A flexible frame7 November 2019
A Liebherr LR 11000 crawler crane featuring the highly flexible “V-frame” ballasting system has successfully completed its first jobs in the field.
The 1,000t crane operated by Swiss crane logistics contractor Emil Egger used this hydraulically adjustable folding frame for the suspended ballast to complete a bridge hoist near Lausanne and also removed an old fire ship from the River Rhine in Basel.
The bridge site at Moudon in western Switzerland featured everything that could make a crane job more difficult— extremely restricted space, protected trees and a heavy bridge which had to be positioned over a river with a 180° slewing process by the crane with a large radius and therefore also a large suspended ballast radius.
The demanding requirements on site therefore created perfect conditions for a stiff practical test for the first use of the new V-frame on the LR 11000. “Without the hydraulically adjustable ballast radius, hoisting the bridge would have been significantly more expensive,” said Michael Egger, managing director at Emil Egger.
“Firstly, it would have required much more expensive work on the embankment to get closer to the abutments with a crawler crane.
And then we would also have required a much longer crane track to complete the bridge immediately in front of the abutment.”
The new development from the Liebherr Plant in Ehingen made it possible to reduce the radius of the suspended ballast to just 13m once the 380t load had been hoisted.
As a result of this small radius, the ballast pallet could be carefully guided past a small row of protected trees during the slewing process.
When the railway bridge was placed on its abutments at a radius of 38m, the hydraulic ballasting device pressed the 440t derrick pallet at a distance of 28.5m.
“Another benefit of using the V-frame for jobs,” said Egger, “is that the derrick ballast pallet has a maximum ground pressure of 150kN per square metre thanks to the integral load distributor plates. The ground pressure from a ballast trailer is at least three times higher and therefore often requires expensive work to prepare the ground.”
Liebherr said the VarioTray detachable ballast system ensured that the job on the bridge site in Moudon was completed quickly. The facility to simply unbolt the central section of the suspended ballast means that there is no need for a mobile crane to stack and destack the ballast slabs.
“Because of the situation on the site, we would have needed a large crane for this job; we would have lost an enormous amount of time and required a great deal of space,” said Egger. “In most cases, our LR 11000 can position the derrick ballast pallet, or at least the outer section, itself since the central section of the ballast remains on the crane and therefore only around 300 to 350 tonnes have to be moved.”
Just a few weeks later, the V-frame was used for hoisting a ship onto the banks of the River Rhine in Basel on the same crawler crane. The adjustable ballast system was used for this job because there were buildings and obstacles in the way of the derrick ballast during the slewing process.