At a steel yard in Ludwigsburg, Germany, crane rental company Wiesbauer lifted a 58-tonne, 45-meter-long gantry crane using two all-terrain cranes. The Terex AC 700 and Demag AC500-8 ATs operated in tandem to move the load to the assembly location.
The project proved to be a challenge. The unwieldy gantry crane had to be unloaded from the delivery truck, after which its girder needed to be moved to the desired position with a tandem lift. Once there, it had to be kept suspended in the air so the gantry crane’s final assembly could be carried out. This was due to the fact that setting the gantry down was impossible due to the goods being stored at the yard. “The distances that had to be spanned and the associated radii, together with the load’s weight, were what made us decide to use our AC 700 and AC 500-8 for this project,” said Marco Wilhelm, project manager.
Before the actual lift, the two cranes had to be set up at the site, but that could not be done during a time that would interfere with operations. This not only had to be done while operations were still ongoing, but also in such a way as to not interfere with them. Of course, this requirement would also apply when disassembling the cranes after successfully completing the lift. To make things even more challenging, operations continued six days per week, and the Wiesbauer team could not count on the work to slow down. “This requirement was also a big part of why we chose these two cranes, as their ease of assembly is outstanding, and they can be set up and disassembled very quickly,” Wilhelm said.
Setting up for the tandem lift
Due to the tight space conditions, there was only one single spot at the premises where the two cranes could be positioned next to each other for the tandem lift. For one of the cranes, this meant being at a significant distance from the assembly position for the gantry crane. “This meant that we had to perform the lift working with high radii,” Wilhelm said.
The Wiesbauer team planned for the AC 700 to deal with the toughest part, as it would have to span the entire width of the yard, all the way to the rear gantry crane rail axis, with its load side. The maximum radius required for this was 42 meters, while the maximum radius required for the AC 500-8 crane was 24 meters. The fact that the AC 700-9 was able to handle this radius made it possible to avoid using additional time-consuming and expensive equipment.
Holding the position
In order to ensure that they would be able to lift the gantry, the two cranes were configured with a main boom and 140 tonnes of counterweight. Once set up, they were ready to lift the load to a height of 15 meters and swing it into position.
An additional telescopic crane was used to fully assemble the gantry crane while the latter’s girder remained suspended in the air. This meant that the Terex Demag duo had to keep the load perfectly in place for several hours.
The Wiesbauer team noted that the cranes and their booms offered outstanding stability, which enabled it to assemble the gantry crane in two working days as scheduled and complete the project to the customer’s full satisfaction.