Fastening structure for rotary body and rotary shaft, has two external-thread parts formed at rotary body, with one external-thread part having pitch size smaller than pitch size of other external-thread part

摘要

Two external-thread parts (211,212) are formed at a rotary shaft (210). An internal-thread part (131) is formed at a rotary body (100). The pitch size of the external-thread part (212) is smaller than pitch size of external-thread part (211). The external-thread part (211) is engaged with internal-thread part of rotary body. A nut (213) is bound tight to external-thread part (212) facing the side of rotary body.