The Ol49 was a 2-6-2 passenger locomotive built after World War II to replace older 2-6-2 or 4-6-0 locomotives like the Prussian P 8. It had a driver diameter of 1,750 mm and a top speed of 100 km/h. With good coal, trains of 400 tonnes could be hauled with top speed on the level, while the maximum train weight at 80 km/h was 905 tonnes.
Between 1951 and 1954, 112 were built for the PKP and four for North Korea. An optical feature was the combination of a high pitched boiler and high running boards. In Poland, they got the nickname “Oelki”. Some had Trofimoff valves and some were converted to oil firing. 38 are preserved, some of which have run in preservation.