Even if the realization is not entirely new, the recent crises act as a booster: the future of mobility must imperatively become safer, more efficient and, above all, more sustainable. For this reason, among others, numerous institutions and companies are investing in research projects for the constructive optimization and new development of components and digital systems. The focus is on optimized recycling management and resource-conserving operation of vehicles, both in high-speed and in freight and local transport. The renowned automotive and industrial supplier Schaeffler from Herzogenaurach in Franconia is focusing not only on the new development of components, but also on digital solutions.

Balls instead of rollers: revolutionary TwinTandem wheelset bearing

As proven specialists for high-quality rolling bearing solutions, the experts at Schaeffler are currently developing a new type of wheelset bearing concept and, in this context, are announcing an innovative leap in rail transport. The R&D project, which goes by the name of TwinTandem, is intended to open up performance potential that will have a significantly positive impact on operation and maintenance. The central innovation of the TwinTandem inner bearing is the use of ball bearings with significantly reduced friction. They enable a low temperature level even at high speeds, which in turn leads to a sustained extension of the service life of the greases used and thus of the entire wheelset bearing.

"The TwinTandem is currently one of our most promising development projects," explains Dr. Michael Holzapfel, Senior Vice President Business Unit Rail - Industrial Europe at Schaeffler. "With the use of ball bearings, we are enabling a significant improvement in rail traffic in terms of running performance and maintenance intervals. According to our calculations, validations and tests, we are talking about an expected service life of up to three million kilometers - a real innovation, especially for high-speed traffic."

Let numbers speak

These forecasts are backed up with thoroughly impressive figures. For example, extensive studies using Schaeffler's Bearinx calculation tool revealed, among other things, a weight reduction of the TwinTandem of up to 20 percent compared to a classic tapered roller bearing. The geometry-related friction reduction is said to be as high as 55 percent. Compared with inner bearings with rollers, this results in a predicted CO2 reduction of more than 1.1 metric tons per million kilometers driven and bearing at typical load. And this figure is also impressive: The use of the TwinTandem with internally mounted wheelsets enables a bogie weight reduction of up to 30 percent, thus reducing resource consumption and easing the burden on the rail network.

The fact that there is substance behind all these figures is proven by the Best Paper Award at the World Congress of Railway Research in Birmingham in June 2022.

And there's more

But what has been achieved does not seem to be enough for the experts at Schaeffler. They are currently already working on measures to further optimize the TwinTandem in terms of efficiency and sustainability. The central element of these efforts is the material used. In order to further minimize friction and maximize the service life of the greases, they are considering using high-quality ceramics to manufacture the rolling bearings. Under the aspects of climate protection and sustainability goals, the use of green steel is also to play an important role in the future. And to take account of the ubiquitous topic of digitization - keyword: future-proof rail transport - bearing identification is to be carried out by means of Data Matrix Code (DMC).

Thanks to DMC: stationary measurement data for the diagnosis of bearings.

In conjunction with the internationally recognized and manufacturer-independent interface standard GS1 EPCIS, the DMC is intended to enable data exchange between component manufacturers, OEMs and rail operators. Among other things, the DMC can be used to assign vehicle-specific data from stationary sensors to the bearings installed in the train and use it for their digital condition diagnosis. This is not an entirely new topic for Schaeffler, as it has already successfully tested precisely this procedure as part of a pilot project with Stadler Rail AG as the manufacturer and a Swiss rail operator. The central point of contact for the mutual provision of production, operating and maintenance data for the components is the database of the European EPC Competence Center, the European market leader for solutions and services relating to the Electronic Product Code (EPC). Schaeffler sees the great advantage of this link with the trackside data acquisition system in the fact that meaningful condition monitoring is possible even without retrofitting a separate sensor system in the vehicle.

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