SA3 Coupler - Operation of This Coupler

Operation of This Coupler

The benefit of this coupler: About 5,000–6,000 tonnes (11,000,000–13,000,000 lb) could be hauled. This was a good impulse for the Soviet industries, because the transport capacities were doubled.

Helper locomotives at the end of the train are rarely used in the countries of the former Soviet Union. The load of the freight per train is not as heavy as on American railways. This is due to the 3 kV DC electrification system. Most of the catenary in the former Soviet Union is fed with 3 kV DC and its construction (except some lines around Moscow) does not allow more than 6,000 kW (8,046 hp) per electric section (one locomotive has power effort from 3,000 to 6,000 kW or 4,023 to 8,046 hp).

Although the SA-3 coupler is primarily used in the countries of the former Soviet Union, they are visible every day at the transshipping stations, at 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 regularly operate on the standard gauge tracks. A special converter car is inserted between standard and broad gauge cars for this operation, with different couplers (SA-3 and standard) on either end. Although these coupling freight cars (light blue coloured at the Slovak Cargo Railways) have room for cargo, they are always operated empty.

If the vehicle fitted with the SA3 retains its buffers, then a special adapter allows that vehicle to couple to another vehicle fitted with buffers and chains, provided that the buffers have the same spacing or gauge. This appears to be done in Iran.

On the Uzhhorod - Košice broad gauge track between Košice and Uzhhorod, Ukraine, of which the major part is on Slovakian territory, SA3 couplings are used exclusively. The railway is used 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 2008, this line is to be extended into Austria.

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 haul trains of 68 hopper cars of 120 tonnes (260,000 lb) with a total weight of over 8,000 tonnes (18,000,000 lb) over gradients of 10 per-mille (1%) in harsh weather conditions, from the LKAB mine in Kiruna to the ice-free harbour of Narvik, Norway using couplings of the SA3 type without any problem. The earlier SJ Dm3 locomotives have buffers fitted, therefore they can couple with cars (or locomotives for transportation purposes) with chainlink coupler.

Worldwide, the heaviest trains, of around 30,000 tonnes (66,000,000 lb), operate with AAR coupling. The SA3 is not used for such loads—the European single locomotive haulage record stands at 12,000 tonnes (26,000,000 lb), by a British Rail Class 59. New railways are mostly electrified at 25 kV AC, which allows higher power than 3 kV DC, so records may yet be challenged. New international links may also see the SA3 and AAR coupling meet and it is unknown how this break-of-gauge will be resolved.