SA3 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.

In Germany, coal trains with Scharfenberg couplers yielded unfavourable results in winter weather, other railroads did similar tests.

This failure of the UIC, which hampers freight operation in Europe even today, led to the decision by the Soviet Union to move forward without a standard being achieved in the talks.

Since bogie exchange technology has progressed, this allows for cars with SA3 couplers to regularly operate on the standard gauge tracks.

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 composition consisted of 439 coal wagons and several diesel locomotives distributed along the train with a mass of 43,400 tonnes and the total length of 6.5 km (4.0 mi).

At the end of the 1990s SAB WABCO (now Faiveley Transport Witten) restarted development of a coupler on mechanical SA3 scheme.

The C-AKv was a strong candidate for a common European automatic coupler as a joining successor on the Eurasian continent.

During the preparation for a common digital automatic coupling (DAC) in the EU, there was another SA3-compatible coupler contributed by CAF, but it was not chosen.