Patent ID: 8888633

Claim:
A low frictional sound silent chain, comprising: rows of link plates, each being bifurcated to form a pair of teeth each having a tip and a root, each of said rows of link plates being interleaved with two other rows of link plates and connected thereto by connecting pins, whereby teeth of the link plates in each row overlap teeth of the link plates in an adjacent row; wherein said teeth have inner and outer flanks; wherein the inner flank of each of said teeth is composed of an engagement starting region adjacent the tip of the tooth, the engagement starting region being in the form of a circular arc having a constant radius, and a straight engagement guiding region extending from the engagement starting region to the root of the tooth, the root being spaced from said circular arc; wherein said inner flanks are shaped so that, when any part of the chain is straight and under tension, the engagement starting regions and the straight engagement guiding regions of the inner flanks of the teeth in said part of the chain protrude beyond the outer flanks of overlapping teeth in an adjacent row in said part of the chain, whereby, as the chain engages with a sprocket, inner flanks of the link plate teeth engage the sprocket teeth and thereafter outer flanks of overlapping teeth in an adjacent row come into engagement with the same sprocket teeth; and wherein the inner flanks of each link plate of the chain are shaped so that, even when a link plate of the chain is inclined slightly forward as a result of chordal action, the engagement starting region and the straight engagement guiding region of its forward inner flank are disposed so that the engagement of the inner flank with a sprocket tooth starts at the engagement starting region and continuously shifts from the engagement starting region to the straight engagement guiding region as said sprocket rotates.