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SFM Compact

Optimum track finishing

Ballast regulation, stabilisation, compaction, surface homogenisation, dust removal – combining all these work sequences for comprehensive track maintenance provides the perfect track surface for high-speed lines.

For many years, Japan has been demonstrating the potential of the railway system in terms of high-speeds, punctuality, and safety. Not only do trains on the Japanese high speed network reach top speeds, but also high average speeds of more than 200 km/h. Separating the high-speed network from commuter and main-line services has proven to be beneficial. Enclosing the lines almost completely with fences, using robust technology, and, of course, high-quality maintenance creates added value.

Since the end of 2021, a new machine - the SFM Compact - has been available for track maintenance. This machine’s concept is based on the SFM 20, which has been operated in Japan together with the SES 170 sleeper exchange system since 2016. After sleeper exchange, the SFM 20 was used behind the tamping machine to restore the perfect track surface on high-speed lines.

The new, continuous-action SFM Compact also combines several work sequences for optimal final treatment of the track surfaces after tamping work is completed. The ballast bed is profiled and homogenised in one pass – the perfect preparation, especially on Japanese high-speed lines, where the machine is used. Several additional functions have been implemented on the new SFM Compact: a digital recorder, a DGS dynamic track stabiliser, and high-pressure water spraying units.

The plough unit at the front of the machine is used to precisely produce ballast shoulders and to systematically distribute existing ballast. The special design of the frontal plough also enables ballast distribution in the area of the guard rail. Special transverse brushes ensure crosswise ballast transport and the placement of ballast in the inner tamping zones.

A homogenised ballast structure

Two integrated stabilising units increase lateral track resistance of the track panel after maintenance operations, making track geometry more resilient thanks to a targeted initial settlement of the ballast. One of the two stabilising units is equipped with variable impact force. This makes it possible to control track settling and to produce smooth transitions. A digital recorder logs and documents the work results.

Finally, a sleeper-crib consolidator and a sleeper-end consolidator homogenise the ballast bed to prevent flying ballast stones.

Safe control from the cabs

The workstations are located in spacious and quiet cabs, offering ergonomic and safe control of all functions from the operator's seat. The work units are operated via a touch screen and a multifunction button with a logically structured user interface.

The ploughs are controlled directly by joysticks from the cab, which offers maximum visibility. An adjustable or automatic obstacle control supports the operator in precisely lifting the work units. The automatic re-railing assistance of the work units is another feature that makes work easier and, above all, ensures the machine is put into operation safely from the cab.

Sweeping and washing: the finishing touch

A well-proven sweeping unit fills the sleeper cribs with ballast and discharges surplus ballast via a transverse conveyor belt onto the left or right ballast shoulder. During a first high-pressure washing cycle, dust is removed from the rails directly behind the sweeping unit. A fine sweeper brush and rail fastening brushes remove any remaining ballast stones. The last high-pressure water spraying unit applies a perfect finish to the sleeper surfaces.

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