To address the lack of locomotives after World War I, the Belgian State Railways ordered 150 Consolidations from the USA in 1919. The diameter of the drivers was large enough to make them also suitable for passenger service. Generally designed after American practice, these locomotives were tailored for service in Belgium and not only had a Belgian-style cab, but also a tender that was entirely built from Belgian blueprints. Every part of the design was carried out in metric measures. The order was split evenly among ALCO-Schenectady and Baldwin.

The first locomotive was completed only 52 days after the sales representative arrived back in the USA. In contrast to the Pershing class built by Baldwin, they had a wide firebox, what necessitated a boiler that was mounted higher above the drivers. The last five built by ALCO had also received a Worthington feed water heater. In service, even the locomotives without a feed water heater were able to haul a 1,000-tonne train up a 0.5 percent incline at 42 km/h. In addition to the American Consolidations, Armstrong Whitworth built 200 more of their own design for Belgium which were designated type 31 and were less successful than the American locomotives.