Since people in Württemberg were not satisfied with the performance of the 4-4-0 locomotives, such as the old type B, they started building machines with the 2-4-0 wheel arrangement in 1868. Due to the larger axle loads that were now possible, it was possible to install a larger boiler even with three axles. The first model of this type was again given the type B, but was classified as type B 1 from the following year.

A feature of the locomotives was the Crampton boiler, which overhung the closely spaced wheels at both the front and rear. Due to the short wheelbase, it was possible to do without flexibly mounted axles. However, since this had a negative effect on the running characteristics, the distance between the coupled axles was increased on later machines such as the type A. There were two steam domes that differed in size significantly. They also had a Prüsmann-type chimney, which, with its long, slender and slightly conical shape, remained a feature of many locomotives for many decades. In addition to the wheel housings, the internal Allan valve gear contributed to the already very tidy appearance of the machines.

A total of 86 examples were built by 1878, which were later also referred to as B 2. Although some locomotives were rebuilt to the Ab class in the last decade of the nineteenth century, the last of the unmodified machines remained in service until 1913.