| 摘要 |
PROBLEM TO BE SOLVED: To prevent a fixing member of an extension beam from being lost.SOLUTION: A fixing member holding part for holding a fixing member of an extension beam is positioned below the extension beam located in a folding position. The fixing member of the extension beam is prevented from dropping from the fixing member holding part by placing an upper surface of the fixing member of the extension beam, which is held by the fixing member holding part, so as to face a lower surface of the extension beam located in the folding position. |
