Schaeffler Bearing Package Keeps German Locos Rolling

Schaeffler Bearing Package Keeps German Locos Rolling FAG wheelset bearings are helping to reduce maintenance, improve safety and cut handling costs for locomotive manufacturers and the DT3, Germany's most advanced driverless subway system. In a similar way to automotive OEMs, train and locomotive manufacturers are beginning to see the value of sourcing complete subassemblies from one supplier, rather than purchasing multiple, individual components from different suppliers and then doing the assembly work themselves. For example, take wheelset bearings. Rather than buying individual bearings and housings from different suppliers, wheelset bearing elements for an entire bogie, for example, can be sourced as a complete solution from one supplier. Not only does this result in improved logistics and handling, but also cuts costs for the customer. Only one ordering code is required and the customer receives the assembly, including the eight individual components needed for a complete bogie. Furthermore, the risk of mixing up the parts is minimised, reducing the risk and improving safety. Locomotive manufacturer Bombardier, for example, now partners with bearings manufacturer Schaeffler on its Class 185 dual frequency locomotive, designated Traxx F140 AC, which has a very successful track record with Germany's railway operator, Deutsche Bahn. The Class 145 derivative is currently the most common locomotive in the marketplace. The Schaeffler Group's Railway Division, with its INA and FAG brands, has been involved from the development stage as an engineering partner - initially as a supplier of transmission bearings and later also as a supplier of traction motor bearings. In fact, the Schaeffler Group is now the sole supplier of FAG cylindrical roller bearings, deep groove ball bearings and four-point bearings, as well as current-insulated cylindrical roller bearings, to the Bombardier site in Henningsdorf, Germany. Since 2004, Bombardier has also purchased FAG wheelset bearings - housings including cylindrical roller bearing units - for the BR 185.2. In doing this, Bombardier's processes are optimised: the wheelset bearing elements for an entire bogie are supplied as a complete kit in a wire crate. Class 185 Traxx locomotives were designed as modular multi-system units incorporating three-phase asynchronous propulsion technology. They are used in fast cross-border freight services and have been preconfigured for Europe's future ETCS/ERMTS train control and safety system. The locomotives run on two-axle Flexifloat bogies and deliver a maximum power output of 5600kW. They have a starting traction effort of 300kN and reach a top speed of 140km/h. The BR 185 is designed to operate on standard gauge 15 or 25kV AC networks. The platform-based locomotive can be further developed into multi-system machines that are capable of operating on 1.5 and 3kV DC systems (Traxx F 140 MS). In addition to Germany, Austria and Switzerland, the locomotive is to be used in France, Luxemburg, Denmark, Sweden, Norway and Hungary. Germany's most advanced subway system was brought into service in Nuremberg earlier this year. The DT3 two-car unit (manufactured by Siemens Transportation Systems and operated by VAG Verkehrs-Aktiengesellschaft Nuremberg) is a new, fully automated, driverless vehicle. The FAG wheelset bearings (rolling bearings and housings) for the DT3 bogie frame were supplied by the Schaeffler Group. According to recent studies by the rail industry, introducing driverless, automated operation will increase safety and reliability, offer lower energy consumption, more flexibility and higher economic efficiency. The higher initial investment costs for automated operation are counter-balanced by lower energy consumption and higher safety thanks to various measures, including the continuous exchange of data between track and vehicle, and more flexible and demand-oriented deployment options of the rolling stock. Passenger benefits come mainly in the form of significantly reduced cycle times. While conventional vehicles achieve a maximum of 200-second cycle times, automated operation would enable 100-second cycles. The wheelset bearings on the DT3 are FAG 808246 double-row cylindrical roller bearings with 120mm bore diameter, 200mm outside diameter and a width of 130mm. The bearings are prelubricated for one service interval and require no maintenance for six years or 1.2 million kilometres. A special surface coating of the inner ring bore helps avoid damage to the axle journal during bearing mounting and dismounting. Specialists at Schaeffler's Railway Bearings division pulled out all the stops when it came to the development, design and choice of materials for the wheelset bearing housing. For maintenance purposes, a split housing was required. This offered the advantage that only the bottom part had to be dismounted during maintenance, while the top of the housing stayed on the bogie. This meant the axle could easily be taken out of the bogie. But the housing also had to resist the extreme loads that occur as a result of the design of the primary suspension, a steel suspension with a rubber guiding element. Additional demands for weight reduction and high security standards also had to be met. The optimum solution that met all these requirements was achieved only by using a combination of FEM calculations and 3D modelling. The FEM calculation results were verified during test rig trials. FAG design engineers decided to use heat-treated, hardened spheroidal graphite cast iron, which offered the advantage of high strength combined with good ductility. It is the only material that met the compact, lightweight design requirements for the housing. At this year's InnoTran' trade fair in Berlin (19th to 22nd September 2006) the Schaeffler Group will showcase its range of innovative bearings, system solutions and comprehensive services for bearing supports in train wheelsets, bogies, transmissions and traction motors, as well as yoke-type track rollers for active tilt technology. 'All these bearing solutions are outstanding for long life and low maintenance requirements', commented Dr Raimund Abele, head of the Railway Product Line at Schaeffler Group Industrial. 'As a leading, full-range supplier, we can offer our customers all solutions from one source'. Also on show at InnoTrans is Schaeffler's new insert bearing for low-floor trams, operated for example, by public transport company Hallesche Verkehrs. These FAG insert bearing units are tapered roller bearing sets, which are manufactured to such high precision that the required preload is achieved after installation into the wheel unit. Furthermore, they are easier to mount and maintain, require less installation space and offer longer life.