The two-cylinder class 43 and the three-cylinder class 44, both with single steam expansion, were the first freight locomotives from the standard program. The 44 was designed to tow 1,200 tonnes on low mountain lines with moderate gradients and 600 tonnes on steep ramps. In addition, ore trains weighing up to 4,000 tonnes should be able to be handled double-headed. With an axle load of 20 tonnes, it could only be used on well-developed main routes.
While the two outer cylinders acted on the third coupled axle, the middle cylinder was installed at an angle and connected to the second coupled axle. Measuring 600 by 660 mm, the cylinders developed considerable power. The boiler was essentially taken over from the 01 and also had a wide firebox, which was above the coupled wheels. The maximum permitted speed was 70 km/h.
In 1926 only ten pre-production machines were built. Since the class 44 consumed a lot of steam compared to the 43 and also had too high an axle load, the decision was initially made in favor of the 43 and no further production of the 44 followed. In 1932 and 1933, the 44 011 and 44 012 were built, their boilers being operated with a medium pressure of 25 bars and with a four-cylinder compound engine. These are not considered optimally designed because the cross-sectional ratio between the high and low pressure cylinders was too large at 2.6. It remained with these two vehicles, one each of which went to the Bundesbahn and Reichsbahn after the war and were used for several decades.
Former Übergangskriegslokomotive as 150 X of the SNCF
SNCF 
Series production of a lighter variant only began in 1937, which only had a cylinder diameter of 550 instead of 600 mm and a boiler pressure of 16 instead of 14 bars. Production peaked during the war to cope with the increased freight volumes. From 1942, probably starting with road number 44 786, production was switched to a “Übergangskriegslokomotive” (transitional war locomotive). Some materials were replaced by indigenous materials and some simplifications were made. This included the omission of the smoke deflectors and the front side windows of the driver's cab.
During the war, other locomotive factories were obliged to build the class 44, including some in the conquered areas. In addition to Fablok in Poland and Frichs in Denmark, these included a particularly large number of French companies. By the end of the war, 1,753 machines for the Reichsbahn had been completed. After the liberation of France by the Allies, production continued there and a further 226 were made. In the GDR, ten were made using boilers that were left over from Frichs.
The Bundesbahn had received the largest part with 1,242 pieces. Although at least 291 machines, most of which were built in France, had to be handed over to France as reparations, the class 44 formed the backbone of heavy freight traffic on the Bundesbahn. The locomotives were given the nickname “Jumbo” and were initially barely changed apart from the replacement of the smoke deflectors. A total of 36 machines were converted to oil firing, mainly in 1965 and 1966, in order to increase performance and economy while relieving the fireman. The oil-fired locomotives were classified as the class 043 from 1968, while the coal-fired locomotives became the 044. The importance of the locomotives decreased when the main routes were increasingly electrified or converted to diesel traction. The decommissioning took place between 1970 and 1977.
Sectional drawing with dimensions
Railway and Locomotive Magazine, October 1926
The Reichsbahn in the east received 335 units, significantly fewer than the Bundesbahn. Of these, 97 were converted to oil firing and 22 to pulverized coal. The unconverted locomotives were taken out of service by 1974 after diesel and electric locomotives were introduced on the low mountain ranges. In view of the oil crisis in the early 1980s, most of the oil-fired locomotives were converted back to coal-firing, but they were rarely used.
After the war, apart from Germany and France, there were 67 in Poland, three in Czechoslovakia, 16 in Austria and one in Belgium. With more than 70 pieces, the whereabouts could not be traced. Today there is still one operational example in Germany and the Netherlands each. 15 more are still preserved, but no longer roadworthy.