Abstract: Coupling members (50) are inserted into through-holes (9 and 10) in links (2) of a chain (1). The coupling member (50) includes first and second pins (3 and 4). Pairs of end portions (14 and 15, 27 and 28) of the first and second pins (3 and 4) with respect to an orthogonal direction (V) orthogonal to both a chain travel direction (X) and a chain width direction (W) are received by receiving portions (38 and 39, 40 and 41) provided to the corresponding through-holes (9 and 10) in the corresponding links (2). At least one of the end portions (14, 15, 27, and 28) includes a curved surface portion (14, 15, 32a, or 32a) received by the corresponding receiving portion (38, 39, 40, or 41). The curved surface portion (14, 15, 32a, or 32a) includes an apex portion (20, 22, 33, or 33) with respect to the orthogonal direction (V), and the curvature radius of the curved surface portion (14, 15, 32a, or 32a) is increased continuously or step by step as headed toward the apex portion (20, 22, 33, or 33).

Abstract: A chain is made by connecting a plurality of link modules. Each link module includes first to third link units adjoining in a chain advancing direction. Each of the first to third link units includes seven links arranged in a chain width direction. The links are arrayed sequentially in the following order from one end with respect to a chain width direction, if the links of the first link unit is expressed by “1”, if the links of the second link unit is expressed by “2” and if the links of the third link unit is expressed by “3”: [1, 3, 2, 2, 3, 2, 1, 3, 2, 1, 3, 2, 1, 3, 2, 1, 3, 1, 1, 3, 2].

Abstract: At the peripheral edge of a through hole, in which one pin or strip in a link plate is fixed, a compressive residual stress is applied selectively to vicinities of the outer corners of two upper and lower sides confronting in the chain radial direction of said one pin or strip.

Abstract: An endless loop-like chain 1p consists of a plurality of link plates, laminated, that are linked to be freely bendable by pin members. The endless loop-like chain 1p is looped over each of the upper rollers and a lower roller to make up a polygon. If the chain is rotated endlessly while a tension load is imposed on the chain by each of the rollers, a pretensioned chain is obtained.

Abstract: A chain includes a plurality of links arranged in the chain-running direction and a plurality of connecting members connecting the links. A substantial plane strain state is applied to the stress field in the links created when the chain looped around pulleys is driven.