L68A1 Mast Section Common accidents and preventive measures in the process of tower crane dismantling
The tower crane manufacturer introduces common accidents and preventive measures in the process of tower crane disassembly.
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1. Common accidents
① The accident occurred in jacking oil cylinder operation has been described before, and is repeated here.
② When lifting the boom, the lifting point is not allowed, the boom is not stable due to the wrong selection of the lifting rope, and the lifting rope is separated from the hook, resulting in a fall accident.
③ The wrong binding method of the steel wire rope causes the steel wire rope to hang on the connecting pin of the pull rod during the process of lowering the pull rod, and the pull rod suddenly loses weight due to the neutral action, resulting in a large swing of the tower crane and a collapse accident.
④ When installing the tower cap or balance arm, the crane fails to tilt up or down according to the regulations, resulting in the tower top leaning backward and causing an accident.
⑤ Dismantling: the key points are dismantling methods, procedures, auxiliary mechanical tools, organization and deployment of labor force, environmental state, disassembly, transportation and demobilization of protection and components, etc.; the requirements for the preparation of dismantling and installation plans are the same, which must be specific and clear.
⑥ Do not strictly follow the disassembly procedures, especially when disassembling the counterweight, first dismantle the boom, then dismantle the counterweight, resulting in the tower crane center moving backward and overturning.
2. Preventive measures and methods
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① Before removing the connecting cross pin between the boom root and the tower body transition section, the tower body and the forearm root shall be tightened with steel wire rope of Ф 12.5mm or Ф 25mm. When the boom is smoothly separated from the rear of the tower, the steel wire body can be removed or the boom can be lowered (the same with the balance arm). The distance between lifting points l shall meet the following requirements: 8m ≤ L ≤ 15mm, and the included angle of steel wire rope shall not be greater than 90o generally. During installation, the position of lifting point under the condition of boom and balance shall be made and the permanent standard position shall be made (the luffing trolley shall be locked at the root and the position mark shall be made) or the lifting point shall be strictly in accordance with the instructions. Especially in the construction, the boom needs to be increased or decreased naturally, which should be paid more attention to
② Generally, the steel wire rope is bound by a 9-11m "Walking Horse" with a length of Ф 22.5MM, so that when the pull rod is lowered, the steel wire rope can slide down naturally to the specified position along the connection of the pull rod.
③ When installing the tower cap or balance arm, work in strict accordance with the requirements of up or down angle specified in the instructions. Before removing the counterweight and the balance arm of the boom, the slewing ring must be connected with the standard section with bolts or pin shafts before operation. It is forbidden to remove the boom without removing the counterweight. Keep a corresponding counterweight in strict accordance with the instructions. In addition, it is not allowed to suspend the balance arm overnight when the boom is disassembled.
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