Mammoet pair on 600 tonne portal

Netherlands-based international lifting and transport specialist Mammoet has been using its two 1,200 tonne capacity Liebherr LTM 11200-9.1 wheeled mobile cranes around Europe for about six months. Earlier this year they were got together for the first time for a series of five tandem lifts at Cuxhaven. The job was to erect a 600 tonne capacity portal crane with a total weight of 1,000 tonnes.

At Steel Construction GmbH near Cuxhaven they build foundation systems for offshore wind farms. A heavy load handling quay is being built to load the 490 tonne tri-piles onto barges.

The heaviest loads were the two 250 tonne main bridge members nearly 70 m long and 5 m tall suspended from the two crane hooks. The cranes had to be repositioned so being able to move with all 52 tonnes of counterweight on the superstructure saved time.

The final and most challenging lift was to install the 155 tonne travelling trolley with machinery house at a height of 50 m. The 30 x 6 x 6 m load had to be lifted, rotated 90 degrees and positioned on to the tracks on the two crane bridge beams.

To make this lift one of the cranes had to reach over the erected crane's structure to pick the load at a 23 m radius. It was erected with the 50 m boom and 30 m luffing fly jib. The other crane had the 100 m boom and Y-suspension system. Clearance for the boom of 3 m and the wind speed increasing during the lift made it a delicate task.