Riga Mainz achieves complex asymmetrical lift with Liebherr LTM 1650-8.1
Crane and heavy haulage contractor Riga Mainz deployed a Liebherr LTM 1650-8.1 to position a 70 tonne pontoon in a flooded gravel pit.
The pontoon, measuring over 20 metres in length, was positioned on the flooded pit as part of the process of expanding a gravel plant in Babenhausen in the German state of Hesse.
Crane operator Werner Gebel set up his 8-axle machine parallel to the load, with the lake at its rear. “The crane naturally delivers very high lifting capacity values at the rear. That is particularly the case if I extend the outriggers fully using the Liebherr VarioBase® program,” explained Gebel. In this mode, the LICCON crane control system calculates the maximum lifting capacity for every boom position. The maximum values are achieved when the crane is operated over its rear outriggers.
In this particular lifting project, the challenge for the crane was to position the gross load of around 70 tonnes into the water at a radius of 25 metres. To achieve the hoist, the LTM 1650-8.1 was set up with its full slewing platform ballast of 155 tonnes. To enable the pontoon to be hoisted fully over the surface of the water, the hydraulically adjustable ballast radius was increased from 7.4 metres when it picked up the load, to the maximum distance of 8.4 metres.
Uwe Langer, Riga Mainz managing director, planned the complex crane job in minute detail. He explained: “To attach the large load, we had to work with rope pulleys and fastening equipment of different lengths due to the fact that the centre of gravity was far from central,”
“First of all, however, we had to calculate the load case for the hoists using the material thicknesses of the floating section as there were no precise data available about the weight of the pontoon. That then enabled us to develop our hoisting concept. In addition, as a result of how close the crane set-up area was to the edge of the embankment, we had to carry out geological studies of the subsoil. We had to ensure that the ground pressure under the load distribution mats would not cause the soil to collapse.”