| 摘要 |
PROBLEM TO BE SOLVED: To provide a jib crane and its raising/lowering method, capable of reducing a moment acting on the vicinity of a boom foot when raising or lowering the jib crane. SOLUTION: This jib crane 300 includes: a lower traveling body 301; an upper turning body 302 turnably mounted on the lower traveling body 301; a boom 303 hoistably mounted to the upper turning body 302; boom hoising means 305, 308, 316 hoisting the boom 303; a jib 304 hoistably mounted at the end of the boom 303; and jib hoisting means 310 to 314 hoisting the jib 304. When the boom 303 and jib 304 are raised from the condition in which they stretch on the ground, a supporting member 400 is interposed between the intermediate part of the jib 304 and the ground, and the intermediate part of the jib 304 is supported from the ground. Then the boom 303 is raised. COPYRIGHT: (C)2009,JPO&INPIT
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