A German steam locomotive. In this case it was driving backwards which is not hard to detect... isn't it? The Deutsche Reichsbahn-Gesellschaft's BR 01 steam locomotives were the first standardised (Einheitsdampflokomotive) steam express passenger locomotives built by the unified German railway system. They were of 4-6-2 "Pacific" wheel arrangement in the Whyte notation, or 2'C1' in the UIC classification. The idea of standardisation was that it would reduce maintenance costs; i.e. if a BR 01 whose engine shop was in, say, Berlin broke down in Dresden, instead of having to ship the necessary part from Berlin and take the locomotive out of service, a part from the Dresden shop could be used as all of the engines, parts, and workings were exactly the same and produced nationwide. Thus it was a "standard" product for engine shops. DRG steam locomotive 01 046 at the former RAW in Frankfurt am Main-Nied in the year 1938 Manufacturer’s plate of 01 118 of the Frankfurt Historic Railway The firms of AEG and Borsig, who were the main manufacturers of these engines, together with Henschel, Hohenzollern, Krupp and BMAG previously Schwartzkopff, delivered a total of 231 examples of this Einheitsdampflokomotive between 1926 and 1938 for the fast passenger services of the Deutsche Reichsbahn. To begin with, 10 locomotives of this class were built with two-cylinder engines for comparison purposes alongside a similar batch of 10 engines of their sister Class 02, which had four-cylinder compounding. Extensive measurement and trial runs were conducted, but after length discussions the controversial decision finally fell in favour of the two-cylinder configuration, which was simpler to maintain but was less powerful and economical than the four-cylinder compounds. The first Class 01 locomotive that went into service was not 01 001, but 01 008, which is preserved today in the Bochum-Dahlhausen Railway Museum. The mass production of Class 01s was somewhat delayed at first because in the 1920s there were neither enough routes with the necessary axle load of 20 tons nor turntables with a large enough diameter. Not until the beginning of the 1930s did the Class 01 become the predominant express train locomotive of the Deutsche Reichsbahn. By 1938 there were 231 locomotives of them available for the prestige express train duties. Another 10 Class 01 engines (01 111, 01 233–241) appeared from 1937 to 1942 as a result of the conversion of the four-cylinder Class 02 locomotives to two-cylinder working. The axle load restriction on many routes was the reason that in the early 1930s a third variant appeared: the Class 03 designed with a two-cylinder engine and axle load of 18 ton, of which no less than 298 were built. In 1939, a three-cylinder locomotive also emerged, the DRG Class 01.10, a further development of the 01. A total of five series or batches were delivered, each with minor variations: 01 001–010 (1926), 01 112–076 (1927–28), 01 077–101 (1930–31), 01 102–190 (1934–1936), 01 191–232 (1937–1938). Even in the 1930s the employment of Class 01s was limited to the relatively few routes that had already been modified to take a 20 ton axle load. From Berlin outwards they were the Anhalt, Lehrte and Hamburg lines. The Berlin City Railway had first to be strengthened by reinforcing the viaduct arches. The first 90 engines were stationed up to 1930 at the locomotive depots of Essen, Nuremberg, Erfurt P, Berlin Ahb, Hamm, Magdeburg Hbf, Kassel, Hanover, Hamburg Altona, Bebra and Offenburg. From 1931 they wre also stabled at Frankfurt (M) 1, Berlin Leb, Braunschweig, Berlin Pog, Schneidemühl, Königsberg, Göttingen P, Paderborn, Dresden Alt, Breslau, Cologne Deutzerfeld, Hof and Halle P. Locomotive 01 118 of the Frankfurt Historic Railway