| 摘要 |
PROBLEM TO BE SOLVED: To prevent the deterioration of effect of grease by suppressing the scattering of the grease.SOLUTION: A circumferential wall 121, which surrounds the outer circumference of a ratchet member 110 that is rotated integrally with a second pinion 42, is provided on a second gear 41, which is provided coaxially with the second pinion 42. An accommodation chamber 120 of a cylindrical shape having a bottom, which accommodates the ratchet member 110, is formed inside the circumferential wall 121. A ratchet mechanism 100, which is structured with engagement pawls 113 of the ratchet member 110 and engagement teeth 122, which are provided on the inner circumference of the circumferential wall 121 and with which the engagement pawls 113 engage elastically, makes the second pinion 42 and the second gear 41 to at least one of which grease is applied, rotate relatively while making the engagement pawls 113 engage with and disengage from the engagement teeth 122. In this ratchet, engagement and disengagement of the engagement pawls 113 to the engagement teeth 122 are carried out in a space formed by closing an opening of the accommodation chamber 120 with a cover 150. |
