| 摘要 |
PURPOSE:To enable the looseness in the direction of rotation to be eliminated, and at the same time, enable a brake mechanism to be shaped into a thin form by placing a torsional spring in such a manner that it comes in pressing contact with the internal surface of a stopper case, and then forming a brake mechanism, which applies the diametral expanding and diametral contracting action of said spring, into an internal external double wall construction. CONSTITUTION:A large diameter torsional spring 11 and a small diameter torsional spring 12 are placed in such a manner that they come in pressing contact with the large diameter wall 10a and the small diameter wall 10b of a stopper case 10 respectively. The hook parts 11b, 12b at one end of each of said springs 11, 12 are engagingly attached to the large diameter claw part 15b and the small diameter claw part 15c of a stopper plate 15, which is formed into one with pinion, respectively. Therefore, on the pinion side, the looseness in the direction of rotation either in clockwise or in counterclockwise cannot be produced. In addition, since the small diameter torsional spring 12 is placed on the inside of the large diameter torsional spring 11, the brake mechanism can be shaped into a thin form.
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