The improved lifting capacity values resulting from the reinforced lattice booms enables the 750t cranes to lift weights normally reserved for the next higher class of crawler cranes with a 1000t lifting capacity.
Liebherr said the main application for this new development is wind turbine erection. The reinforced system enables the cranes to erect turbines with a hub height of up to 166m. Components with a weight of up to 127t can be assembled at that height using the SX3 version. Depending on the boom system and hoisting height, the new development means an increase in lifting capacity of up to 30%.
The SX system with its 3.5m-wide lattice boom sections can be extended by the SX2 and SX3 versions. With these, two or three 14m-long lattice boom sections with a width of six metres are fitted to the lower section of the main boom. These wide boom sections each consist of two halves, which can be bolted together at the centre.
To transport them, the individual halves are slightly offset longitudinally and then joined so that they mesh together like gear wheels. This ensures a practicable transport width of 3.5m.
The first cranes with the reinforced boom have been in action for several weeks. Hüffermann Krandienst based in Wildeshausen near Bremen received one of the first LR 1750/2 cranes with the SX2 system in May. The crawler crane's first job was at Siggelkow Wind Farm in Mecklenburg Western Pomerania where it erected three Enercon type E-101 systems with a hub height of 135 metres.
Another time-saving feature of the crane when working at a wind farm is the VarioTray. This splitting derrick ballast means that the fully packed ballast tray only required to erect the boom of the crane does not have to be removed for the erection of the wind turbine. Furthermore, it is available at all times for lowering the lattice boom. With VarioTray only the central section of the ballast is unbolted and is then suspended with a maximum of 125t fitted to the derrick boom.
