The massive stage that the rock band U2 performs on in its current world tour relies on an innovative synchronous lifting system designed and built by Enerpac, a Glendale-based division of Actuant Corp.
"The Claw" is one of the largest stages to be included in any rock tour and includes a central grid that towers over the band and its audience. It weighs more than 200 tons and many of U2’s performances are inside stadiums where cranes cannot fit.
The band needed a unique solution to move the specialized stage into place.
"Stageco (a Belgian firm hired to build the stage) required a system that could lift the huge stage, was flexible enough to allow for quick assembly and disassembly, and met extensive safety criteria," said Mark Sefcik, president of Enerpac. "The nice thing about this is that it is small enough to travel with the stage so they can have the same equipment there each time."
Because "The Claw" is so large and takes so much time to set up and tear down, the band ordered three identical stages. Enerpac’s units are integral components to all three stages.
Enerpac’s hydraulic lifting system uses a stair-stepping method that locks the stage in place at multiple stages, which allows for synchronization and improved safety. The lifting system uses four hydraulic pumps, one located in each of the four towers pushing the stage upward.
"What we do not want to do is to not have it lift synchronously," Sefcik said. "If you put any torsion on it, you’ll break it. We want to lift this precisely and to slowly walk it up in a controlled fashion."
The same system is installed as the stage is disassembled, Sefcik said.
"When the time comes to bring the stage down, we walk it down in the same method we used to bring it up," he said.
Enerpac has developed similar projects to lift the Golden Gate Bridge in San Francisco for repairs, position the Millau Viaduct in France and lift the roof onto the "Bird’s Nest" Olympic stadium in Beijing, China.
Enerpac’s engineers in the Milwaukee area, Spain and China developed a software system to coordinate the hydraulic system, Sefcik said. The hydraulic systems were assembled in Europe.
The company’s engineers all over the world have assisted Stageco’s workers and other U2 tour officials setting up the stages all over the world.
"When they were in Chicago, we responded to them and helped instruct the people that were here," Sefcik said. "We’ve had local folks in Europe and (the U.S.) do the same thing.”
