And the wheels go round and round, round and round
22.06.2015 - Oliver Hagenlocher
Be truthful, do you know how old your summer tires on your car are? How many miles you've already travelled with them or what the service life of an average tire is? Well, we can at least answer the last question: it is between roughly 25,000 and 50,000 miles and entirely dependent on what kind of car you drive and what kind of tires you need. The general rule is the larger and wider the tires, the lower the service life because these types of tires generally require softer rubber mixtures. In light of this, the service life of another type of wheel seems even more impressive than it already is.
With or without tires? The railway wheel
Just like car tires, railway wheels, too, are the result of a long chain of technical developments – far longer if you remember that the first commercially successful locomotive, the “Adler”, was constructed as early as 1835, almost 70 years before the first “tire with tread for cars” made by Continental was marketed. Even though the first railway wheels were designed like coach wheels (spoked), the solid wheel, consisting of wheel disk and wheel tire, gradually gained acceptance. This afforded the advantage that only the wheel tire, and not the wheel disk, needed to be replaced if the wheels were worn. This is similar to the principle of car tires where, after all, only the tire needs to be replaced and not the entire wheel.
Solid wheel offers durability
Such a railway wheel, consisting of two parts, has a service life of around 370,000 miles, already a considerable figure when compared with a car tire. As more and more high-speed trains come into service, and as wheels are subjected to continually increased stress accordingly, it was necessary to find a new solution which was ultimately found with the solid wheel, what is called the monoblock wheel. These solid cast-steel wheels, as the name suggests, are manufactured completely in one casting. This not only makes the wheel far lighter, but also greatly prolongs the service life to 620,000 – 1,550,000 miles.
Fully manufactured railway wheels
Automated manufacturing of large quantities of railway wheels cannot be done with standard machines. EMAG has the VLC series for this and its machining areas can be configured virtually at will for any requirement. Two machines in particular, VLC 800 and VLC 1200, are designed for machining large, heavy components. The machines feature a pick-up automation system where the working spindle is loaded automatically from an integrated parts storage facility and then transports the workpiece into the machining area. It has been equipped with turning and drilling tools for machining railway wheels (see a video clip of the machining process here).
With 20 to 30 times the service life of a car tire, modern railway wheels are real high-performance products – above all if we consider the high strains and stresses such a wheel has to endure over its lifetime. The same applies to EMAG’s VLC series, which is designed for long-term and high-quality production of workpieces up to 1,200 mm in diameter. EMAG: always on the right track.