PURPOSE: To facilitate the changeover of manual-electric by providing a linking means for performing the connection and separation of the 1st and 2nd clutch movable members, and also a means to move or engage the movable members of these two clutches.

CONSTITUTION: When a motor 5 is driven, a follower shaft 4 is driven in rotation through an electro motion drive shaft 7 and the 1st clutch 9, and an output shaft is rotated. Next, a handle 6 is rotated in order to bring a manual drive condition, and then, a manual motion drive shaft 8 is rotated, and a cam 20 is rotated, and a protruding portion 19 is pushed, and the 2nd operation ring 12 is moved to the side of the follower shaft 4, and the movable member 10a of the 2nd clutch 10 is moved to a connection position, and the rotation of the shaft 8 is transmitted to the shaft 4 through the clutch 10, and the output shaft is rotated. As the ring 12 is being moved, the 1st operation ring 11 is moved against the energizing force of a spring 13, and the movable member 9a of the clutch 9 is moved to a separation position, and the clutch 9 is separated, and a drive condition by means of the motor 5 is cut off. Also, the manual drive condition is retained by the projection of an engagement claw 17.