Tall ship cranes8 December 2008
Potain and Liebherr have both recently supplied giant tower cranes to shipyards.
In South Korea, Daewoo Shipbuilding has bought three large tower cranes from Liebherr, including a 3150 HC 70, a 4000 HC 80 and a 4000 HC 100. At the time of its delivery, earlier this year, the 4000 HC 100 was the largest crane Liebherr Biberach had ever built. The crane has a load moment of 4,000tm, a working radius of 96m and a height under hook of 75m.
The crane is being used to hold components weighing up to 100t while they are welded into place. At the end of the jib, the crane can lift 23.5t. The crane is large enough to multi-task: its 96m radius means it can work on two large ships in adjacent berths at the same time. It has been mounted on a mobile gantry, allowing it to travel between ships at a speed off 40m/min.
The crane weighs 740t without ballast; with full ballast the overall weight is 970t. Despite its giant scale, Liebherr was able to make use of its experience with smaller cranes. Liebherr says, “The technical know-how available for project planning, development, and the design and manufacture of the individual components was of particular importance. Liebherr benefited from the modular system for steel construction, which was partially available even for cranes as large as these. Another major advantage was the range of skills available for the conception and construction of the drive units and control systems required. These, like many other components, traditionally come from Liebherr’s own development and manufacturing resources.”
One component that needed to be designed specially for the crane was a new hook block. This has been designed for re-reeving from two-line to six-line operation. The six-line option allows the crane to lift its maximum 100t load.
More than 5,500 miles away, a shipyard in Dunkirk, France, is also using a giant tower crane. At the Port Autonome de Dunkerque, subcontractor ARNO repairs more than 250 ships a year for clients including the Belgian navy. Manitowoc's special application cranes division was chosen to build a 50t capacity Potain MD 1100 tower crane for the site. The crane has a 60m jib and under hook height of 56.3m. At the end of the jib, it can lift 13.8t.
The design of the shipyard shares more in common with those in the US than in Europe; it was built with US assistance after World War II. This meant the design team needed to make more changes than normal to the Potain crane chosen. Most significant of these changes was the design of a 10.7m x 10.7m portal, to allow the crane to travel on the 500m track running around the dockside.
Gerard Vezant, sales director for special application cranes at Manitowoc, says, “Each special application crane we build is adjusted to specific requirements, but on this crane we made more changes than ever before. Our ability to deliver to the client’s needs within a relatively short timeframe helped us win this contract. Didier Delorme, our business manager, was in constant communication with the people in Dunkirk making sure every commitment was met. And at our design office, Jean Claude Gateau oversaw all technical changes.”