Patent ID: 7128673

Claim:
A chain drive comprising a sprocket and a roller or bushing chain in mesh with the sprocket, the sprocket having a plurality of teeth separated by tooth grooves each of which is formed by facing tooth faces connected to each other by a tooth gap bottom, wherein the rollers or bushings of the chain are engaged with the grooves, and the form of each tooth of the sprocket has a portion where a minimum distance, on the tooth head side of the pitch circle, from at least one point, spaced radially outward from the pitch circle, on a tooth center line, which connects the rotation center of the sprocket and the center of the tooth, to a tooth surface on the front side in the rotational direction of the sprocket, is equal to or greater than the distance, in the pitch circle, between the tooth center line and the front surface of the tooth, in which the diameter of the tooth gap bottom circle of the sprocket is smaller than the diameter df of the tooth gap bottom circle in another sprocket of a roller chain drive comprising a chain having the same chain pitch p and the same roller or bushing outer diameter d 1 , wherein said another sprocket has the same pitch circle diameter d, the same number z of sprocket teeth, a tooth surface radius re, and a tooth gap bottom arc having a radius ri, and wherein, in said another sprocket: d=p/sin( 180 °/z ), df=d−d 1, re (max)=0.12 d 1( z+ 2), ri (min)=0.505 d 1, re (min)=0.008 d 1( z 2 +180), and ri (max)=0.505 d 1+0.069( d 1) 1/3 .