Abstract: A synchronous power transmission system and a toothed belt therefor. The belt having convex curvilinear flanks shaped to minimize the generation of unpleasant sound resulting from meshing of such belt with a pulley.

Abstract: A flexible power transmission belt having a plurality of teeth each of which has a pair of arcuate convex flank portions which in longitudinal cross-section closely approximate to an arc of a circle. Each tooth exhibits a height to width relationship within a predetermined range, and the arcuate flanks each have a pressure angle within a predetermined range. The belt is preferably used in combination with a toothed pulley whose teeth are substantially conjugate to the belt teeth and whose cavities between the teeth have a height to width relationship within another predetermined range and have concave flanks exhibiting a pressure angle in still another predetermined range, said belt tooth width being approximately 0.98 of the pulley cavity width so as to provide a high torque positive drive power transmission system having minimum backlash.

Abstract: A toothed positive drive power transmission belt of the type having an endless substantially inextensible tensile member to which the belt teeth are secured, which teeth have a curvilinear cross-section and may be covered by an outer protective fabric or the like. In the body of each tooth is a layer of fabric reinforcement separated from the outer surface of the belt teeth by a cushion layer of soft elastomeric material so that the outer surface is free to flex while the inner portion of the tooth is reinforced against shearing.