Patent ID: 7993227

Claim:
A hub for use in a power transmission apparatus, comprising: an inner hub having a rigid body; a cylindrical portion having an elastic body formed on an outer periphery of the inner hub; an outer ring including an outer ring body formed cylindrically on the outer periphery of the cylindrical portion, a plurality of protrusions each protruded axially rearward from the corresponding one of the positions in peripherally spaced relationship with each other on the outer ring body and a plurality of tongue-shaped reinforcing portions each protruded radially inward from the peripheral end of the corresponding one of the plurality of the protrusions; and a hub-side engaging portion formed of an elastic body along the protrusions from the cylindrical portion and adapted to engage a pulley-side engaging portion; wherein the distance from the point where a rear-side end surface of the cylindrical portion and the hub-side engaging portion are connected with each other, to a rear-side end surface of the reinforcing portions is a, and the distance from the rear-side end surface of the reinforcing portions to a radially innermost front-side portion is b, then the distance b is less than one half of the distance a.