Nothing stands still in the transport sector, and that is especially true for railway vehicle design. Noise cancelling seats, a budget zone for short journeys, seats that can be rearranged to allow for peak and off-peak times, innovative air purification systems, and much more. Several years ago, German National Railways developed its so-called ‘Ideas Train’ – a train mock up demonstrating design optimisation. It is a highly visible example of how rail vehicles are being continuously innovated.
But not all the innovation is as visible as this. Take the case of cable management in rail vehicles. These days, your average high-speed train has about 200 km of cables and wiring. That’s about as much cable as in an Airbus A380 jet-engine plane. As a passenger, you don’t see any of this wiring, but you do experience its benefits, whether it’s a screen on a seat showing the latest blockbuster film or a fail-safe braking system. And the amount of cable is increasing dramatically. The real challenge is how to install cables quickly and easily, and hold it securely in place at the lowest cost possible.
Paul Cocheril, EMEA Railway Market Manager at HellermannTyton, deals with such challenges in trains on a daily basis: “Whereas cables and wires in earlier rail vehicles were mainly to distribute electrical power through the vehicles, today we see data and signal sent back and forth between cars and the locomotive – for passenger comfort but also for more intelligent and more efficient operation of the train. At some point you face the question of how to route all this cable once it leaves the ducts and trays in the floor or ceiling – for example, around the doors.”
The traditional method is to use metal butts riveted into place. “This is very labour intensive”, he explains. “The butts first have to be installed. And often that made it more difficult to maximise the efficiencies of pre-confection. Metal butts are also relatively heavy, so they add a lot of extra weight to the rail vehicle, without any particular additional structural benefit.”
“The real challenge is how to install cables quickly and easily, and hold it securely in place at the lowest cost possible.”
“Early adopters in the industry”, he reports, “are moving away from this approach and are using EdgeClips instead, which are a more efficient solution. These use existing edges to anchor a cable harness firmly and securely, even where strong vibration is a constant factor.
EdgeClips – A hidden champion
HellermannTyton began developing its EdgeClip range in the mid-1990s primarily for the automotive industry, where considerations of weight and space are of utmost importance. These “hidden champions” can guide cables and wires in any routing direction. EdgeClips can be pushed into place easily by hand, which saves time in comparison to riveting metal butts in rail vehicles with tools. And they are ideal for narrow spaces and applications where drilling holes or using adhesives is not practical. One enormous advantage is that they can be easily pre-assembled on the harness, which saves train manufacturers a lot of time during construction.
Next generation – Running two cables parallel along the edge
“The EdgeClip was developed as a custom product to meet a specific challenge, but like a lot of our products, it was so successful that it has become a standard product,” says Paul Cocheril. “In the meantime, it’s used in many different industrial applications, including in railway vehicles.”
“EdgeClips can be pushed into place easily by hand, which saves time in comparison to riveting metal butts in rail vehicles with tools”
A more recent development of the EdgeClip is a version that routes two harnesses or cables in parallel, one on each side of a surface edge. Inside HellermannTyton, some refer to it light-heartedly as the “Minnie Mouse” EdgeClip, in reference to the Disney character, because it’s tiny and looks like it has prominent “ears”.
“The advantages of parallel routing are very clear,” says Paul Cocheril. “Depending on the weight of a harness, let’s say that the harness or cable has to be fastened approximately every 30 cm horizontally, or every 50 cm vertically. We’re talking about a significant reduction in process costs and time – potentially up to two-thirds – compared with the butt and tie method, to secure the same amount of harness or cable in parallel in a carriage.”
The metal claws at the heart of the EdgeClip withstand vibration and support the weight. Pre-confected with the harness, all it takes is one simple process step – without the need for any tools – to secure parallel cable runs. “If you take into account the cost of metal butts and the time spent installing them, the EdgeClip is a highly efficient and economical option. Savings are significant, and that can take some of the pressure off overall costs.”
Savings are not just in initial manufacture of the railway vehicle. According to one leading international provider of rail technology, the average lifespan of a train is 40 years. As a rule, however, rail vehicles are modified and refurbished at least once during their lifetime, and that includes cable assemblies. These are refurbished about every 20 years.
“If you take into account the cost of metal butts and the time spent installing them, the EdgeClip is a highly efficient and economical option.”
“What you save on cable assemblies and installation on your average train in 2022 will be repeated – in part at least – later, when the assemblies get their overhaul,” Paul Cocheril adds. “This makes using EdgeClips – and especially one capable of routing harnesses in parallel – even more attractive. Just imagine the huge increase in long-term cost and time spent on installation when metal butts are used!”
Material characteristics of the EdgeClip and ties make these highly suitable for use in the railway sector. The cable tie is made from heat stabilised polyamide 6.6 (PA66HS), the foot from UV-resistant polyamide 6.6 (PA66W), and the EdgeClip clamp from double tempered and coated steel. It meets the EU RoHS directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, and it meets DIN EN 45545-2 European norm for fire protection on railway vehicles and hazard level HL2 in requirement set R22, R23.
“EdgeClips have long been an unsung hero in many industrial applications, and they’re also now on the way to being the product of choice for many applications in railway vehicles,” says Paul Cocheril. “And of course the advantages are multiplied when the same fixing point can be used to route parallel cables, like with our “Minnie Mouse”. EdgeClips may be hidden behind cladding in railway vehicles, but their cost-saving potential is very visible on the bottom line.”
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