Patent ID: 8668609

Claim:
An inverted tooth chain drive system comprising: a sprocket comprising a plurality of teeth defined relative to respective tooth centers, said tooth centers spaced evenly in a circumferential arrangement about an axis of rotation, each of said plurality of teeth comprising an engaging flank; an inverted tooth chain engaged with the sprocket and comprising a plurality of rows of links, with leading inside flanks of each row positioned to make initial meshing contact with said engaging flank of one of said sprocket teeth; at least some of said teeth being standard teeth and other ones of said teeth being flank-relieved teeth, with said engaging flanks of said flank-relieved teeth negatively offset relative to their respective tooth centers as compared to said engaging flanks of said standard teeth relative to their respective tooth centers; said plurality of teeth separated from each other by respective root surfaces, and said root surface adjacent and leading each flank-relieved tooth in terms of an intended direction of rotation of said sprocket being a raised root surface located radially outward with respect to said root surface adjacent and leading each standard tooth; wherein: the engaging flank of each standard tooth and the engaging flank of each flank-relieved tooth are contacted by leading inside flanks of a meshing row of the chain when the meshing row makes initial contact with the sprocket; the engaging flank of each standard tooth is contacted by trailing outside flanks of said chain when said inverted tooth chain is fully meshed with one of said standard teeth; and said trailing outside flanks of said chain are spaced from the engaging flank of each flank-relieved tooth when said inverted tooth chain is fully meshed with one of said flank-relieved teeth.