The Pt 2/3 was a tank locomotive that was developed for lighter passenger trains and was delivered by Krauss a total of 97 times between 1909 and 1916. It prevailed in testing against the Pt 2/4 N.

Thanks to a superheater, it was now possible to build small locomotives with the simple 2-4-0T wheel arrangement that were still powerful. However, this arrangement of the axles was not derived from the classic 2-4-0 passenger locomotive, but was more in the tradition of the 2-2-0T branch line tank locomotives with a long wheelbase. By adding another coupled axle that can be shifted laterally by 25 mm at a minimal distance from the driving axle, a radially adjustable leading axle could be dispensed with. With this arrangement, a lightweight construction of the locomotive was possible, which consequently also reduced consumption and thus operating costs.

As with other smaller Bavarian tank locomotives, there was a passage at the rear. In order to save costs, the fireman had to take on the role of conductor at the same time. Later, the passage was eliminated in favor of a larger coal box. Another change, which was carried out until 1937, was the exchange of the rigidly installed leading axle for a bissel axle. 50 of the engines were converted in this way and now had the UIC wheel arrangement 1'B instead of 1B.

In 1925, the Reichsbahn included all the engines built as numbers 70 001 to 70 097 in their inventory. After the war, the Bundesbahn took over all 89 remaining examples and used them in southern Germany. Due to their economic efficiency, they remained in use for longer and so the last one was only retired in 1963. Today only road number 70 083 is still operational. Four examples remained in Austria after the Second World War and were used by the ÖBB as class 770. One of these was used in Austria from 1999, but has now been taken to a museum.