The trolley case is a necessity in daily life. The shaking of the pull rod tube of Lichuang bag is scientific. The pull rod is composed of multiple sections, which can be expanded and retracted according to the height required. In order to ensure the smooth use of the pull rod under the condition of thermal expansion and cold contraction, there must be a certain gap between each section of the pull rod tube. If the rod does not shake, there will be hidden danger. The gap is small, the friction force is relatively increased, and the pull rod will not shrink Flexible, easy to jam each other, affecting the service life.
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