The Geislinger Steige, opened in 1850, was the first mountain railway in Europe, and therefore locomotives were required which were powerful enough. Thus, in the years 1849 to 1851, Maschinenfabrik Esslingen delivered a series of five locomotives which were specially tailored to this line.

A main feature of the locomotives was that many parts were extra heavy in order to achieve a greater adhesive weight. The solid frame, the saddle under the smoke box and the regulator were all made of cast iron. The wheels were not constructed with spokes as usual, but as cast disc wheels. The firebox had a rectangular plan, as was the case with the type III. The cylinders were inclined and acted on the second coupled axle. Since all three axles were rigidly mounted in the frame, there was increased wear on the rails and locomotives. For this reason, the last three of the five locomotives were given a middle axle without wheel flanges. 

Later there were several rebuilds, which began in 1856 when all locomotives were given a leading axle instead of the first coupled axle and now had the wheel arrangement 2-4-0. However, this did not work out, and so the leading axle was replaced by a bogie a short time later, which changed the wheel arrangement to 4-4-0 and led to the new type designation E. Other major measures included the rebuild of three locomotives, which were converted into 2-4-0T tank locomotives between 1869 and 1875 and designated T 2a. Since the fixed leading axle also became a problem here, a fourth one was rebuilt in 1877 to become a tank locomotive with a 4-4-0T wheel arrangement and a bogie. One of the three previously rebuilt examples was given the same shape in 1881. The latter two were designated T 4a. The service of the last locomotive ended in the 1890s.