The kkStB class 270 was a 2-8-0 freight locomotive, developed as a superheated variant of the class 170. The actual design work was carried out by BMMF which would later be situated in Czechoslovakia. As usual for Austrian locomotives of the time the superheater surface was relatively small, but the two interconnected domes of the 170 had now been interchanged for a single dome. In result, the class 270 could haul 1,220 tonnes at 60 km/h.

Production started in 1917 but by the end of the war, only 27 had been completed. Production in greater scale only started in 1920 and by 1922, 100 more had been built for the BBÖ. At the same time, 119 locomotives of the same design were built for the ČSD and designated class 434.1. Floridsdorf built a total of 253 for the ČSD, PKP, JDŽ, FS and the CFR. Together with more locomotives built by other manufacturers, the total had reached 574 by 1930.

The locomotives used in Austria became Reichsbahn 56 3401 to 3500 in 1938. After the war, the ÖBB only had 25 left and made them class 156. 15 were later rebuilt with Giesl ejectors and the last ones were used until 1968. The ČSD had received more from the BBÖ, leading to a total of 199. The last one of these was retired in 1976. Also the CFR operated a total of 132, the last ones until 1983. Five had also come to Albania. This wide spreading led to many being preserved in various states, with the ČSD 434.1100 and PKP Tr21-25 still being in working order.