| 摘要 |
PROBLEM TO BE SOLVED: To carry a jib in a dimension suitable for a road traveling gauge by providing a series of elements mutually jointed around a horizontal shaft on the jig, and constituting these element from at least two relatively long main elements and at least two relatively short chip elements. SOLUTION: A rotating frame 2 is supported on a foundation frame 1 through a directional changing mechanism, and a folding mast 4 consisting of lower and upper mast elements 5 and 6 is jointed around a horizontal shaft. A delivery crane jib 7 is jointed to the top of the upper mast element 6 around a horizontal shaft 8. In such a tower crane, the jig 7 forming the traveling path for a club 9 is formed of a relatively long first main jib element 10, a relatively short intermediate jib folding element 11, a relatively long second main jib element 12, a relatively short jig chip element 13, and a second jib hip element 14 constituting the terminal element of the jib 7. These jib elements 10-14 are integrated by being joined around the horizontal shaft.
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