Liebherrs take centre stage

Two Liebherr top slewing tower cranes are setting the scene at the world's largest open-air opera theatre.

The towers and jibs of the 550 EC-H 40 FR.tronic and 280 EC-H 12 Litronic will form a giant frame enclosing the Bregenz Lakeside Theatre, on Lake Constance, throughout the 2009/2010 season.

They have also been given the role of lifting scenery, weighing up to 12 tonnes, as the drama unfolds during Giuseppe Verdi's opera Aida, premiering on 22 July. Both cranes have been mounted directly next to the stage in the water on timber piles driven into the bed of the lake to form the foundation for the crane structure. The undercarriage of both cranes rests on them.

The 550 EC-H 40 FR.tronic is erected on an undercarriage measuring 10 x 10 m, with a hook height of 59.5 m. Working radius is 54.5 m and the load capacity is 40 tonnes. The 280 EC-H 12 Litronic has an undercarriage of 6 x 6 m and a hook height of 39.4 m. Working radius is 28.5 m and capacity is 12 tonnes. To ensure the parts are carried smoothly and quietly into position, the cranes have two trolleys and a traverse.

A Liebherr A 71 K fast-erecting crane has been installed at the theatre since 2000 for setting backdrops. The 71 K is mounted on a 15 x 13 m pontoon and is set up to work despite movements caused by the water, said Liebherr.