LG 1750

The first Liebherr LG 1750 lattice boom crane has erected what is claimed to be the tallest wind power plant in the world, the 5MW Repower company plant close to Brunsbuttel in the North of Germany. Each rotor blade is 61.5m long and weighs 18, and the hub height is 120m. When it begins operation, the plant will generate 17 million kilowatt-hours per annurn and ultimately supply 4,000 homes with current in the Elbe harbour.

The LG 1750, launched by Liebherr at the Bauma show in Munich in the spring, is an eight-axle mobile crane of 96t weight. It arrived at the job site in Brunsbuttel in a convoy of 48 low loaders. The heaviest component in the wind power plant weighed 170t, and this section had to be positioned at 26m radius and a height under hook of around 85m. The crane handled this load-case with the 105m long lattice boom and the 42m derrick boom. For the last three big lifts - top tower section, machinery deck, and blade star - the four-man Nolte team extended the boom to 122m and mounted to it an off-set 12m jib. Because of the high set-up of the basic equipment - the slewing ring is already situated at a height of nearly 5m ­ Liebherr said that this way it was possible to attain a pulley head height of 135m.

The last part of the tower was erected in this configuration. Again at a radius of 26m, the crane positioned the steel cylinder of 40m and thus completed the tower of 115m. The crane also positioned the machinery deck, which weighed 142t, was 18m long, and 6m high. The machinery deck was completed with other components such as power train, generator and deck crane before the giant blade star with its 126m rotor diameter could be assembled on the ground. An anemometer on top of the crane continuously signalled to the 25-man site erection team gusts with wind speeds of up to 9m per second. This was too much to lift the propeller so it was suspended on the hook of the LG 1750 for several hours. Late in the evening, the wind conditions allowed the three-blade hub to be lifted to a height of 120m. Illuminated by spotlights, the blade star was bolted to the machinery deck, and the windmill completed.

Source: Cranes Today

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