SA3 coupler

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1 Short history
2 Operation of this coupler
3 Future
4 See also
5 Sources

[edit] Short history

The factual accuracy of this article is disputed.
Please see the relevant discussion on the talk page. (March 2008)

The simplified scheme of the SA-3 automatic couplers.
Click here for animating

Detail of two coupled SA-3 couplers

SA-3 coupler at the end of the train

In Russia and also in the former Soviet Union, there was a tendency to make equipment that was different from the other countries of Europe, and this included the railway system. The first major difference was the gauge used: "We are a great state, let it be broad gauge!" said one of the Russian rulers to his engineers, in the 19th century.^{[dubious – discuss]} There are a number of stories regarding the selection of this different gauge, but only one seems to make sense: preventing railway transporting of the foreign (occupation) army forces and heavy war equipment from Europe (There weren't more than 100 years after Napoleon) from using the Russian rail system. Therefore the 1524 mm gauge was chosen as the Russian standard. After Stalin came to power in the Soviet Union, all of the member states had to convert all of their tracks to the broad gauge. After World War II, when the Soviet Union assumed control of the Zakarpattia Oblast, the tracks in that region were quickly converted to the broad gauge (In 1947 there were three transshipping stations established at the Hungarian, Czechoslovakian and Soviet tri-borders).

But the gauge difference wasn't enough for Stalin. He wanted more, from the freight transport operation (chain coupler -> 4500 metric tons today, perhaps 3000 metric tons back then), because there was many minerals and industries at the various regions of the former Soviet Union. The efficiency of regular chain coupler wasn't enough. Only a few years before the second world war the Russian engineers created their own version of the Willison coupler.

In the late 1920s, the UIC had established a working group for the replacement of the chain link coupler, which restricts the efficiency of freight railroads in a major way. Many railroads ran prototypes. In Germany, coal trains with Scharfenberg couplers yielded unfavourable results in winter weather, other railroads did similar tests. But the UIC wasn't able, to agree on one replacement. This failure of the UIC, which hampers freight operation in Europe even today, led to the decision of the Soviet Union, to move forward without a standard being achieved in the talks.

The coupler was named SA-3. This type of coupler has been standardized for the railways in the Soviet Union, after the World war II.

[edit] Operation of this coupler

The benefit of this coupler: About 5000-6000 metric tons heavy could be hauled. But this is was a good impulse for the Soviet industries, because the transport capacities has been doubled.

Helper locomotives at the end of the trains are rarely used in the countries of the former Soviet Union. The amount of the freight per train is not as great as in the American countries. This is caused by the 3 kV DC electrification system. Most of the catenary in the former Soviet Union are fed with 3 kV DC and its construction (except some lines around Moscow) doesn't allow more than 6000 kW per electric section (one locomotive has power effort from 3000 to 6000 kW).

Although the SA-3 coupler is primarily used in the countries of the former Soviet Union, they are visible everyday at the transhipping stations, on the eastern borders of the European Union (Poland, Slovakia and Hungary). Since bogie changing-technology has progressed, this allows for cars with SA-3 coupler to regulary operate on the standard gauge tracks. A special car is inserted between standard and broad gauge cars for this operation, with different couplers (SA-3 and standard) on each end. Although these coupling freight cars (light blue coloured at the Slovak Cargo Railways) has a place for load, they are operated always empty.

The mostly Slovakian broad gauge railway between Košice and Uzhhorod, Ukraine utilizes SA3 couplings exclusively. The railway allows for ore and coal transports from Kryvyi Rih, Ukraine to the US Steel mill in Košice and coal to the power plant of Vojany.

In addition, the heavy iron ore trains on the Swedish Malmbanan began to use SA3 couplings in 1969 after problems with snapping chain couplers and a need for ever increasing capacity with higher train weights. Today, IORE locomotives hauls 68 120-ton carriges with a total weight in excess of 8000-ton over gradients of 10 permille and in harsh weather conditions, from the LKAB-mine in Kiruna to the ice-free harbor of Narvik, Norway with this couplings and without any problems.

[edit] Future

The new European Automatic Center Coupler (C-AK) has been based on this coupler, with the extended features of automatic brake and electric couplings. It also has vertical stability added, so that the coupling can't fall down and damage the tracks or causing a derailment. It is compatible with the standard SA3 coupler and has the buffers needed for use with the standard chain couplings.