Prussian P 4²

The first two examples of the P 4² came from the series of eight trial locomotives that were already described in the article of the P 4¹. In contrast to the latter, they were powered by a two-cylinder compound engine, but otherwise they were largely identical.

Similar to the P 4¹ of the Erfurt variant, two P 4² of the Erfurt variant were built, which were delivered by Henschel in 1891 and took part in the testing of the different types. Since at that time there were still massive starting problems with compound engines with two cylinders, priority was given to the simple engines despite their poorer efficiency, so that no further P 4² of the first type were manufactured.

The problems could be solved after the Union foundry in Königsberg invented the Dultz starting device, which enabled the vehicle to start in any wheel position. Thus, in 1898, the production of a normalized design began, of which a total of 707 examples were to be built by 1910. Despite the only slightly increased weight, these were not only more economical than the P 4¹, but also more powerful.

Like its predecessor, the P 4² was used in front of express trains, especially in the early days, but was later pushed out of this role by new locomotives. Mecklenburg, Oldenburg and the Lübeck-Büchener Eisenbahn also procured these locomotives, although the latter had ordered a variant with a shortened wheelbase. These reached quantities of 31, eight and five.

Of the 549 engines recorded in 1923, 437 were taken over by the Reichsbahn in 1925 and assigned the numbers 36 002 to 36 438. Most examples were retired by the start of World War II, but some returned from eastern areas during the war. Of the locomotives which survived the war, one was equipped by the Reichsbahn with coal dust firing and received a four-axle tender with 30 m³ of water. It was only retired in 1959 and was thus the last P 4².