The Russian SA3 CouplerThe SA3 coupler , an easy and robust design - token in service in the thirties - is well adapted to the large Russian area.
The function of the coupler is easy to understand and repair possible in each workshop. Failures in function are easy to fix and mostly manual to correct. The coupler function - especially in curves and with higher impact speed - is insufficient for European Railway requirements. Even other requirements - for instance disconnection with traction forces between the couplers - aren't fulfilled by the SA3 coupler. For this reason to only the Willisonprofilremained for the European coupler. But the experiences from the Russian designers helped to solve problems especially for function under hard climate conditions.