The general principle of the chain of this invention is disclosed in U.S. Pat. Nos. 4,005,609 and 4,078,442 on variable speed drives, issued to the present inventor. This specification discloses and claims its application to articulating link drive chains of the type defined in the American National Standards Institute publication B29.2-1957 (R1971) as "Inverted Tooth (Silent) Chains." The Links of these chains, essentially are operatively distinct from roller type chains only in having projecting teeth instead of rollers for engaging the teeth of drive sprockets.
Early forms of these chains used link pivotal means comprising round holes in the overlapping link ends interconnected by close clearance round pins, the bearing action of the links on the pins simulating that of a simple journal. The effective transverse bearing width of the joints of these chains was thus limited to half the overall chain width. The limited power transmission capacity and durability of this method of chain construction was later improved upon by adding pairs of segmental bushings, bridging the gap between transversely aligned, overlapping link ends, thus extending the link bearing on the pins continuously across the full width of the chain and constituting a three-part joint. This doubled the effective bearing area of the links on the pins while still retaining the characteristic journal bearing action. Effective lubrication of the concentric bearing surfaces of the joints of such chains under load was difficult. Development thus moved toward friction reducing joint constructions utilizing pairs of pins having opposed, convex surfaces in rocking contact with each other. Latterly, the design of these chains has tended towards use of such two-part rocker joint configurations and link apertures of more complex form and increased manufacturing cost. The current development trend thus may be considered to be away from design simplfication and manufacturing economy.