The SF 500 high-speed bogie

The Velaro E from Siemens Transportation Systems is the fastest series-produced train in the world. One of the reasons why the ‘supertrain’ is so successful, is due to the SF 500 high-speed bogie developed and produced in Graz. It sets new standards in terms of flexibility of use, passenger comfort and life-cycle costs.

In the middle of this year, the Velaro E, Spain’s latest high-speed train, will be put into service. The eight-unit trainset, designated the AVE® S103, will complete the 635km long route between Madrid and Barcelona in less than two and a half hours. During the process, operational speeds of 350km/h will be reached. During tests on the Iberian peninsula, vehicles from the same production series have even reached top speeds of over 400km/h. One of the key components for this outstanding performance from the Velaro platform is the SF 500 high-speed running gear.

The running gear was first used for the ICE® 3, the current flagship train of German Rail (DB AG). Since then, there have been orders from The Netherlands State Railways (ICE® 3), the Spanish operator RENFE (Velaro E), the Chinese Ministry of Railways MoR (Velaro CN) and the Russian Railways RZD (Velaro RUS). Once the current orders have been completed, over 2,500 bogies with the SF 500 high-speed technology will be in service. The increase in the number of high-speed routes in all parts of the world is without doubt the basis for this success. In order for a company to assert itself on the global market, however, it must also be able to provide cutting-edge technology, of course. With the SF 500, Siemens can do this in several areas very successfully.

Unparalleled flexibility in service

Safety systems, track quality, specific details of operation, standards and climatic conditions: the requirements of operators such as DB AG, RENFE, the Russian RZD or the Chinese State Railways could not be more different. Nevertheless, all of them have decided in favor of the Velaro and therefore the SF 500 running gear. The key to this adaptability is the underlying modular design of the bogie from the Graz factory, the bogie competence centre of Siemens Transportation Systems.

When the high-speed SF 500 bogie was being developed, strict attention was paid to ensuring that it could be adapted for as wide a range of operations as possible. Whereas the requirements of the German and Netherlands railway companies were very close, considerably higher ambient temperatures had to be taken into account for the version to be supplied for the Spanish Velaro E. In contrast, the exact opposite was demanded by the climatic conditions in Russia, where it is necessary to guarantee that the safety-relevant components will continue to function correctly at temperatures down to -50 °C.

The situation was similar when it came to different trackworks in that there was no difficulty in adapting the SF 500 from the normal gauge versions used in central Europe and China to the 1,520mm broad gauge of Russian Railways.

Especially when it comes to the track, the bogie has another important advantage: The system was developed to meet high stability requirements so that it would even be possible to drive on tracks with an unfavorable contact geometry (l = 0.6) without restrictions.

Another flexibility factor that is essential for worldwide use is that the SF 500 can be equipped with different country-specific train protection antennas, thanks to the bogie’s antenna carrier.

High adaptability to different operational requirements

The Velaro platform has been optimized for the widely differing operational requirements. A significant portion of its wide application range can be attributed to the bogie. This is because the SF 500 bogie, for example, can also be used on tracks of a lower standard and thus entails less demanding requirements when it comes to track maintenance.

Each car rests on two bogies. This enables the individual cars to be coupled and uncoupled quickly and without complex lifting platforms during maintenance work. Similarly, complete bogies can be exchanged quickly and easily – a clear advantage for the availability. Last but not least, the possibility of rapidly coupling two autonomous trains to form a double train during service again underlines the entire system’s operational flexibility which is incorporated in the basic concept.

The 8800 kW of traction power which is distributed over the train has two advantages: the optimum adhesion utilization helps during acceleration and routes with a rising gradient of up to 4‰ can be driven on. Moreover, it also enables traction components to be fitted underfloor. As a result, the whole length of the train and the station platform length are available to the passengers.

Even a larger number of seats such as in the Velaro CN with its 3+2 seating arrangement is no problem for the SF 500 as it tolerates high loads.

Very high speeds and outstanding comfort should not be mutually exclusive

The development department in the Graz factory of Siemens Transportation Systems is now one of the world’s best-known teams when it comes to engineering design know-how, especially in the area of comfort. The close collaboration with the Technical University in Graz and testing in the Siemens test centre in Wegberg-Wildenrath are decisive prerequisites for this. However, the Graz bogie specialists can also use the latest research and development equipment in their own facility. And these investments lead regularly to pioneering results. The same applies to the SF 500, whose levels of comfort are unparalleled. One proof of this is provided by the outstanding results achieved by the Velaro E on the Madrid-Barcelona route.

The integral engineering design principle, which always considers the interplay of track, bogie and car body, is responsible for this. The bogie is based on an optimized axle guide which transfers the traction, braking and track-guidance forces from the axle box to the bogie frame. The bogie frame rests on two primary springs on each wheelset. An additional hydraulic damper is arranged parallel to the springs. The redundantly arranged hunting dampers provide for very smooth running and stability even at high speeds. The secondary suspension is a highly developed air suspension system with large additional volume.

