The class 11 of the Bulgarian State Railways was a 4-10-0 locomotive for heavy mixed traffic. As a part of the Bulgarian standard program, they were heavily influenced by the German standard locomotives of the Reichsbahn. Like most Bulgarian standard locomotives, they had three cylinders. Thanks to the first driving axle being laterally movable, they could negotiate curves with a radius of 140 meters.

The first ten were built in 1941 and 1942 by Henschel. Two other batches of five and seven were ordered from Škoda and Borsig. Due to relocation of production capacities in favor of the war locomotives, the order for Škoda was cancelled. Thanks to the close relationship between Germany and Bulgaria, the order for Borsig was built anyway.

After only a few years, they were only used in freight service. By 1965, they got a mixed coal and oil firing. Even though they were not very popular with their crews, they were only replaced by diesel locomotives around 1970. In 1975, they were officially retired and scrapped.