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Smooth opening and closing

control cable for narrowest bend radius ensures operational safety in low-floor trains
Public transport must be safe under all circumstances. There must be no disruption to operational processes. The doors are often the centre of attention. In this example, a cable used in a moving energy supply system ensures smooth opening and closing. Improved conductors and sheath materials ensure that there are no more failures despite high continuous loads.

Focus on technology and efficiency

The collaboration with igus® began a good two years ago. As a first step, the cable chainflex® CF98, which was specially developed for such applications, was inserted into the existing igus® energy supply system in electric swinging and sliding doors of the low-floor railway as part of due maintenance work. This cable family is designed for very fast applications with a very high number of cycles with a small bend radius and limited installation space. After more than two years of daily practical testing, this has confirmed what has been standard in other transport companies in Germany for years. The cable functions absolutely smoothly, ensuring the doors close and open reliably. "It has defied all adverse conditions and has not failed in heat, cold, snow or ice!" says Hans Bennerscheid succinctly

Low-floor railway

Passenger safety has the highest priority. The doors open immediately if there is an obstacle in the way.

control cable for narrow bend radius of only 4xd

The control cable is primarily responsible for the monitored opening and closing of the doors. It is a safety-relevant part that requires a great deal of attention during all inspections. "To keep our costs as low as possible, we endeavour to only replace wear-resistant parts with high-quality components that meet the latest state of the art," explains Ernst Baerhausen. "And the longer the service life of the cable, for example, the longer the maintenance intervals and therefore our economic costs are reduced," adds Hans Bennerscheid.
"The main difference to comparable cables lies in the conductor," explains Rainer Rössel, Head of Development and Marketing for chainflex® and readychain® at igus®, in conversation. "Copper ages and becomes brittle over time. The CF98 cable is no longer pure copper, but a special alloy that is designed for considerably higher mechanical stress."

Many years of testing have shown no wear on the conductors, even with radii of <3xd and over 60 million strokes. "For over two and a half years, we carried out extensive material research in our laboratory in Cologne in order to be able to offer a suitable cable for users of very small energy chains and the tight bend radius and high stroke rates usually associated with them," reports Rainer Rössel. "And at the end of the trade show was the classic problem solution. With minimal installation space and a tight bend radius, in this case 18 mm, we can provide a functionally reliable cable series with the CF98/CF99."

It has only a slightly lower conductivity compared to pure copper, which was compensated for with a slightly increased cross section - approximately 10 % larger outer diameter compared to a comparable type. However, in view of the considerable increase in requirements in recent years, it is certain that such high-quality solutions will be needed more and more frequently in order to guarantee operational reliability in the critical area of the very small cross section. It makes new applications in energy supply systems possible - for example in the automation sector, in the packaging industry, in the assembly and semiconductor industry as well as in the automotive and banking sectors.

Cable for all cases
"Although we come from the mechanical and plant engineering sector, our cables can demonstrate their strengths in many safety-relevant parts such as automatic doors in buses and trains," explains Rainer Rössel. "In the public transport sector in particular, for example, we have been able to realise solutions to problems with very high train loads in some cases, which ultimately led to greater passenger safety, higher operational readiness and therefore greater cost-effectiveness." Many railway doors have already been equipped with our cables to ensure significantly higher functional reliability. As there is no minimum quantity purchase or surcharge, follow-up costs are also reduced. Over 750 cable types can be supplied from stock worldwide.

Of the 24 low-floor trams, 21 are permanently in operation in Bonn. "We can't afford any downtime," says Alexander Wingen, summarising the requirements. "The technical and therefore also economic advantages of the CF98/CF99 cable convinced us right from the start." And his colleague Oliver Walbröhl adds: "We have joined forces with cities including Dresden, Erfurt, Mülheim and Brandenburg. Not only is the same vehicle series used here, but spare parts are also ordered jointly. At the regular meetings, the focus is not only on operating costs, but there is also a lively exchange of experiences. We are happy to pass on our experience with the control cable for reliable doors."

From left to right: Oliver Walbröhl, Alexander Wingen, Hans Bennerscheid, ErnstBaerhausen, Rainer Rössel

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  • energy chain application examples from practice

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