From 1933, the ČSD had tank locomotives built by Škoda and ČKD for express trains in the mountains. They received assemblies from existing locomotives. The chassis was designed in such a way that curves with a radius of 150 meters or more could be negotiated. When the Sudetenland was annexed, 15 locomotives came to the Reichsbahn and became the class 680. In Czechoslovakia they were only retired between 1973 and 1981. 