Patent ID: 7922611

Claim:
A power transmission system provided with a pulley rotatably attached to a casing and a hub provided at a front end of a shaft projecting to the outside from said casing, wherein the hub rotates integrally with said shaft and transmits power from said pulley to said shaft, and wherein said hub is comprised of an inner hub fastened to said shaft, an outer ring arranged at an outer circumference side from said inner hub, and a torque transmission elastic member integrally molded together with said inner hub and said outer ring, wherein the torque transmission elastic member is solid and fills a space between the inner hub and the outer ring, and a gate mark, which is a protrusion and is a mark of an injection gate used for molding of the torque transmission elastic member, which is integrally molded with the outer ring, wherein the gate mark is located on the torque transmission elastic member, is made of the same material as the transmission elastic member, and is formed on a line extending from a front end of said outer ring.