TRACK MAINTENANCE engineers from Russia, Bulgaria and Austria are gather beside a siding in the outskirts of the Austrian city of Linz. In front of them stretches a combination of track maintenance machines gleaming in fresh yellow paint.

Focus of interest is an RM801 ballast cleaner just completed in Plasser & Theurer’s assembly plants located in the city’s industrial zone beside the River Danube. Intended for German contractor Deutsche Gleis- und Tiefbau, it has been married up for this demonstration and trial with an MFS240 ballast conveyor and hopper unit destined for Russia. To save the cost of buying a completely new vehicle, the MFS unit has been mounted on a pair of Russian Railways bogie flats equipped to take 1435 or 1520mm gauge bogies. The 29·24m long conveyor unit can be moved independently on the wagons to allow it to negotiate curves down to a radius of 150m.

The RM801 is carried on 15 axles, including a two-axle geometry measuring trailer at the rear which also houses two 3000litre fuel tanks. Designed to clean ballast at the rate of 800 m3/h, the machine is powered by a 1300 kW Caterpillar diesel meeting the latest EU emission standards. The company has built three or four similar machines in the past, but the latest version incorporates ’hundreds of improvements’.

Chief among these is use of a powerful double sieve unit carried on its own bogies so that it can be detached if the ballast is too fouled for reuse or there is no need to recycle it. The ballast is then taken by conveyor straight to an MFS unit for disposal.

Other improvements are tools and power plants that are more accessible for maintenance staff, and use of electronic injection in the diesel engine, which also has its own management system. The rail lifting equipment is able to cope automatically with fishplates on sections with jointed rail.

DGT is currently negotiating with Plasser & Theurer for a formation relaying train similar to an AHM-R train delivered about 18 months ago to Austrian Federal Railways. This has now been fine-tuned to maximise capacity and was tasked in March with relaying a 6 km section of the Linz - Salzburg main line in seven days.

Relaying the formation

Over 750m long, the AHM-R uses separate cutter chains to excavate the top ballast and the formation up to 1·2m below rail level while trains on the adjacent track continue to run - although at reduced speed. This is possible as the working area where the rail and sleeper grid is lifted is less than 20m long, which is short enough for the formation and ballast on the adjacent track not to be disturbed.

The first chain removes the spent ballast under the lifted rail-sleeper grid to a depth of 550mm. The ballast is then taken to a crusher for recycling.

The second chain excavates a further 450mm of formation material which typically consists of fines and degraded ballast that is conveyed forward to a bank of six MFS conveyor and hopper units for disposal. Three of these are kept with the train at all times, but when fully loaded the leading three units are hauled away by a locomotive for emptying, leaving the rear three to load until they return.

Immediately behind the second chain is a chute which delivers the new formation material on to the exposed surface. The material comprises a mix of crushed recycled ballast and fresh crushed stone. This is brought from the rear of the train in small hoppers that are carried on a travelling gantry running on rails fitted on the side of the wagons holding the hoppers.

The mix is directed on to the excavated area where it is at once compacted to a profile chosen to suit the drainage conditions; a geotextile is first laid below it if required.

The sleepers and rails are then lowered back into position. A following ballast train completes the relaying process, and the track, once checked for correct geometry, can then be handed back for normal operations. o

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CAPTION: This RM801 ballast cleaner for German conmtractor Gleis- und Tiefbau (above) was tested in Linz with MFS240 spoil handlers destined for Russia built on old flat wagons able to accept bogies of different gauge (left)

CAPTION: Austrian Federal Railways’ AHM-R includes two ballast cutter chains (left) and a compacting unit (below) which prepares the formation for the track