| 摘要 |
A case, a coil spring, a sliding disc and a rotational disc are contained, and the following construction is equipped. The case has a positioning recess portion on the inner wall thereof. On the peripheral surface of the sliding disc is provided a projecting portion which is engaged with the positioning recess portion of the case to suppress the rotation thereof with respect to the case. One end face of the sliding disc and one end face of the rotational disc are confronted to each other, and cam portions which are engaged with or separated from each other in connection with the rotation of the rotational disc are formed on both the confronting end faces. The cam portion formed on the sliding disc projects to the outside of the outer peripheral surface of the sliding disc.
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