| 摘要 |
PURPOSE:To prevent three nuts from loosening by aligning the outer peripheral surfaces of the head side and intermediate nuts of three nuts to engage peripherally with each other and making them no surface contact with each other axially so that the intermediate nut is pressed axially against the outside nut. CONSTITUTION:A bolt 16 inserted through bolt holes in a fastening plate material 9 and fastened plate material 10 has three lock nuts screwed and fastened thereon. A small gap 20 is formed between a first nut 3 and a second nut 4 so that axial contact pressure is absent between both nuts. While the second nut 4 makes firm surface contact with the fastened plate material 10, the first nut 3 and fastening nut 11 make axial strong surface contact with each other and the first nut 3 and the fastening nut 11 make axial strong surface contact with each other to generate a strong lock effect caused by a double nut of the first nut 3 and fastening nut 11. Thus, the first nut 3 is never loosened. Since the first nut 3 and second nut 4 are fixedly prevented from turn by a locking part 5 so that the second nut 4 is prevented from turning in the loosening direction. As a result, a lock nut having a large effect of preventing the loosening is provided as a whole.
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