Liebherr LR 11350-P1800 crawler being used to lift the nacelle of a 6 MW wind turbine in the Netherl

Liebherr LR 11350-P1800 crawler being used to lift the nacelle of a 6 MW wind turbine in the Netherlands

A 1,350 tonne Weldex Liebherr LR 11350-P1800, equipped with the manufacturer's new parallel boom, has lifted the 340 tonne nacelle of a 6 megawatt wind turbine.

The Repower nacelle was lifted in a complete assembled state to the top of the 110 m tower in Eemshaven, the Netherlands. The gross weight of the lift was 378 tonnes.

Repower said, as far as it was aware, this was the first time a complete nacelle of this weight had been lifted by one crawler crane in a single hoisting operation. Usually, the drive train and other components are lifted individually once the housing has been lifted and positioned, added the company.

The main advantage, said Liebherr, was the amount of time saved because components no longer need to be assembled at a great height. The lifting times are also shortened, meaning there are fewer waiting periods when the wind becomes too strong. "We could, of course, also have carried out the assembly of this machine housing with an LG 1750, but then we would have needed several lifts, and several more days to do it," said Simon Langefeld, Repower site team leader.

This was proven correct on the Repower project, added Langefeld, because after days of waiting in strong wind conditions the site team had a narrow window of time to lift the nacelle.

"Just as the machine housing, 18 m long and seven metres high, was being secured, the wind gauge on the boom tip of the crane was already showing that the wind was getting up again. It will be another few windy days before the rotor hub and the blades can be put in place," said Langefeld.

The P-Boom was originally developed by Liebherr for the 300 tonne capacity LR 13000 crawler, but it was decided to add the innovation to the smaller LR 11350. "The load capacities can be very clearly seen from the example at Eemshaven. With the boom at a steep setting and a mast length of 144 m, the lifting values with the parallel boom are more than 70% greater in comparison to the conventional single lattice boom," explained a Liebherr spokesman.

Two 6 MW systems were installed by the LR 11350-P1800 at the site, for testing purposes. There are plans for 48 turbuines of this type to be installed from 2013 in the North Sea East offshore windpark, off the island of Heligoland.

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