To increase a lubrication effect of a pin which is slidably engaged with a pin hole of a link plate of a chain.

The pin 13 is relatively rotatably engaged with the pin hole 11a which is formed on the outside link plate 11o of the chain, and four spiral grooves 13b are formed on the outer peripheral surface 13a of the pin 13. Since the pitch P of the adjacent spiral grooves 13b of the pin 13 in the axis A direction is made smaller than or equal to the width Bo of the pin hole 11a of the outside link plate 11o in the axis A direction, a lubrication effect can be increased by placing at least one spiral groove 13b so as to be opposite on an arbitrary busbar on the inner peripheral surface of the pin hole 11a without taking into consideration the phase of the pin 13 at the time of assembling. When the radius of the pin 13 is R, and a relative rotation angle with respect to the outside link plate 11o is θ, the pitch P' of the adjacent spiral groove 13b in the circumferential direction is made smaller than or equal to Rθ. Thus, the lubrication effect can be further increased by making one spiral groove 13b pass all positions within sliding ranges of both the adjacent grooves.

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