| 摘要 |
A tower crane with composite structure, self-assembling, with sections which are hinged together with the use of horizontal hinges, the whole comprising a load-bearing arm (50) made up of several sections (23), (24), (25), (26) hinged together, and a tower composed of at least one pair of sections (20, 21) hinged together (at 12) and at least one section (22) which can be inserted into or telescoped from one of the other sections, and with tie rods (31, 32, 33) which work with the aforesaid arm (50), which arm comprises a first primary section (23), vertically higher at a front part thereof for connecting to a secondary section (24); a secondary section (24) interposed before a second primary section (25), of uniform height; a third primary section (26), hinged at one end (at 16) of its upper surface to the free end of the second primary section (25); actuating means (60, 62) for unfolding and re-folding of the joints between the primary sections (23, 25, 26); and means (68, 70; 32, 33) for re-establishing structural integrity between the first and second primary sections (23, 25) when the arm is in the deployed position.
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