| 摘要 |
PROBLEM TO BE SOLVED: To suppress rotation of a rod and to obtain its smooth reciprocating motion by making the sidewall surface of the rod end part of an actuator in contact with the projecting wall surface of the end part of a magnet supporting cylinder. SOLUTION: A guide cylinder 10, made of a non-magnetic material and provided with many ferromagnetic plates 15 at equal intervals in the circumferential direction is arranged inside a brake drum 7, to support a magnet supporting cylinder 14 that comprises magnets 24 connected inside the guide cylinder 10, in such a way that the polarity of each magnet which faces each ferromagnetic plate 15 is made different alternately in the circumferential direction. An actuator 20, that rotates the magnet supporting cylinder 14 forward and reverse to a braking position and brake-releasing position, is fixed to the end wall of the guide cylinder 10 to face the circumferential direction. The sidewall surface of the end part of a rod 37 of the actuator 20 is made in contact with the projecting wall surface provided on the end wall of the magnet support cylinder 14. The groove of a semi-oval shape provided on the side wall surface is fitted to the shaft part 46 supported to a projecting wall 41. A protruding piece that extends in the radial direction is provided on the projecting wall 41 to expand the projecting wall surface and the projecting wall surface is made cylindrical.
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