To simplify the assembly by providing a roller connected with a rotary shaft for rotation and an output mechanism provided with an output shaft connected in a part other than a connection part, making the output shaft eccentric centered on the rotary shaft, and fixing a position of the output mechanism.

When a rotary shaft 56 rotates in the arrow direction, a roller 61c begins to rotate, is brought into pressure-contact with a rotary cylinder 62 and the rotary shaft 56, and moves in such a manner that it is nipped in a wedge angle M. Consequently, rollers 61a, 61b come into pressure-contact with the rotary shaft 56 to start their revolutions centered on pins 60a, 60b. The rotary cylinder 62 in contact with outer peripheries of three rollers 61 begins to rotate in the arrow direction due to friction force and is connected when rotation speed of the rotary shaft 56 is higher than that of an output shaft. When the rotary cylinder 62 rotates at a higher speed than that of the rotary shaft 56, the roller 61c starts to move in the direction in which pressure-contact of the rotary shaft 56 and the rotary cylinder 62 is shut off because there is no pin which becomes a central shaft in the roller 61c and operates so as to shut off the power transmission. Consequently, simple adjustment is possible by eccentrically centering a position of the output shaft on the rotary shaft.