| 摘要 |
<p>A clutch 61 has a clutch housing 50 that rotates with a spindle 12 and that has inner teeth 50a; a pair of pawls 41 each pawl having an engaging section 41a that can engage with the inner teeth 50; a gear wheel 57 that is joined to a motor 34 and has a pair of pawl sliding grooves 57c that hold the pawls 41, respectively, such that the pawls 41 can move in the pawl sliding grooves 57c to a first position P1 at which the pawls 41 are positioned when the motor 34 is not operating, a second position P2 at which the pawls 41 become positioned when the engaging sections 41a engage with the inner teeth 50a of the clutch housing 50 through operation of the motor 34, and a third position P3 at which the pawls 41 become positioned on the opposite side to that of the second position P2 across the first position P1 upon operation of the pretensioner 15; and a return prevention mechanism that prevents the pawls 41 from returning to the first position P1 and the second position P2 after having moved to the third position P3.</p> |
