| 摘要 |
The present invention relates to a multistage boom which is unfolded in a multistage way and, more specifically, to a multistage boom of a crane in which: a plurality of booms having smaller diameters are successively inserted into a hollow space of a boom having a larger diameter; and a plurality of booms are operated simultaneously or selectively to be unfolded by being drawn out or be folded by being inserted by a linking wire with a cylinder member mounted on the multistage boom. The present invention has effects of: remarkably reducing a separated space formed between a second stage boom and a third stage boom as a first wire, moving through the separated space formed in the hollow space of the second stage boom and outside the third stage boom, is able to convert a direction through a pair of penetration holes installed on one side of the third stage boom; reducing the diameter of the hollow space of the second stage boom and the weight of the whole crane multistage boom caused thereby as the first wire moves and a separated space, capable of converting a direction, can be reduced; and unfolding and using an appropriate boom set in accordance with the weight of an object to be moved or the situation of a crane usage site by building a boom set, for drawing out a multistage boom by the first cylinder and the first wire, with a first stage boom, the second stage boom, and the third stage boom and building a boom set, for drawing out another multistage boom, with a fourth stage boom and a fifth stage boom which are extended from the third stage boom. |
