| 摘要 |
PROBLEM TO BE SOLVED: To enable both of disengagement and rotational operations of a gear by a drive of a driving source and to continue power transmission from the driving source to a driven side even when a rotation load or a rotation speed of the driven side varies.SOLUTION: When a reverse driving force Frof a set value of Fsp/tanαor less, which causes a relative rotation of a driving gear 14 engaging with a driven gear 16 with respect to a rotation shaft 12 in a predetermined direction, acts on the driving gear 14 from the driven gear 16, an end face 24b of a screw thread 24a of the driving gear 14 is caught on an attachment face 22e of the rotation shaft 12 so as to suppress movement of the driving gear 14 toward the other side in an axial direction. This allows holding mesh of the driving gear 14 with the driven gear 16 even when the reverse driving force Fracts on the driving gear 14 from the driven gear 16. |
