| 摘要 |
<p>PURPOSE:To shorten the axial dimension of a device by performing the switch operation between braking and nonbraking without shifting a magnetic support ring. CONSTITUTION:An immovable magnetic support ring 20 is arranged inside a braking drum 13 coupled with a rotary shaft 4, and many cavities 27 are arranged at equal intervals in circumferential direction in the magnetic support ring 20. A columnar permanent magnet 32 is stored in the cavity 27, and the rotary shaft 31 parallel with the rotary shaft 4 of the braking drum 13 coupled with each permanent magnet 32 is supported rotatably by the end wall of the magnetic support ring 20. By rotating the partial gear 18 coupled with the rotary shaft of the permanent magnet 32 a quarter turn by a rotating means, it is switched between the braking position where the polarities opposed to the inside periphery 14 of the braking drum 13 of many permanent magnets 32 are different alternately and the nonbraking position where the polarities of the permanent magnets 32 are drawn up in circumferential direction and besides are opposed with the polarities different.</p> |
