Tandem hoist on cellar ceiling: Haslach installs giant prestressed concrete trusses

Heads were spinning during the planning: the objective was to install ten prestressed concrete trusses, each weighing 98 tonnes, for the roof in a hall that had a cellar running underneath. The hall floor's support load was limited, and space was also very restricted. Getzner's deliveries also had to continue uninterrupted. Tobias Haslach, owner of Kranverleih Haslach GmbH, recalls: “After extensive planning and many detailed calculations, we were able to come up with a solution for the installation work in conjunction with the other companies involved. We stabilised the cellar ceiling from underneath with ceiling supports in order to achieve the support strength required to allow our LTM 1300-6.3 to work on this cellar ceiling.” Alongside the 6-axle mobile crane, the special transport also drove onto the cellar ceiling to unload the 98-tonne concrete truss.

Haslach used an LTM 1230-5.1 as the second crane for the tandem hoist. Tobias Haslach recounts the challenges: “We set up the 5-axle vehicle on a specially filled embankment outside the hall. Due to the positioning behind a concrete wall, we were only able to coordinate with the work team via radiotelephony. The truss also had to be guided around the LTM 1300-6.3.” When lifting the truss from the truck, both mobile cranes were working at maximum capacity with a load of 51 tonnes each and a radius of 13 metres and 15 metres respectively. Two reinforced concrete trusses were installed in one day. With a length of 47.3 metres and a total weight of 148 tonnes, the transport required a special permit and was only allowed to travel at night. After each installation, both mobile cranes were moved with all their equipment including ballast and positioned for the lifting of the subsequent reinforced concrete trusses.

“The cooperation on the construction site was excellent. Operations at the Getzner textile factory continued virtually undisturbed. Our two crane operators were also delighted with the collaboration of everyone involved on site,” says Tobias Haslach. The family-run company Kranverleih Haslach is based in Wertach in southern Germany and relies entirely on Liebherr for its nine mobile cranes.