When the existing 4-6-0 locomotives for mixed traffic could no longer cope with the increasing train loads, new superheated locomotives were developed for pure freight train service, which only had one leading axle. In addition to the 2-10-0 locomotives of the series from number 5.001, 2-8-0 locomotives were developed which were to be given the numbers 4.061 to 4.340.

The boiler was from the 3.1150 series Pacifics and featured corrugated Serve tubes. The Belpaire firebox with inclined grate found its place by locating the fourth domed axle at a greater distance from the third and moving the lower, front part of the grate between the wheels. As was usual with most large French locomotives at the time, a De Glehn type compound engine was used, which acted on the second and third coupled axles. After the steam was introduced into the high-pressure cylinders at a maximum of 16 bars, it entered an intermediate reservoir at 7.8 bars and from there it reached the low-pressure cylinders.

The production initially comprised several series from different manufacturers, which were completed in 1912 and 1913. 1919 followed 20 pieces at Franco-Belge and 1922 another 100 from the SFCM, formerly Cail. The last 40 units only followed in 1928 and 1929 from three different manufacturers and brought the total number of units to 280. Nord-Belge procured 35 identical locomotives, which bore the numbers 421 to 455 and later became the SNCB Type 48.

Sectional drawing with dimensions

Locomotive Magazine, August 1912

The locomotives were given the nickname “Le Boeuf”, i.e. “The Bull” because of their pulling power. They were used in large parts of the Nord network and also pulled pure coal trains. Different models with three axles and a capacity of 17 or 19 m³ of water were used as tenders. The smaller of the two made it possible for the locomotive to use turntables that were 18 meters long. After the First World War, they were also used in front of passenger trains, as the large diameter of the coupling wheel allowed speeds of up to 105 km/h. During this period they also received four-axle tenders of the 140 “Pershing” with a capacity of 22 or 24 m³ and Prussian tenders with 31.5 or 34 m³. Some locomotives later received a Lemaître-type blast pipe, which increased the output by 100 hp. Their decommissioning took place between 1950 and 1959.