An integral part of freight rail transportation is sorting, in the framework of which trains are completed for shipment to one direction or another. Stations at which cargo redistribution is carried out are called sorting stations. In their work, they use many special devices, the main of which is a sorting slide. Let's find out what it is and how it functions.
general characteristics
A sorting slide is a structure located on the territory of a railway station and designed to form or disband trains of freight trains. In fact, it is an embankment on which railway tracks are laid. The design consists of three main sections: the sliding part, the hump and the drainage part. The train is approaching the slide with the help of a locomotive. Then, each car under the influence of gravity rolls to its destination on the lower part, which is located on a slope. Between wagons or trailers rolling down from a hill (several connected wagons), an interval is formed sufficient for the transfer of arrows in accordance with the plan for the formation of trains. The rolling speed of cars is regulated by brake positions, which are equipped with car moderators.
Basic concepts
The top of the hill is called its highest point. Usually its height is from 3.5 to 4.5 meters. Here, wagons or trailers are sent to the podgorny paths to the destination. The height of a hill is called the difference between its peak and the calculated point of the most unfavorable for the slide path. The height is calculated in such a way as to ensure the passage of the car with poor driving performance under adverse environmental conditions to the design point, which is taken with a margin of 50 m from the end of the braking position of the most difficult track. The hump of a hill is called its transverse part, with which the wagon or trailer begins an independent downward movement.
The sliding part is the zone between the last turnouts of the foothill neck of the receiving park and the top of the hill. This zone, as a rule, is equipped with an anti-incline for the convenience of uncoupling of cars and their stopping. The trigger section, respectively, is called the zone between the top of the hill and the beginning of the sorting park. In this section of the path with the greatest steepness is called high-speed.
Types of sorting hills
Hill complexes can be both unilateral, and bilateral. The latter are usually used on particularly large sorting units, with a large amount of work in both directions. Previously, slides were built only in areas with a natural slope of the earth. Many of these slides are still in operation. Later they began to build slides with an artificial slope.
Used methods of braking cars may also vary. It all depends on the point at which the sorting slide is located. Stations that were built near transport hubs eventually found themselves in the city. These sorting complexes have special requirements. We are talking about the silent operation of moderators and switch drives, special dissolution rules and limited access to the station.
Types of sorting parks
The sorting park can be the same in length as other parks of the station, or shortened. Shortened parks are most common in America, where a favorable terrain and large distances between stations allow the formation of particularly long trains. Shortened trains assembled in one sorting park are connected on the departure routes with other half-trains. At the same time, there are cases when it is more expedient to design long sorting parks. It all depends on the specific region.
The latest generation sorting hills provide local control of elements such as arrows and signaling devices of receiving / sending parks, with the ability to check all the necessary closures and dependencies. Less common is the centralized management of the railway, the marshalling yard in particular.
Braking of couplings in a hill zone
The first braking of the cut-off occurs in the hill zone for the formation of succession intervals. It is carried out by one or two TP (brake positions). The next braking is aimed, it occurs in the park area when the car reaches its destination.
In addition to the tick-shaped retarders known at the stations of JSC Russian Railways, other braking systems are also used. For example, at stations located near residential areas, rubber coated rails are used to damp the speed of trains. The frictional force that occurs when a metal wheel moves along a rubber coating is controlled by a moderator. The most promising are the brake positions of the sorting slide, equipped with permanent magnets. They are most effective at high speed of the trailer (more than 20 km / h).
Park braking
In park areas for braking wagons or trailers, a certain number of point moderators are installed that provide quasi-continuous speed control. The most recognized at the moment are point hydraulic piston moderators. They are activated when the wheel flange runs into the retarder piston mounted on the rail neck. If the rolling speed is exceeded (recorded using a special sensor), the excess kinetic energy is extinguished when the piston moves down.
In Europe, a hydraulic spiral moderator has also become widespread. When the car passes along it, the wheel flange comes into contact with the spiral protrusion of the cylinder, the latter makes a revolution, taking part of the energy of the wheel. The resistance that the car moderator will provide depends on how much the speed of the car exceeds the norm.
Braking at stations with a natural slope
At marshalling yards with a natural slope, speed control usually occurs on the entire slope, including the pre-park zone. Slides of the latest generations are equipped with carriages, which are located directly inside the rail track and can be moved using automatically controlled cables. If necessary, the carriager can even bring the trailer to the carriages to which it must join. Such devices are widely used at railway stations in Munich, Zurich and Rotterdam.
In addition to braking devices, sorting slides are also equipped with hydraulic accelerators. They are usually located in the park area and are activated if the trailer moves at a speed below normal.
The first hill systems
The first inclined track for the distribution of wagons was built in Dresden in 1946. At that time, another way to disband trains was spread in Europe - with turntables. In 1858, the first semblance of a hill system was built at Leipzig Station. In the form in which the sorting slide functions today, it was first built in 1863 at the French station Ter Nor.
First anti-incline
In 1876, the first sorting separate station was built at the German station Speldorf with an anti-bias on the sliding part and an intermediate platform. Previously, slides were built on a natural slope, without anti-incline. In 1891, they began to apply the separation of the sorting park into bundles (groups of tracks). Instead of brake devices, brake shoes were then used . These simple devices can still be found at stations with a natural bias.
First moderator
In the twenties, centuries passed in Europe and America began to use a rail car moderator. In 1923, a mechanized complex of four hydraulic moderators was launched at the Hamm European station. Thanks to the mechanisms of electromechanical centralization that appeared around the same time, it became possible to remotely control the railway in the sorting hill section. A little later, the first electrical devices were created that remembered the order of passage of cars. In accordance with the established task, they independently adjusted the beam switch drives.
Full automation
In 1955, the first controllable hill complex was launched at the Chicago station. By the 1970s, most large stations had fully automated sorting slides. A little later, they began to use the radio channel to control locomotives, which allowed to increase productivity.
Alternatives
In the second half of the twentieth century, there was a tendency to the predominance of small freight shipments. Due to increased competition between rail and other types of freight transport, container transportation has become urgent, which allows minimizing the cost of transshipment and taking advantage of each type of transport. In order to reload containers from railway wagons to road and sea transport, special platforms with crane mechanisms were equipped. With the development of container shipments, many marshalling yards in Europe transferred their functions to parks, which can load containers from wagons not only for sea and road transport, but also for other trains.
MSR 32 complex
Siemens has developed a special complex MSR 32 for the construction and modernization of railway marshalling yards. Depending on the type and power of the desired slide, as well as its profile and local conditions, it creates a model that is tested using electronic computers. The model shows where it is most expedient to arrange speed sensors, weight meters, tread gauges, brake positions and other elements of the sorting station.
The system adapts to any customer requirements thanks to a modular device. It is introduced into slides with various profiles, braking concepts and processing abilities. For example, in Zurich, a slide equipped with an MSR 32 system processes 330 cars per hour. The locomotive is controlled by radio. In Vienna, such a separate station has a capacity of 320 wagons per hour. The locomotive of this hill works on radio control. The system provides on all slides a continuous exchange of information with dispatch centers. The operator of the sorting slide should only make sure that everything works as it should. The first village of the former USSR where Siemens installed its technology was Vaidotai station in Lithuania. Gradually, MSR 32 technology is spreading around the world. At the stations of JSC Russian Railways, they are also tested.