| 摘要 |
PURPOSE:To allow joining of a nut engaging with a support bolt that makes a caster to be rotatably supported on a shaft in a short time by providing a protrusion at the outside of the nut and spot-welding the protrusion to a foot portion. CONSTITUTION:The crosswise cross section of a nut 3 is nearly formed into a rectangle and protrusions 31 to 34 are formed on each end in two parallel sides, respectively. This nut 3 is joined by spot-welding the protrusions 31 to 34 at the inside of a foot 4. As a result of this structure, the nut can be joined in a short time.
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