To minimize a set torque at which a torque limiter limits rotation, to improve the use durability of an inner ring and a coil spring, and to prevent contamination caused by a liquid lubricant at the circumference of the torque limiter.
In the torque limiter A, both ends of the coil spring 3 are locked to an outer ring 2 or a fastening force adjusting ring 4 which rotates integrally with the outer ring 2, and relative rotation is stopped or a rotating force is limited by diameter-contracting or diameter-expanding the coil spring 3 according to the direction of the relative rotation with respect to the outer ring 2 of the inner ring 1. The inner ring 1 is formed of a resin raw material, and a plating membrane 5 containing a wear resistance metal is formed at a contact part contacting with the coil spring 3 at the outside diameter surface of the inner ring 1. Since the inner ring 1 is formed of the resin raw material, the inner ring is reduced in weight, a desired fastening force can be set small accordingly, friction damage caused by a slide between the coil spring 3 and the inner ring 1 is reduced by the lubrication action of the plating membrane 5 which is favorable in wear resistance, and thus the use durability of the torque limiter A can sufficiently be enhanced.
Higashio Masahiro
Takayoshi Tagawa