Patent ID: 8888631

Claim:
A chain transmission, comprising: a chain comprising pairs of opposed inner link plates and pairs of opposed outer link plates, connecting pins connecting said pairs of link plates in an alternating, overlapping relationship, and a set of sprocket tooth-engaging elements, each surrounding one of said connecting pins, wherein the link plates of each pair of opposed link plates are spaced from each other by an inner link plate spacing distance that is uniform for all the pairs of opposed inner link plates of the chain; and at least one driven sprocket engaged with said chain and at least one driving sprocket engaged with said chain, each of said sprockets having a perimeter and an axis of rotation; wherein at least one of said sprockets comprises: a set of standard sprocket teeth arranged on the perimeter of said at least one of said sprockets, each of said standard sprocket teeth having opposite side faces both disposed substantially in planes to which the axis of rotation of said at least one sprocket is perpendicular, said standard sprocket teeth having a uniform first face width, measured between said opposite side faces in a direction parallel to the axis of rotation of said at least one of said sprockets, said first face width being smaller than said inner link plate spacing distance and each of said standard sprocket teeth being capable of entry between opposed, spaced, inner link plates of said chain and engaging sprocket tooth-engaging elements of said chain while restricting side slip of the chain by contact between said side faces of the standard sprocket teeth and said inner link plates; and a set of narrow sprocket teeth also arranged on the perimeter of said at least one of said sprockets, said narrow sprocket teeth also being capable of engaging sprocket tooth-engaging elements of said chain, each of said narrow sprocket teeth having a opposite side faces and a second face width measured between its said opposite side faces in a direction parallel to the axis of rotation of said at least one of said sprockets, said second face width of each of said narrow sprocket teeth being narrower than said first face width of said standard sprocket teeth; the opposite side faces of said narrow sprocket teeth being disposed between said planes in which the opposite side faces of the standard sprocket teeth are disposed, whereby, when the narrow sprocket teeth engage sprocket tooth-engaging elements of said chain, contact between the opposite side faces of said narrow sprocket teeth and the inner link plates of the chain is prevented by the restriction of side slip of the chain resulting from contact between said side faces of the standard sprocket teeth and said inner link plates of the chain.