Many jobs on the track, such as ballast cleaning for example, generate substantial quantities of spoil. Depending upon the degree of pollution and excavating depth, this can be up to 0,8 m³ per metre of track and often more. Whereas it was common practice earlier to deposit the residue at the side of the track, today the excavated material has to be transported to a suitable disposal site. In many situations, such as in station areas, tunnels or cuttings, it is absolutely essential to load and evacuate the spoil.

In other instances, such as the formation rehabilitation, large amounts of new material are required which the machine has to supply in sufficient quantities.

• Loading, conveying, storing and unloading processes automated for the most part
• Easy adaptation to the prevailing worksite and operating conditions
• No detriment to the working output of the ballast cleaning machine
• Simple operation with minimum number of staff
• Independent power supply
• Positioning solely in the track under construction
• Resulting savings in the worksite management

The MFS material conveyor and hopper units - System Plasser-Knape - fulfil exactly these requirements ideally. They are conveyor lines, hoppers and self-discharging units in one.

The flexible basic concept of these machines enables a constructional adaptation to the most varied operating conditions, both for spoil loading and for the supply of new material. MFS units are available with a storage capacity up to 100 m³, with a varying number of axles and with slewing or rigid front conveyor belt. Special designs are fitted with devices for ballasting the track (for example MFS 100 S) or with a separate drive unit (MFS 40/4-A).

MFS units are open-sided wagons in standard railway vehicle design with a floor conveyor belt in the hopper and a transfer conveyor belt at the front end of the unit.

The floor conveyor belt enables continuous filling of the hopper or passing on the material. The transfer conveyor belt discharges the loose material into the next hopper or to the side at a suitable location. The belt can be slewed 45° to the left or to the right hand side, tilt warning and tilt protection prevents the vehicle from tipping during discharging. A protected workplace with control and monitoring instruments for the conveyor belts is standard design. The MFS units can be put together in any given number to form a material train. MFS units with rigid transfer conveyor belt are used in formation as part of the conveyor line and/or as hoppers. Unloading is performed by an MFS unit in the formation with slewing conveyor belt.

The hoppers are suitable for all kinds of loose material. All conveyor belts are powered hydraulically. A diesel engine supplies the power.

Today, ballast cleaning machines with new ballast supply are frequently in use. In conjunction with these machines, MFS units are used both for loading the spoil and for supplying the new ballast. A typical application of such a machine combination is described as follows.

• The MFS units for spoil handling are pushed by the cleaning machine, the units with the new ballast are towed.
• Transfer of the spoil from the cleaning machine to the first MFS unit.
• The material is passed through to the front unit.
• Continuous loading of the spoil train from front to rear.
• When the front half of the spoil train is full, these MFS units are uncoupled and taken to the disposal site.
• Discharge of spoil and return to the worksite.
• In the meantime the units still coupled to the RM are loaded.
• The emptied MFS units are coupled to the train and the material is re-loaded to the front half of the spoil train.
• Once they are filled, the process is repeated again.
• The new ballast is supplied to the RM from the MFS units at the rear and the unloading is performed continuously from rear to front.

In this way the cleaning machine can work without interruption. The number of MFS units used for the spoil depends amongst other factors on the amount of material to be expected, the distance to the discharging location and the working speed of the RM. The number of MFS units required for the supply of new ballast depends upon the requirement calculated for the prevailing worksite situation.

Material and machine logistics are an increasing challenge, above all on large-scale worksites. To organise the transportation of the material to and from the worksite when operating high-capacity ballast cleaning machines or machines for formation rehabilitation only in the track under construction, a large number of material conveyor and hopper units is needed. In order to deploy these machines even more efficiently in future, an automatic magnetic tape controller was developed for accurate and controlled loading and unloading of the hoppers. There are laser sensors in the front and rear area of the hopper which monitor and control the filling process. This ensures that the hopper unit is filled uniformly. When the loading limit is reached, the laser switches direct the material to the next MFS unit. Therefore, the automatic magnetic tape controller allows the operating staff to concentrate on other tasks. Furthermore, the existing storage capacity as used to the full and this reduces the need for additional units. Retrofitting of existing MFS units is possible at any time, after appropriate consultation with the Technical Customer Service at Deutsche Plasser.

