The SF 400 bogie

The modular-design SF 400 trailing bogie with air suspension was designed approximately ten years ago at Siemens Transportation Systems’ center of excellence for running gear in Graz, Austria.

This bogie was first used for DB’s high-speed intercity train ICE® 2. Since then, the design has been developed to create a top-class range of universal bogies known not only for their characteristically high degree of riding comfort but also for their exemplary cost effectiveness.

Built for a top speed of 280km/h and the comfort standards of high-speed passenger service and displaying excellent safety characteristics, the SF 400 – ICE had a major hand in the success of that second version of the German high-speed train. A total of 291 intermediate coaches and 22 driving trailers of the ICE 2 fleet were fitted out with the bogie, which demonstrated utmost reliability in day-to-day operations.

Owing to its modular construction, the SF 400 has a relatively simple basic design that makes it suitable for other applications. A major advantage, but one that called for a proportionately high amount of R&D work at the start of bogie development. Extensive theoretical and practical studies were conducted jointly by Deutsche Bahn (DB) and Austrian Federal Railways (ÖBB) and involved, for example, computer simulations in the running gear centre in Graz, test runs on DB’s roller rig in Munich, stationary testing in Minden to determine system parameters, and test runs on lines in Austria and Germany and, later on, even in Switzerland and Italy. Every new vehicle equipped with the SF 400 had to complete comprehensive certification runs prior to commissioning.

In the end, however, this tremendous effort more than paid off, for the goal of creating a modern, powerful and comfortable family of bogies ensuring high dependability and low operating costs was achieved in every respect.

From high-speed solution to double-deck design

The second version of the bogie, the SF 400 DSW, was built for the double-deck coaches commissioned by ÖBB in winter 1997 and demonstrated the vast number of possibilities for this design. The bogie originally designed for high-speed traffic had been transformed into a high-quality bogie for double-deck coaches in rapid transit service. In all, 240 intermediate coaches and driving trailers were fitted with the SF 400 DSW.

Another 20 double-deck driving trailers were sold to Austrian Federal Railways in 2003. An option for 64 intermediate coaches and driving trailers has been exercised and calls for delivery in 2007. Nine double-deckers featuring SF 400 bogies are in operation for the CAT (City Airport Train) that links downtown Vienna with the airport in Vienna-Schwechat and enjoy a very high degree of passenger acceptance.

The utmost in comfort

From the very beginning, the SF 400 running gear family was conceived for the purpose of creating bogies that can offer utmost reliability, performance and comfort within a realistic cost frame.

It is particularly in the area of riding comfort that the SF 400 displays a whole range of exceptional features. For example, the optimum running behavior is ensured by a special wheelset guidance system. To achieve the best possible decoupling of vibration and noise, the primary springs are designed as steel coil compression springs arranged in series with a metal-rubber spring. The secondary springs take the form of an optimized air suspension system that includes a high volume of extra air space. High paths of lateral spring travel ensure optimal comfort in the transverse direction. In addition, essential constructive parameters guarantee high stability and safety against derailment.

Intelligent cost effectiveness

The high-quality, high-comfort design of the SF 400, however, does not prevent the use of intelligent and highly automated production methods, so that the resulting costs are only slightly above those for a conventional steel-spring bogie.

There are many reasons for this. First of all, due to the high bogie quantities ordered, the substantial development costs for the original SF 400 version are negligible today. Thanks to the modular design, the SF 400 family is meanwhile so large that individual bogie tapes can be adopted extensively without change. Should specific customer adjustments nevertheless become necessary, they can usually be carried out with minimum engineering effort.

Intelligent production technology

Highly decisive for cost effectiveness, however, is also the intelligent production technology at Siemens Transportation Systems’ running gear centre in Graz. Optimised in a number of steps over a period of time, the automation process allows, for example, the production of bogie frames with ultramodern welding robots and maximum process safety and efficiency.

The optimised welding sequence eliminates the need for post-welding heat treatment that is usually performed to relieve stresses in the bogie frame.

The machining work is conducted on the finish-welded frame, thus ensuring the observance of very tight tolerances because the effects of welding distortion can be minimised. Our own specially developed jigs and fixtures allow us to keep setting-up times to an absolute minimum, while safeguarding utmost machining precision.

The paintwork, which also contributes significantly to the lifetime of the component, is also applied fully automatically in one of the most modern painting systems for bogie frames.

Maintenance-friendly design

To assess the cost effectiveness of a bogie it is not enough to focus solely on the purchase costs. More and more rail operators who are in step with the times are starting to place more emphasis on life cycle costs in their costing. The SF 400 bogie family is able to reflect their top-class standing in this area as well. Special structural measures applied in the bogie design always kept the central focus fixed on low operating costs during the development phase. Cost-reducing features become especially evident in the area of maintenance and repair.

With 30-40%, wheelset maintenance represents the biggest share of the overall life cycle costs. For this reason, a wheelset guidance system was developed that greatly minimises the forces between wheel and rail and, therefore reduces their wear in comparison with conventional wheelset guidance systems. A split axlebox housing permits wheelset replacement within a minimum of time.

Furthermore, in the interest of easy maintenance procedures, particular importance was placed on the good accessibility of wearing parts and on the unhindered visual inspection of certain components.

As far as technically possible, all parts are secured by means of releasable fastening elements. This facilitates part removal or replacement in the course of maintenance to a great degree, thus also enabling such work to be performed more quickly. In addition, the number of mechanical connections between the car body and bogie were kept as low as possible, which simplifies and accelerates the lifting of the car body off of the bogies.

Bogie maintenance is performed according to the following maintenance stages: visual inspection, main inspection and general overall. The inspection intervals and the life of the components were matched to these maintenance stages.

During the visual inspection and main inspection stages the bogies are checked for mechanical damage, missing or loose parts, function capability, and wear and tear. If necessary, wearing parts such as brake linings are replaced.

Highly compatible interface to the car body

The modular construction and simple adaptation enable the bogie to meet the most diverse application requirements. By varying the interface to the car body (bolster or integral tank), the bogie can be matched to different car body designs.

Bogies from the SF 400 family are being used today in single- and double-deck cars, in intermediate coaches and driving trailers both for mass transit and mainline as well as for high-speed passenger service. Special comfort versions are standard equipment on the DB’s comfort sleeping cars and the ÖBB’s hotel train and couchette coaches.

Cooperation with other rolling stock manufacturers

As of 2006, there are more than 2,000 bogies from the SF 400 family already in operation all over Europe. Thanks to the international orientation of the running gear center in Graz and the readiness to operate company-wide, cooperation with international rolling stock manufacturers constitutes a major success factor. The most recent examples of this are the bogies delivered to our Italian and Swiss partners for the double-deck trains for Trenitalia and for the Swiss Federal Railways (SBB).

Fit for the future

While the SF 400 – ICE bogie first built for the ICE 2 has been proving its reliability for over ten years now, the newest member to the family of SF 400 bogies is once again to be used for a high-speed rail application. Because ÖBB’s new flagship train, the ÖBB Railjet, will also be equipped with the SF 400. Therefore, the people at the running gear centre in Graz are convinced that the SF 400 bogie gives them a highly marketable solution to the future demands of international rail traffic.