Abstract: A power transmission toothed belt drive having a belt tooth power transmission surface defined by an arc having a radius centered on a point approximately one-half the belt tooth pitch from the centerline of the tooth. The pulley groove has a sidewall surface which confronts the power transmission surface of the belt tooth centered on the same point when the belt tooth is fully meshed with the pulley groove in the operation of the drive. A relatively small clearance with the pulley is provided adjacent the belt tooth root and a relatively large clearance is provided between the pulley groove inner surface and the tip surface of the belt tooth. In one form of the invention, both the power transmission surface and tip surface of the belt tooth are defined by a single radius and the confronting pulley groove sidewall surface and inner surface confronting the belt tooth power transmission surface and tip surface have a constant clearance therewith and are defined by continuous circular arcs.

Abstract: A power transmission toothed belt drive having a belt tooth power transmission surface defined by an arc having a radius centered on a point approximately one-half the belt tooth pitch from the centerline of the tooth. The pulley groove has a sidewall surface which confronts the power transmission surface of the belt tooth centered on the same point when the belt tooth is fully meshed with the pulley groove in the operation of the drive. A relatively small clearance with the pulley is provided adjacent the belt tooth root and a relatively large clearance is provided between the pulley groove inner surface and the tip surface of the belt tooth. In one form of the invention, both the power transmission surface and tip surface of the belt tooth are defined by a single radius and the confronting pulley groove sidewall surface and inner surface confronting the belt tooth power transmission surface and tip surface have a constant clearance therewith and are defined by continuous circular arcs.