To accelerate freight traffic, the Soviet railways designed the ФД (FD) in the late twenties. It was named after Felix Dzherzhinsky, a communist revolutionary. In comparison to earlier 2-10-0 freight locomotives, it was a 2-10-2 with a large grate to burn low-grade coal. Design was carried out by the 1-5-1 project group in only 170 days. The first prototype was completed in 1931, but was not ready yet for full-scale production. At this stage, additional input came from the ten 2-10-2 and 2-10-4 series T locomotives imported from Baldwin.
So the production locomotives had a bar frame, integrally cast cylinders, Boxpok wheels on the main drivers and a steel firebox with combustion chamber. Additionally, the four-axle tender of the prototype was changed for a six-axle tender with a mechanical stoker to feed the grate of seven square metres. To facilitate curve negotiation of the five driving axles, the first driving axle and the leading axle formed a Krauss-Helmholtz bogie. Although the main production variant had an axle load of 21 tonnes, it was designated ФД 20.
Some parts of the ФД were also used in the ИС 2-8-4. In 1939 two were built with a large condensation tender that would have allowed non-stop runs of more than 1,000 km, but this idea did not catch on due to complicated maintenance, too much wear on some components and the greater weight. What was more successful was the ФД 21 that was created by using a new type of small tube superheater instead of the old superheater with wide tubes. Of 3,213 ФД built by 1942, 323 were of the ФД 21 type.
In war times, they were used in the Ural Mountains with trains of 4,000 to 5,000 tonnes, although their train load was usually limited to 2,000 tonnes. To reduce their axle loading, 85 were rebuilt into 2-10-4 locomotives in 1943. These were designated ФДP18, what denoted their axle load of 18 tonnes. When many lines were upgraded, this was undone.
After the war, the ФД was used as a basis of the new types Л, ЛВ and ОР21 and the Chinese QJ. Between 1958 and 1960, when the Soviet Union started to build diesel locomotives and the production of the QJ in China was not as fast as needed, around 1,000 ФД were donated to China and re-gauged to standard gauge. Some also went to North Korea. Most were retired in the Soviet Union in the sixties, but China used them until the eighties. Many have been preserved, with four still in working condition.
