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Muhr Railcar Dumping Systems used for the Longest Railway Tunnel in the World

Author: Martina Grandauer

For unloading railcars containing building and cut-out materials coming up in vast quantities during construction of the Gotthard base-tunnel, Erhard Muhr Pvt. Ltd. has developed, designed, produced, delivered and assembled railcar dumping systems.

At present, one of the most important infrastructural projects in Europe is under construction: the Gotthard base-tunnel. The object consisting of two tunnels has got a total length of about 57 kilometers and leads from Bodio in Ticino to Erstfeld in the Swiss canton Uri. It is supposed to be finished by 2014.

On site of the various roadworks of the Gotthard base-tunnel, vast quantities of building and cut-out materials have to be handled. The high-grade cut-out material is worked up for recycling and used for the production of about 5 million tons of concrete additives. The refinement is done directly on site, in the processing plants at Amsteg, Sedrun, Faido and Bodio.

For transport of the cut-out material particular railcars are used. At Sedrun e.g., a total quantity of 3.7 million tons of material is carried from the haul bottom to the level of the access tunnel.

The rock coming up daily is charged to 150 building trains, each 120 meters long.  Unloading of the railcars requires specific technology.

Here, railcar dumping systems ensure economic unloading, as they help avoiding  unnecessary manoeuvring.

The railcar dumping systems produced by Erhard Muhr Pvt. Ltd. are high-performance facilities best-suited for any unloading of bulk materials. Particularly qualified for quick, automatic unloading of trains with open railcars. Outlined on customer specifications, this cost-effective unloading equipment for versatile use may be applied for special operations, too. 

The company received the order to develop, design, produce, deliver and assemble a rotary-type dumping system with two tippling lines at Bodio, and a turnover facility at Sedrun.

Under difficult meteorological conditions, assemblies began early in winter 2002. The first test runs and start-up were successful and thus hand-over of the plants at Sedrun and Bodio to the customer was possible according to the agreement . The turnover system at Sedrun was ready for operation 14 days after start of assembly. The rotary-type dumping system at Bodio has been working successfully and smoothly since the beginning of this year. Till today, more than 1,000 dumping operations have been done there without any problem.  

Rotary-type dumping system at Bodio

The rotary-type dumping system at Bodio has been installed overground in a hall. The cut-out material from the gravel haul is to be discharged onto a band conveyor which is positioned in a hopper beneath rail level and will transport the material  on to refinement. The small overall height and diameter obtained by the L- shaped geometry of the rolling segments, together with the segmental design, allowed the use despite limited space.

The two rotary-type dumping units of type L-Tec 5-25 at Bodio are suited for discharging 5 railcars of type Mühlhäuser Rota-Car, each containing 25 m³, at a time. Dumping times and tonnages were adjusted to site-specific requirements: one unloading operation takes 9 minutes for 2 x five railcars, each containing 25 tons of material. As only one person is necessary for operating the plant, quick and reliable train returns are guaranteed.

The total plant consists of six rolling segments with a spacing of one railcar in- between. 

On the rolling segments, the rolling bridge including the railcar is swivelling.

As the plant segments are open at the top, there is no limitation in height for the engines. The L-Tec system may also be passed by electric engines, and uncoupling of the railcars during discharging is not necessary. 

After the train has entered the rotary-type dumping unit by means of uncomplicated rough-positioning by the conductor with an accuracy of 1 meter only, the fine adjustment of the railcars on the rolling bridge is done automatically by a hydraulic displacement facility.

After determination of the position, the wheels of each railcar are clamped hydraulically by the lower car-clamp.  

At the same time, the upper edge of the dropside of each railcar is clamped to the rolling segments by means of hydraulic car-clamps fixing the railcar in its position during rotation.

Then the rotation for unloading is started.

The rolling bridge is driven at each rolling segment. The rotary drives are driven electrically, the displacement facility as well as the car clamps are driven hydraulically. Energy consumption for the rotation is very low, as the centres of gravity are in a balanced position.

As all the components, like e. g. rotary drive, pinion, rollers and hydraulic aggregate, were built in at a well-protected and accessible position beyond the flow of bulk material and above both, dumping level and hopper, the flow of bulk material is neither restrained nor narrowed, and the few maintenance works required may be done easily.

After unloading, the railcars are turned to their initial position and all the hydraulic clampings are released.

Turnover system at Sedrun

At Sedrun, the cut-out material is hauled through a shaft from a depth of about 800 meters to the level of the access tunnel and transported to the place of installation at Las Rueras. The content of the railcars is dumped into a hopper by the turnover system of type L_high-Tec, whose upper edge is positioned at rail level, and transported by an output conveyor to a crushing machine refining the material to concrete additive.

At Sedrun, no expensive underground works were necessary. Independent design of the hopper and output conveyor was possible, as the turnover unit was set up at the same level as the rails, and the dumping level is positioned about 1.50 meters above this level.

The turnover system of type L _high-Tec at Sedrun is intended for unloading railcars of type Mühlhäuser Rota-Car, each containing 12 m³. By one dumping operation a minute, 25 tons of material are discharged. Dumping angle, dumping rate and tonnages were adjusted to site-specific requirements. Here, too, the open-top design does not limit the engines´ height.

The turnover facility is lifting the railcar and unloading the cargo in parallel to the rails in a bow movement. 

After positioning of the wagon on the hydraulic wagon turnover unit, the wheels are fastened hydraulically. At the same time, the upper edge of the wagon dropside is clamped hydraulically to the wagon turnover facility. Then, the tilting movement for discharging is started.

After unloading, the railcar is tilted to its initial position and the hydraulic clampings are released.

By means of a reliable hydraulic drive and the favourable mechanic design with only one pivot and low torsional moments, turnover systems of type L_high-Tec are - compared to dumping systems with gear rim-drive - extremely wear-resistant and low-maintenance. The drive was built-in at a well-protected and accessible position beyond the flow of bulk material and above the dumping level. Any maintenance work required may be done above the hopper.

Minimization in weight makes this turnover unit transportable and easy to assemble; thus, it may be used at another location without any problem after completion of works at Sedrun.

Technical data L-Tec rotary-type dumping system at Gotthard-Bodio

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