Mega strong

At the beginning of September, work began on erecting a 6.2-megawatt wind turbine using the LR11000 crawler crane. The hub of this gigantic wind harnessing machine is around 124 metres high. The turbine is being constructed in the North German onshore test centre for off shore wind farms in Neuenwalde.

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From the very first preparations for the operation in Neuenwalde, it was easy to see that a difficult task lay ahead: For example, 42 heavy transporters were needed to transport the LR11000 to the construction site. While the ballast weights, each weighing 12 tons, appeared to be relatively manageable, it quickly became clear from the combined weight of the crawler mechanisms – 120 tons – just how sizeable the difficulties were that needed to be overcome. Transporting the enormous high-tech steel structure to the site was the first challenge: “The crane came straight from being used on a construction site in Romania,” says Günther Wimmer from Felbermayr’s Project division, explaining the logistics chain. “After the initial leg on the road, the parts of the crane were loaded onto a cargo ship in Constan_a and transported to Bremerhaven. The components were then shuttled to the construction site 42 kilometres away. It took four transport units six days to do it.”

Giants standing shoulder to shoulder

Work began on putting the LR11000 together in the PDW3B configuration in mid- September and, after about a week, the crane was ready to start lifting. This configuration employs to a 78-metre-long “power boom” for increasing the crane’s load capacity, in conjunction with a 42-metre-long derrick boom and a 66-metre-long luffing jib.

The ballast assembly comprises a 435-ton suspended ballast, a 50-ton central ballast and a 210-ton superstructure ballast. When put together in this way, the crane reaches a hook height of 138 metres. The actual lifting work started with placing the fi ve steel towers, which each weighed up to 174 tons.

This was followed by the 194-ton lower section of the machine housing. “This didn’t include the technical components , such as the transformer, gearbox and drive train, which weighed up to 73 tons each and had to be lifted into position separately,” explains Wimmer. The assembly of a helicopter landing pad around 130 metres high concluded the lifting work for the time being.

The grand fi nale – that is to say, assembling the rotor – took place in December. This saw three 74.4-metre rotor blades being fi tted onto a star-shaped head while still on the ground. The 175.4-ton object was then lifted to a height of 124_metres. Painstakingly fi tting the rotor to the nacelle required expert skill and technical perfection: “Once you think about the fact that the head is 152_metres in diameter, it soon becomes clear just how skilled the crane driver and assembly workers had to be,” says Wimmer respectfully, delighted by the operation’s success.