20 is provided with a hub 22 secured to a rotating shaft to be braked 21, an armature 24 mounted to an outer periphery of the hub 22 through a return spring 23, and a permanent magnet 25 mounted to the armature 24. The armature 24 comprises an outer flange 24a on a side contacting to the yoke 11 and has a short-circuit plate 26 contacting to the permanent magnet 25 mounted. A magnetic ring 28 mounted to an outer periphery of the permanent magnet 25 is movable in an axial direction and switchable between a non-demagnetizing position where the magnetic ring 28 contacts to the outer flange 24a and a magnetizing position where the magnetic ring 28 is apart from the outer flange 24a and covers the short-circuit plate 26 to leak magnetic flux of the permanent magnet 25.;COPYRIGHT: (C)2001,JPO
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