| 摘要 |
PURPOSE:To prevent a sprocket wheel from being worn and workability from being reduced owing to an increase in the number of replacements of a sprocket and a ring by providing wear-resistant member having a disengagement- preventing means for preventing the members from being removed outwardly in a radial direction. CONSTITUTION:A plurality of teeth 3 radiately arranged with a mounting hole 5 as a center are provided between a pair of annular rims 1, 2 on the right and left sides of a sprocket body 7, and each tooth 3 has a locking recess 4 extending through the rim 1 to form an opening 4a on the side of the rim 1. Further, a wear-resistant member 6 having a shape identical to that of the locking recess 4 is inserted into each locking recess 4. Accordingly, when a saw chain is rotated at a high speed, a drive link D initially impinges against the surface 3a of the tooth 3 on the forward side of a driving direction N to wear the surface 3a. However, after wearing the same, the drive link D is allowed to impinge against the wear-resistant member 6. By this method, since the wear-resistant member 6 is hardly worn even if the drive link D impinges against it, a sprocket wheel wears long. |