The system has been developed in close cooperation with the engineering team at the Siemens Krefeld plant. Here, the structural dynamic properties of the car body have been harmonized with the suspension systems of the bogie and an optimum design of the coupling elements has been implemented regarding structure-borne noise.

The transversely flexible motor suspension system is really unique. The motor and its support is suspended from a pendulum mechanism and its mass therefore acts as an oscillation compensator. The outstanding dynamic characteristics are based on optimum harmonization of the spring-mass system. This is why the SF 500 high-speed bogie has such an optimally engineered suspension system. In order to fully exploit the potential of the technical design, extensive running calculations and a whole series of practical tests were carried out on the track. The overall result is that, today, excellent passenger comfort, stability and the transmission of structure-borne noise are possible.

Extremely low life-cycle costs

The special technical design features of the SF 500 enables economically efficient operation and, above all, allow a considerable reduction of the bogie maintenance costs. As regards the motorization, low energy costs can be achieved through the recovery of braking energy. Low-maintenance motors and the high proportion of regenerative braking energy ensure high availability and low operating costs.

One of the characteristic advantages of bogies from Graz is also especially noticeable in the case of the SF 500: the low wear on the wheels and the track. Several factors are responsible for this: the small wheel base, which ensures a good striking angle, the high degree of motorization, which considerably improves adhesion utilization, and, finally, the uniform distribution of weight throughout the train. All these advantages, combined with the high wear reserves of the SF 500, have a beneficial impact on the maintenance intervals and re-procurement costs of new wheels. Above all, the transversely flexible motor suspension makes a decisive contribution to this because it substantially improves the influence of the moments of inertia around the vertical axis and enables optimum design of the wheelset link. Moreover, the extra stability achieved as a result makes the bogie considerably less susceptible to unfavorable wear states and therefore the wheels do not have to be reprofiled until later.

Thanks to the outstanding passenger comfort, there is no need for car-body coupling dampers, secondary vertical dampers and the maintenance costs associated with them.

Ease of maintenance as a principle of construction

To facilitate maintenance, special attention was paid to the accessibility of parts which are subject to regular wear and components which have to be visually inspected. Divided axle journal bearings enable rapid replacement of a wheelset. The axle journal bearings do not have to be re-lubricated apart from during scheduled major overhauls.

Moreover, short bogie replacement times are made possible by the low number of mechanical connections between the car body and the bogie. The motors can also be removed from underneath the vehicle.

Given that the powered and trailing SF 500 bogies largely consist of identical components, there are clear cost advantages with regard to the procurement and storage of spare parts.

The easiest way to maximize the availability of the SF 500 over the long term, is to arrange for the Siemens Maintenance Service to carry out the maintenance. A pioneering service that Siemens is able to offer on the basis of its know-how and, above all, its worldwide presence.

Outstanding level of safety

To Mars and back is approximately 100 million kilometers, a running distance over which the high-speed SF 500 has been able to demonstrate its safety in the ICE fleet. In order to achieve this, an enormous effort had to be put into development of the bogie. All the characteristics relevant to safety were designed with the help of the latest engineering tools. During the technical design phase, all conceivable failure scenarios were played out in the framework of an FMECA (failure modes effects and criticallity analysis).

Even in the event of fire, the system continues to provide maximum safety. The train can continue traveling at 80km/h for 15 minutes after breakout of a fire. This is a huge advantage in respect of the evacuation concept.

Extensive tests were carried out. Component tests, vibration tests in the test bay, driving tests in the Siemens test centre in Wegberg-Wildenrath and many series of measurements on the track. Of course, the system was also tested and inspected in great detail during the certification process – at 385km/h in the case of the Velaro E – before being approved.

Optimal harmonization of the suspension and damping systems results in the bogie’s unique insensitivity to impacts caused by failures in the track geometry.

Outstanding safety, unparalleled comfort, high availability, ease of maintenance and, above all, adaptability to the most varied of conditions in worldwide high-speed transportation all make the high-speed SF 500 bogie into a high-tech product that can truthfully be said to be in a class of its own. In other words, a bogie which can offer much more than merely maximum speeds.

Acknowledgements

ICE® is a registered trademark of Deutsche Bahn AG

AVE® is a registered trademark of RENFE

About the author

Christian Küter is Product Manager for Bogies at Siemens Transportation Systems.

He is a graduate of the University of Applied Sciences (TFH) in Berlin and holds a degree in mechanical engineering. After his studies, he joined Faiveley near Paris in 1991 and worked there for two years as Project Engineer for platform screen doors. He then returned to Berlin, switching to project planning for elevator systems at OTIS. Since 2001, he has been in charge of the portfolio for EMU bogies in the Siemens plant in Graz, Austria