• Storage capacity in worksite operation up to 68 m³
• Two four-axled bogies
• MFS 100 with side slewing unloading conveyor belt
• MFS 100 S additionally with transfer conveyor belt and ballast distributing devices for exact dosage of the ballast into the track or onto the ballast shoulder
• MFSD 100 for unloading solely in the direction of the track axis

The MFS system handles the spoil that occurs during ballast bed cleaning ideally as the material is movable not only within the hopper but also outside the spoil train. Due to the relaying process, intervals between trains can be fully utilised, construction sections re-opened to traffic earlier and the overall annual output of the cleaning machine is also raised. This saves the railway administration operational hindrance costs such as costs for delays, speed restrictions, locomotives and staff.

The cost-efficiency of the application of MFS 40 units for spoil handling in the course of ballast cleaning using a ballast cleaning machine is due to the lower costs on the one hand and due to an increase in output of the ballast cleaning machine on the other. A comparison of the costs of spoil handling using a dumper system including discharge of the spoil on a disposal site, transport of the spoil to the disposal site including return run and maintenance of the required wagons, against the costs of loading and unloading the spoil using three MFS 40 units produces a cost saving of approx. 22% with an annual spoil quantity of 25,000 m³.

(Source: Erwin Klotzinger "Wirtschaftliche Betrachtungen zum Einsatz der Materialförder- und Siloeinheiten MFS 40" in Internationales Verkehrswesen 1/88)

On the Belgian State Railway (SNCB) the application of MFS units was observed in 1988 on several worksites. It was found that the application of MFS units, compared to the use of transport conveyors and high-sided wagons, brought a saving of 49%. The SNCB gives the rate of return on investment for ballast cleaning operations as less than one year. In 1993 the SNCB was already operating 28 MFS units.

(Source: J. Quinet "Utilisation of the Material Conveyor and Hopper Units MFS 40" in Rail Engineering International 4/88)

Only four hours per night are available to Nederlandse Spoorwegen (Netherlands) for ballast cleaning on their lines. This generates enormous quantities of material - around 1.000 m³. 80% of the excavated material is spoil - for comparison: on the DB AG the proportion is 15%.

To handle these amounts ergonomically and cost-efficiency, Nederlandse Spoorwegen procured 20 MFS units. Each of these units holds 33 m³. This helped the Netherlands railways to solve their transport problem.

The material conveyor and hopper units type MFS are well suited for ballasting work:

• Fast loading of ballast material
• Exact dosage and placement of the ballast
• Direct supply to ballast cleaning machines or other distributing machines
• Short term storage of excavated ballast during track and switch renewal work

The Austrian Federal Railways use MFS units during switch renewal and achieve substantial time savings in the site management. Cleaned ballast is inserted into the construction gap from the adjacent track and then consolidated. Furthermore, using this method, the former situation can be avoided that lorries destroy the surface of the formation protective layer when delivering the ballast.

It is also possible to ballast the track using MFS units. For this purpose the front unit is equipped with transfer conveyor belt and distribution devices. By extending a ballast train of this kind with additional MFS units, the capacity can be adapted easily to the worksite situation.

Formation rehabilitation of switches using MFS units may be given as an example here. A bulldozer removes the excavated material and takes it to the BLS 2000 loading station which loads it onto MFS units. The spoil train stands on the end of the track that leads to the switch. After taking away and unloading the MFS units, these are loaded with the material for the formation protective layer and transported to the worksite. The sand is unloaded via the front conveyor belt, distributed by the bulldozer and then consolidated using plate compactors.

But also in conjunction with formation rehabilitation machines such as the SVV 100, AHM 800 series or the PM/RPM series, MFS units perform outstanding services in the supply of FPL material as well as new ballast.

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