| 摘要 |
A power transmission device comprises a stationary housing rotatably supporting an input and an output shafts and a cylindrical member having a circumferential protrusion. The cylindrical member is coupled on the output shaft and connected to the input shaft in such a manner that the cylindrical member rotating relative to the output shaft is axially moved. A first and a second one-way clutches are fixed to an inner surface of the stationary housing in such a manner that their inner races are rotatable in opposite directions and the circumferential protrusion of the cylindrical member is located therebetween. When the input shaft rotates relative to the output shaft in the direction same as the rotation direction of the inner race of the first one-way clutch, the cylindrical member axially moves to come in a friction contact with the inner race of the first one-way clutch so that the rotational force of the input shaft is transmitted to the output shaft through the cylindrical member, and when the input shaft rotates in the direction same as the rotation direction of the inner race of the second one-way clutch, the cylindrical member axially moves to come in a friction contact with the inner race of the second one-way clutch so that the rotational force of the input shaft is transmitted to the output shaft. |
