Abstract: The invention provides a power transmission device in which the switching mechanism and control operation can be simplified. Different directions are established for the relative rotation in which the first sprag engages the inner race and the outer race, and the relative rotation in which the second sprag engages the inner and outer races, whereby the inner retainer and the outer retainer are caused to move relative to each other about an axial center O by a load imparting device, and either the first sprag or the second sprag can be made to engage the inner race and the outer race. The combined retention of the first sprag and the second sprag by the inner retainer and the outer retainer actuates the load imparting device to allow the power transmission direction to be switched all at once, resulting in a simpler switching mechanism and control operation.

Abstract: The invention provides a power transmission device in which the switching mechanism and control operation can be simplified. Different directions are established for the relative rotation in which the first sprag engages the inner race and the outer race, and the relative rotation in which the second sprag engages the inner and outer races, whereby the inner retainer and the outer retainer are caused to move relative to each other about an axial center O by a load imparting device, and either the first sprag or the second sprag can be made to engage the inner race and the outer race. The combined retention of the first sprag and the second sprag by the inner retainer and the outer retainer actuates the load imparting device to allow the power transmission direction to be switched all at once, resulting in a simpler switching mechanism and control operation.