Manitowoc Crane Group

Three all-terrain cranes from Manitowoc’s Grove brand were used in an unusual and space-restricted roof lift in Germany. Gräser Autokrane, a subsidiary of rental company and lift specialist Eschbach, was selected for the job to position a 160 t roof structure at a gas station in a confined residential area in Mannheim.

Thomas Meier, project manager at Gräser Autokrane, said the available space and the structure of the roof both presented major challenges.

“Prior to the lift we were called to a meeting to discuss the challenges of the job,” he said. “Normally these lifts are everyday jobs but the dimensions of the roof were unlike any other gas station. Plus, with the confined space we needed precise positioning and movement. Our 300 t crane could handle the lift alone but to prevent tilting, and for added lift safety, we sent another two all-terrain cranes to the job.”

Gräser Autokrane used its 300 t GMK6300 as the main lift crane with support from a 220 t GMK6220-L and a 130 t GMK5130-1. With the cranes selected, the company moved to on-site positioning and used Manitowoc’s Compu-Crane lift planning software to draw up the best schematic.

Using this software made the lift planning much easier, said Thomas Meier. “We chose Grove cranes for this project as we knew we could take advantage of Manitowoc’s Compu-Crane lift planning software,” he said. “We knew how confined the space was, so positioning was paramount. But the software enabled us to position all three cranes precisely and to simulate the lift before actually doing it on site.” The space between the 8 m tall columns for the roof and the rear wall of the property was just 6 m. However with some slight adjustment of one of the column positions, Gräser Autokrane was able to fit the GMK6300 into this critical position. Once in place there was just 10 cm between the GMK6300 and the rear wall.

With all three cranes in position, the lift began. The structure consisted of a 45 m long central section with two semi circles either side, each with a 40 m radius. The lift took just two hours and was monitored throughout by support crews in man baskets using spirit levels. Gräser Autokrane was founded in 1938 by Willy Gräser in Mannheim, Germany. In 1987, the company was sold to Manfred and Anneliese Eschbach. Together with Eschbach GmbH, the Eschbach Group has a total of 40 mobile cranes with capacities of 30 – 300 t. The company operates in Germany, particularly between the regions of Frankfurt and Karlsruhe.