| 摘要 |
A guide tube 10 formed of a non-magnetic material and having a hollow portion in the shape of a rectangle in section is disposed interiorly of a brake drum 7 connected to a rotational shaft 1. A number of ferromagnetic plates 15 are connected at peripherally equal intervals on an outer tubular portion 10a of the guide tube 10. Magnets 24 and 24A are connected to outer peripheral surfaces of a movable magnet support tube 14 and an immovable magnet support tube 14A repectively so that their polarities opposed to the ferromagnetic plates 15 are peripherally alternately different. The magnet support tubes 14 and 14A are disposed in the hollow portion of the guide tube 10. An area of an outer surface 50a of the ferromagnetic plate 15 is made to be narrower than that of an inner surface 50b thereof, and the outer surface 50a is biased forward in a rotational direction of the brake drum 7 from the inner surface 50b. <IMAGE> |
