Patent ID: 7914409

Claim:
An oil-free chain comprising: pairs of inner plates and pairs of outer plates in alternating, overlapping relationship along the length of the chain, said inner plates having outside surfaces and inside surfaces and said outer plates having outside surfaces and inside surfaces; a pair of bushings for each pair of inner plates, ends of the bushings being press-fit into bushing holes in the inner plates, and each bushing having inner and outer circumferential surfaces; a roller rotatably fitted on each of said bushings, each roller having an inner circumferential surface; and a pair of connecting pins for each pair of outer plates, ends of the pins being press-fit into pin holes in the outer plates, each pin having an outer circumferential surface and extending through, and fitting rotatably in, one of said bushings, and connecting the pairs of inner plates and pairs of outer plates in said alternating overlapping relationship; wherein lubricating oil is sealed between the outer circumferential surfaces of the connecting pins and the inner circumferential surfaces of the bushings through which the connecting pins extend, and between the outer circumferential surfaces of the bushings and the inner circumferential surfaces of the rollers; wherein each said bushing has end portions protruding from outside surfaces of said inner plates, and fitting into recesses formed in the inside surfaces of said outer plates; wherein each said roller has end portions fitting into recesses formed in the inside surfaces of said inner plates; wherein each said inner plate has a bulged portion coaxial with each said recess in its inner surface and extending from its outer surface; and wherein each said outer plate has a bulged portion coaxial with each said recess in its inner surface and extending from its outer surface.