Around 1910 it had become clear that the existing locomotives were no longer able to pull heavy freight trains over the Bavarian ramps at sufficient speed. Despite two pusher locomotives, trains could often hardly go more than 20 km/h, which could no longer be described as economical. Thus, Maffei developed a heavy tank locomotive in Mallet construction with two eight-coupled bogies. 

The resulting locomotive was the most powerful tank locomotive in Europe at the time. Since no carrying axles were necessary due to the low speeds on the ramps, the entire mass could be used as adhesive mass. It was able to pull 670 tonnes at 18 km/h alone on a gradient of two percent. At 2.5 percent it could still tow 540 tonnes, which was 100 tonnes more than two examples of the E 1.

A total of 15 of this locomotives were built in 1913 and 1914, and they proved themselves immediately. Both with a single pusher loco behind a freight train or with only one Gt 2x4/4 each as leading and pusher loco, significant increases in the speeds at the ramps were now made possible. After strong competition emerged with the Prussian T 20 in an 2-10-2T wheel arrangement, another ten Gt 2x4/4 were produced in 1922 and 1923. These were revised in many aspects to be even more powerful.

In 1925 and 1926 all engines were modified in order to bring both series to a more uniform and somewhat stronger level. The supplies and the total weight were increased, which now made more adhesive weight available. In addition, seven wheel sets instead of two were now sanded, which was a great advantage under difficult traction conditions. The Reichsbahn took over all 25 engines and classified them as class 96. After the end of World War II, 18 remained, two of which went to the Soviet occupation zone and the rest to the West. The Bundesbahn retired them as a minor class by 1948 and they remained in service with the Reichsbahn until 1954.