As already described for the 01, when the first standard express locomotive was being constructed, it was not yet certain which type of engine would be the best. Thus the 02 was created as an alternative to the 01 in order to be able to compare different designs. While the 01 featured a simple two-cylinder engine, the 02 was powered by four compound cylinders. The 02 was operational even before the 01 and was therefore the Reichsbahn's first standard steam locomotive. With it, the use of bar frames at the Reichsbahn began, with which the Bavarian State Railways had already made good experiences.
Henschel works photo
Die Lokomotive, February 1926
Except for the engine, the two classes were almost identical in order to create the optimal conditions for a comparison. Instead of the two cylinders with a diameter of 600 mm each on the 01, the 02 got two cylinders each with a diameter of 720 and 460 mm. Due to the tendency of this engine to run more smoothly, they were approved for 130 km/h from the start, which was only the case with their sister after modifications.
Sectional drawing with dimensions
Railway and Locomotive Engineering, October 1926
In 1925 and 1926, ten of each variant were built, which were then compared in day-to-day operations at the Erfurt, Hamm and Hof divisions. As expected, the 02 was smoother at higher speeds and slightly more powerful. At cruising speed, consumption was lower than that of the simple engine, but contrary to expectations it was higher at lower speeds.
However, some experts argue that the steam paths of the two locomotives were designed so that their characteristics were more suited to two-cylinder engines. Ultimately, it was concluded that the 01, with its two cylinders, was the better choice for series production. Today it is known that Wagner, who was head of the design department at the time, had a personal dislike for compound steam locomotives and, in his opinion, the more difficult maintenance negated the advantages of lower consumption. With a different design of the steam engine, significantly better power could probably have been achieved, after which the disadvantages of the four cylinders could have been accepted.
Despite the lack of series production, the ten units of the class 02 were still used. However, since they were identical in construction to the 01 except for the engine, all of them were also converted to two cylinders between 1937 and 1942. Up to this point, the locomotives had been in use in the Hof area, where the tests had also taken place. So after the war they remained on the territory of the Bundesbahn and no distinction was made to the actual 01 in operation. The last to be retired was 01 234, former 02 003, on May 8, 1972.