Increasing demand for long hollow-core concrete slabs meant that Prefaco at Houthalen-Helchteren, Belgium, had to modernize its portal crane infrastructure. They invested wisely, renovating two old portal cranes and equipping them with tandem control to allow slabs of up to 18 metres to be manipulated.
Using vintage cranes to handle 18-metre slabs
Business has been on the up in recent years at construction material producer Prefaco after several years of reduced economic activity. Formerly under the Echo banner, their plant in Houthalen-Helchteren produces hollow-core prestressed concrete slabs, always on demand and mainly for use in industrial buildings and warehouses.
“The business was at a low ebb during the crisis years when demand was low and competition fierce,” says the plant’s Technical Team Leader Ben Gysen. “But now we have very busy schedules again, producing 24/7 in a constant rush to deliver on what we promise.”
Longer slabs bring logistical challenges
Business has also changed a bit compared to the pre-crisis years. “There is an increasing demand for longer hollow-core slabs,” explains Gysen. “Back in 2010 we rarely needed to produce slabs of 12 metres or more, but for a few years now we’ve quite often been getting orders for long slabs up to 18 metres with thicknesses up to 40 centimetres.”
This evolution has brought about some logistical challenges. “In fact, we weren’t really equipped for handling these very long slabs. Previously, when we had to deal with such giants, we transported them using our two old portal cranes, but it was rather cumbersome, needing two operators and some special safety arrangements. Good for now and then, but not for every day.”
For a few years we’ve quite often been getting orders for long slabs up to 18 metres with thicknesses up to 40 centimetres
Operating two cranes as one
So Prefaco looked for specialist advice. “We didn’t want to purchase a new crane - that would have been too big an investment,” says Gysen. “But our existing cranes were more than 25 Years old and we were not sure they could be further used in an effective manner. But TCS confirmed that after installing new control cabinets and remote controls they would serve very well. They also suggested implementing tandem control, which means you can link both cranes and operate them as if they were one machine. A great idea. We let them install it and we’ve been happy with it ever since.”
Controlling the cranes in tandem can be initiated and carried out by one remote operator. The operator travels the cranes to a certain distance, for example 10 metres, and then activates tandem control, setting one crane in slave mode. From that point, both cranes and their hoists can be controlled simultaneously from the master crane. While in tandem mode, a number of safety signals are being exchanged, including the overload indicator and the end switches for hoist lifting and descending and crane and trolley travelling. This ensures that the tandem system appropriately reacts whenever one the two cranes sends a safety signal.