| 摘要 |
PROBLEM TO BE SOLVED: To improve the inspection workability by easily and efficiently detecting looseness of a screw. SOLUTION: A support bar 14 is installed between handrails 13, and a lower end part of a detecting rod 24 supported by the support bar 14 is inserted into a cleat 1a of a footboard 1, and when the screw 2 loosens and projects from a bottom part, the detecting rod 24 is rotatably displaced by abutment of the screw 2.
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