Stahlbau Schauenberg is primarily active in the fields of plant construction and industrial and commercial construction. In the meantime, Stahlbau Schauenberg has developed into an international group of companies with around 500 employees worldwide and six locations, three of which are in Germany alone.

"Our headquarters are in Kirchzarten near Freiburg. This is where the plant construction is located for process and refinery furnaces, chemical and petrochemical plants and power stations, among other things. At the plant in Ihringen, around 30 kilometers away, around 40 employees carry out the accompanying steel construction, for example reinforcement steel construction, pipe bridges or hall construction. We also have an assembly facility in Leipzig," explains Werner Broß, production manager at Stahlbau Schauenberg for the plants in Kirchzarten and Ihringen.

More power for increased capacities

Crane systems and hoists from Stahl CraneSystems have been used to handle the steel in Kirchzarten since 2009. In the meantime, five projects have been realized in Kirchzarten and Ihringen together with Innokran, the long-standing certified partner of Stahl CraneSystems. The most recent project is the modernization of a crane system in Ihringen. Up to 5,000 tons of steel are processed there every year, with the steel profiles being stored outside. In order to create more capacity, the outdoor warehouse was expanded by a third in 2019.

Werner Broß comments: "Against this background, the old crane with a span of 12.5 meters and a load capacity of six tons was no longer able to cope with the new requirements on the larger site. We therefore had to rethink the logistical concept and ultimately decided to modernize it with a semi-gantry crane."

Larger span and higher load capacity

The new crane with a span of 19 meters was to enable efficient material transport across the entire outdoor area and, with a load capacity of ten tons, be able to perform even the heaviest work. As with a similar project in Kirchzarten, Stahlbau Schauenberg opted for a hoist with an SH 50 wire rope hoist from Stahl CraneSystems in a compact design with low approach and headroom dimensions for this semi-gantry crane.

"As specialists in steel construction, we took on the corresponding adjustments to the crane runways. To do this, we only had to replace the crane runway girders on the elevated crane runway on the hall side and extend the entire crane runway by 24 meters. The elevated crane runway, on the other hand, was completely removed and a new, longer crane runway was erected on new foundations on the ground," says Werner Broß.

Constructive measures preserve the crane runway

Basically, the crane runway on the hall side for the planned larger crane was not designed to absorb the horizontally acting guiding forces during acceleration and braking. "For this reason, we attached horizontal guide rollers to the lower ground-side crane runway of the portal supports to relieve the upper crane runway in order to transfer the guiding forces. The entire crane structure, including the crane bridge, was specially designed to be particularly rigid for this purpose. Other special features of the crane are the additional travel drives, the wind protection and the standstill heaters," reports Christoph Fischer, Managing Director and crane expert at Innokran.

Reliable and safe even in strong winds

Outdoor cranes in particular always have a large surface area exposed to wind and sometimes have to withstand heavy wind loads. This is all the more true when heavy loads are suspended from the hook. The entire statics of the new semi-gantry crane at Stahlbau Schauenberg have therefore been designed accordingly. In addition, the crane has four instead of two travel drives so that it can be operated safely even at wind force 7, i.e. wind speeds of up to 15 meters per second. And even when the crane system is not in operation, it must be protected against strong winds and even storms despite the travel drive brakes being closed. For this reason, there is a wind safety device with electrically adjustable safety bolts between the travel drives.

In addition to strong winds, cranes for outdoor use are always exposed to various weather conditions. This means that there is always the problem of corrosion and the formation of condensation, particularly in the switchgear and motors due to changing temperatures. For this reason, the control cabinet attached to the side of the crane bridge is made of stainless steel. The upper belt trolley is protected from precipitation by a special roof construction. All switchgear, motors and hoists as well as trolley and crane travel units are also equipped with standstill heaters.

Time savings during loading and unloading

The new semi-gantry crane at the Ihringen site has changed many things. This not only includes the fact that the expanded storage capacities can be optimally utilized thanks to the larger crane. According to Werner Broß, there are other advantages, above all the immense time savings and greater flexibility in material transportation. The maximum speeds of the hoist (8 meters per minute), trolley (20 meters per minute) and crane trolley (40 meters per minute) contribute to this.

Thanks to the expansion of the external warehouse, trucks no longer have to maneuver laboriously to access the site, as was previously the case. This saves time, and with the new crane, also during loading and unloading, as Werner Broß emphasizes. "We are no longer forced to turn the material 90 degrees for transport and maneuver past the hall-side supports, but can use almost the entire span of the crane to move the steel profiles with an average length of 16 meters in parallel."

The article appeared in materialfluss 11-12/21.