Although the class 170 of the kkStB with the 2-8-0 wheel arrangement appeared to be a freight locomotive, it was developed by Gölsdorf for the increasingly heavier passenger trains on the Arlberg Railway. It had two connected steam domes and two compound cylinders. The second and fourth driving axles could be moved laterally for better running characteristics.

Especially during the First World War, the 170 was indispensable in freight transport. It achieved the highest number of all Austrian steam locomotives and the Südbahn also ordered 54. After the war, the ČSD even had more manufactured and now had a total of 374. Of these, 345 were superheated and simpled, which led to the renumbering from class 434.0 to 434.2. The BBÖ had 228, which retained the Reichsbahn's class number 56 after the Second World War.