A new boom system from Leibherr for its LR 1750/2 and LG 1750 lattice boom cranes will help the 750t lifters erect the latest generation of wind turbines that were hitherto the exclusive domain of the 1000t and above crane classes.
The machinery giant said in a statement that the completely new SX system, which is available now, was developed keeping in mind turbines with a hub height of up to 165m and component weights of up to 120t.
The new SX system, which has been tested at Leibherr’s acceptance site, differs from previous boom systems by the use of 3.5m wide lattice sections in the bottom area of the boom, rather than the previous 3m wide ones. The extended lattice sections increase the lateral stability of the boom and deliver a higher load capacity, Liebherr said.
The weight of the lattice sections has also been reduced, enabling the boom length to be raised up to 165m when combining the main boom and the fixed lattice jib. To further increase lift capacity, the SX2 and SX3 systems features a facility to use two lattice sections, each 14m in length, or three lattice sections of the same length respectively, with a width of 6m installed in the lowest area of the main boom, instead of the 3.5m-wide lattice sections. This increased the load capacity of the boom system by increasing its rigidity.
To install the 6m-wide lattice sections in the boom, an extension adapter from 3m to 6m is provided on the pivot section for the turntable. A second adapter reduces the 6m width to 3.5m at the top. With economy as the goal in the design, operators only have to buy the 6m-wide sections and the adapters in addition to the SX system, Leibherr said.
The challenge for the 6m-wide lattice sections was how they could be transported economically on public roads. To meet this Liebherr built the wide boom sections with two halves, which can be bolted together in the centre and separated again quickly. For transport, the individual halves are slightly offset longitudinally and then joined so that they mesh together like teeth, which results in a practical transport width of 3.5m.
The complete SX system can be interchanged between the LR 1750/2 crawler crane and the LG 1750 mobile crane.
