DRG BR 39

The Prussian State Railways' class P 10 were 2-8-2 "Mikado" type passenger-hauling steam locomotives built for hauling heavy express trains in hilly and mountainous terrain. They were the last Prussian steam locomotive design before the incorporation of the Deutsche Reichsbahn Gesellschaft (German State Railways), who designated them BR 39 (Baureihe, or series, 39).

The design, by Borsig under the supervision of chief engineer August Meister, was ready in 1919, but due to materials shortages no locomotives were produced until 1922. A total of 260 of these locomotives were ultimately constructed. They were three-cylinder locomotives, all of which drove on the second coupled driving axle. Three sets of Walschaert valve gear were used, that for the inside cylinder being mostly between the frames but driven from the same left-hand side eccentric crank as that side's valve gear; two eccentric rods of different lengths were attached to the same crank.

The locomotives' heavy axle-loads exceeded the 17 tonne standard specification of much of the German rail network, so they were limited to specific lines which were constructed to higher standards. They were primarily put to work on the Main-Weser-Bahn between Frankfurt and Kassel.

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