After the end of the First World War, in the course of the founding of the Weimar Republic, it was decided to place the Länderbahnen (state railways) under a joint administration. Thus, on April 1, 1920, the “Deutsche Reichseisenbahnen” (“German Imperial Railways”) were officially founded, which was soon renamed the “Deutsche Reichsbahn”. Due to the Dawes Plan, the Reichsbahn was privatized in 1924 and called the “Deutsche Reichsbahn Gesellschaft” so that its profits could be paid to the victorious powers as reparations.
A major challenge was to manage and effectively use the large number of different steam locomotives of the state railways. Although many of the locomotives were still state-of-the-art, their different properties made planning the ongoing operation more difficult. In the long term it was therefore necessary to standardize the vehicle fleet.
First, some particularly successful Länderbahn locomotives were procured by several Reichsbahn departments, such as the Prussian G 12. The Prussian P 8 and the Bavarian S 3/6 were also built for a few more years. When there were surplus locomotives in certain areas of work, the oldest machines of the Länderbahnen or those that were only available in small numbers were taken out of service first.
To manage the individual types, a class scheme was drawn up that assigned a number from 01 to 99 and possibly a sub-class to each type. The lowest numbers in each area were reserved for the new locomotives. On the other hand, many older locomotives were assigned a number, but they were no longer re-numbered on the key date in 1925 because they had already been retired.
The following numbers were assigned for different categories:
01-19 Express tender locomotives
20-39 Passenger tender locomotives
40-59 Freight tender locomotives
60-79 Passenger tank locomotives
80-96 Freight tank locomotives
97 Rack tank locomotives
98 Local railway tank locomotives
99 Narrow gauge locomotives
Express train tender locomotives of the regional railways with the wheel arrangement 4-6-2 (Pacific) were sorted into the class 18. For example, the Saxon XVIII H became the class 180, i.e. with numbers from 18.001. The Bavarian S 3/6, which was available in large numbers, was given the number range 184-5, i.e. with numbers between 18 401 and 18 548. The Reichsbahn received almost 3,000 units of the Prussian P 8, these were given running numbers from 1001 and became the class 3810-40.
The standard locomotive program was created for the construction of new locomotives. The aim was to develop the largest possible number of classes for different fields of application with a large number of identical parts, economical production, simple maintenance and a long service life. Richard Paul Wagner, who was head of the design department from 1922, was in charge here and shaped many of the basic features of the standard locomotives.
A central element was the bar frame, which Wagner was able to experience on his study trips to the USA and which the Bavarian State Railway had also used. Due to its lower overall height, one had a freer hand in the design of the boiler and could use a firebox with more advantageous proportions. Even the driver's cabs, smoke deflectors and other externally visible assemblies showed at first glance that this was a standard locomotive of the Reichsbahn. Inside, for example, the steam paths were optimized in order to optimize performance and consumption without much effort.
In order to reduce production costs and simplify maintenance, compound engines were not used and the higher consumption was accepted. This was preceded by test runs with the class 01 express locomotives with two-cylinder engine and class 02 with four-cylinder compound engine. Since the 02 was only marginally more fuel efficient, the additional cost of the engine was not considered justified. Some have argued that the 02's engine was deliberately under-designed to achieve the desired result. The use of a third inner cylinder with simple expansion was also avoided as far as possible and only implemented in locomotives that required particularly smooth running at high speeds or high loads.
It was noticeable that the boilers of the standard locomotives were very long. The lack of a combustion chamber resulted in excessively long smoke tubes, which caused problems due to stresses with temperature differences. Later, the boilers were made of the harder steel alloy St 47k, so that they could be operated at 20 or even 25 bars instead of 16 bars. Later, the pressure had to be reduced again, as it was only recognized later that this steel became brittle over time and dangerous hairline cracks formed.
In general, innovations in steam locomotive construction often did not catch on with the standard locomotives in order not to have to modify the production facilities designed for mass production too much. Especially with the induced draft system, the traditional design was retained and no variable, cloverleaf-shaped or Kylchap blastpipes were used. They refused to install mechanical stokers to feed the grate and therefore relied on the muscle power of the firemen. With the most powerful locomotives, it was not uncommon for two firemen to be used at the same time in order to be able to shovel enough coal.
In the 1930s, the steam locomotives had to prove themselves against the new multiple units such as the “Flying Hamburger”, which easily reached high average speeds on routes with low traffic volumes. One result was the class 61 tank locomotive, which was designed to haul light passenger trains at speeds of up to 160 km/h. In general, many streamlined locomotives were built in the 1930s, which should consume less at high speeds. The fairing soon proved to be a hindrance to maintenance and caused some chassis components to overheat, which is why it was later removed.
In 1937 the Reichsbahn was nationalized by the National Socialists so that they could better use it for their own war plans. With the beginning of the Second World War, development in the area of express locomotives was virtually stopped and greater emphasis was placed on the mass production of freight locomotives. On the one hand, production of the heavy class 44 was only really getting going at this point, on the other hand, locomotives with low axle loads were being developed for use in the conquered territories.
One of the central points was the simplification of the production of existing locomotive types and the rationalization of production. The Gemeinschaft Großdeutscher Lokomotivfabriken (“Association of Greater-German Locomotive Builders”) was founded in order to manufacture different assemblies in individual plants and then assemble them in another plant. The simplification of the locomotives led first to the transitional wartime locomotives (“Übergangskriegslokomotiven”) and then to the wartime locomotives (“Kriegslokomotiven”), in which many parts were made more simply and other parts that were not necessary for operation were omitted. The resulting higher consumption was accepted. The service life of the individual locomotives could also be shorter, since they were considered dispensable after the expected victorious end of the war.
After the German defeat, it quickly became apparent that the railways in the western and eastern zones of occupation would soon separate. In the GDR, the name “Deutsche Reichsbahn” was continued, while in the FRG the Deutsche Bundesbahn was founded. Both sides first had to make ends meet with the material they had and repair the damaged infrastructure and vehicles. Only after a delay was it possible to produce new locomotives in large numbers.
Due to the accommodation of the victorious powers, the Bundesbahn was able to decide early on to switch to diesel and electric locomotives on a large scale. As a result, only a few new steam locomotives were developed and manufactured. Nevertheless, for some time one was dependent on the existing steam locomotives and had to extend their service life. Major work was needed on the wartime locomotives, which were of inferior quality, and on the boilers made of the problematic St 47k alloy. Many locomotives received completely new, welded boilers with combustion chambers, which increased performance.
The Reichsbahn in the GDR was in a much worse situation, as the Soviet Union demanded large reparation payments. For example, all functioning electric locomotives had to be handed in and all overhead lines were dismantled and taken to the Soviet Union. The second track was also dismantled and removed from double-track lines, and many industrial plants were generally dismantled as reparations. Thus, the Reichsbahn had a much more difficult start and a large-scale electrification or the construction of diesel locomotives was not foreseeable.
The focus was now on keeping the existing steam locomotives operational for several decades. After many locomotives had already undergone major modernizations, the Rekolok (“reconstructed locomotive”) program was launched in 1957. The locomotives were rebuilt from scratch, with new high-performance boilers also being used. Since the GDR could not obtain high-quality hard coal in large quantities, the boilers had to be designed for the use of lignite. This resulted in the 015 class, for example, which achieved significantly increased performance compared to the original 01.