Axlebox Bearings for High-Speed Trains
Schaeffler Group Industrial (INA/FAG) is the development partner for the axlebox bearings incorporated in the Velaro high-speed trains destined for Russia and China. Its Business Unit Rail has developed one complete axlebox bearing with swing-arm housing each for the two bogie variants. The axlebox bearings consist of an upper and lower housing part as well as the rolling bearing; the bearing for the Velaro Russia has an additional housing ring. The trains are scheduled to serve the Beijing-Tianjin route in China as from 2008 and will connect the Russian cities of Moscow and St. Petersburg from 2009.

TAROL units for high loads
Double-row TAROL tapered roller bearing units are the core components of the heavy-duty axlebox bearing units. Two different bearing sizes are used due to the different axle loads. In particular, the components for the Velaro Russia must be able to withstand extreme operating and environmental conditions. The TAROL bearings are designed for loads of up to 18.5 tons and the axlebox bearing housings can be used within an extremely wide temperature range. TAROL bearings for the Velaro Russia have a bore diameter of 150 mm and are equipped with reinforced polyamide cages. To ensure correct installation of the bearings, Siemens fitters receive expert training by specialists from FAG Industrial Services (F’IS), the Schaeffler Group’s service subsidiary. Thus the Siemens staff is certified by the Schaeffler Group and is therefore authorized to mount these axlebox bearings.

The ready-to-fit TAROL units are especially easy to install and are based on double-row tapered roller bearing units. During manufacture they are sealed and greased and their clearance is adjusted. Schaeffler Group Industrial can provide the bearing units in metric and imperial dimensions, along with all the necessary components and bolts for quick and safe mounting. Customer-specific individual parts, spare parts and housing adapters are available upon request.

Housing structure for extreme temperatures
The housing of the axlebox bearing for the Velaro Russia has been designed to resist extreme temperatures and offers a minimum impact strength of 12 joules at -50 degrees Celsius – a value that is normally reached at -25 degrees Celsius. It is made of spheroidal graphite cast iron according to DIN EN 1563. The strength of the housing structure has been optimized and confirmed using FEM (finite element method) calculations. FEM describes not only complex geometries, but also the complex progression of the force flow in the housing in a realistic manner.

The housing as a connecting element between the bogie and the wheelset has the task of transmitting forces reliably. Its design depends on how the forces are introduced into the housing. The optimized shape improves the pressure distribution inside the rolling bearing so that the specific load is reduced and peak loads are prevented.

Distributed traction system concept for high-speed traffic
The trains for Russia and China are based on Siemens’ Velaro platform, which is a further development of the high-speed ICE 3 multiple unit concept operated by Deutsche Bahn. In a multiple unit train, the traction equipment and all technical modules are all arranged under floor and distributed over the entire length of the train. This contrasts with the push-and-pull approach where everything is packed into two locomotives coupled at the front and the rear of the train formation. For the same length of train, therefore, this means an increase in seating capacity of around 20 percent as the absence of locomotives creates more space for passenger accommodation. The Velaro for China, for example, has room for over 600 passengers. Because 50 percent of the axles are driven directly, the train can accelerate more effectively. Moreover, this traction concept enables the train to run on track sections with steeper gradients of up to 4 percent. One additional but equally important advantage is the lighter load on each axle due to the improved distribution of weight over the vehicle as a whole.

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