Abstract: A one-way clutch structure includes: a pair of clutch members disposed between an output shaft and a drive shaft so as to oppose each other in an axial direction; and an engagement element interposed between these clutch members. When a rotation speed of the output shaft exceeds a rotation speed of the drive shaft, the engagement element engages with the clutch portion to connect the output shaft and the drive shaft so as to be integrally rotatable. When the rotation speed of the output shaft becomes lower than the rotation speed of the drive shaft, the engagement of the engagement elements is released to cut off connection between the output shaft and the drive shaft.

Abstract: A one-way clutch includes shafts 56 and 58 projecting from both ends in the axial direction of a planetary gear 44 or 46; and bearing recesses 60 and 62 formed on both end walls in the axial direction of a gear receiver 40 or 42 in such a manner as to be released on the outer peripheral side of an inner member 20 so as to receive the shafts 56 and 58. The fitting between the shafts 56 and 58 and the bearing recesses 60 and 62 allows a circumferential displacement of the planetary gear 44 or 46 within a predetermined range with respect to the inner member 20, the displacement being required for fitting to or releasing from a lock edge 52 or 54, so as to prohibit the planetary gear 44 or 46 from being displaced inward in the radial direction of the inner member 20.