| 摘要 |
PROBLEM TO BE SOLVED: To easily add supplementarily an insert boom to a boom under assembling both in a condition laid horizontally and in a vertical condition suspended. SOLUTION: An insert boom is provided with the first end part and the second end part, and a male type coupling tool of the second end part of the first insert member 22 is connected to a female type coupling tool of the first end part of the second insert member 23. A base part and a protruded part of the male type coupling tool has an extending part substantially vertical with respect to a longitudinal axial line of the insert boom, and the extending part and the protruded part forms a receiving part. The protruded part of the male type coupling tool is fitted in between two protruded parts with a space in the female type coupling tool. The female type coupling tool has also a coupling tool connected to one protruded part and extended toward the other protruded part, and the coupling tool is fitted into the receiving part of the male type coupling tool. A holding tool connected between the extending parts of the male coupling tools prevents the male type coupling tool from being engaged and disengaged with the female type coupling tool. |
