| 摘要 |
PROBLEM TO BE SOLVED: To prevent the invasion and attachment of a foreign matter and to easily mount and demount a sprocket by forming a part to be detected on an outer peripheral face of a fastening nut for fastening and fixing the sprocket to a shaft to be driven, and mounting a speed sensor in adjacent to the part to be detected. SOLUTION: A fastening nut 4 fixes a sprocket 3, and also has a function of a sensor rotor in a speed detecting mechanism 1. The mount of the speed sensor 5 to a sprocket cover 6 is adjusted so that a detection part 5a thereof is close to the fastening nut 4. This non-contact type speed sensor 5 detects the number of times of the passages of an apex of the fastening nut 4 as a member to be detected through the detection part 5a, and the speed is detected when four apexes reach the detection part 5a of the speed sensor 5 in a case of the fastening nut 4. Whereby the invasion and attachment of a foreign matter can be prevented without adding a specific component, and the sprocket can be easily mounted and demounted. |
