German Reichsbahn class 19¹⁰

As the speed of steam locomotives increased, the moving masses of the engine became an ever greater problem. Although this could be partially compensated for with larger and larger driving wheels, the practical limits were reached with a wheel diameter of 2,300 mm. Regular operation could no longer be done above a speed of 400 revolutions per minute, which was achieved with the locomotives of the classes 05 and 61 at around 175 km/h.

The steam motor, which works in a similar way to a piston engine, was seen as a possible way out. Since this had been developed into a compact design in the mid-1930s, there was the idea to develop a steam locomotive like the modern electric locomotives of that time with individual axle drive. Apart from the motors, the locomotive was created according to the same pattern as other express locomotives, since the focus was initially on the steam motor and no further experiments were wanted. The four powered axles each received a steam motor, which was mounted alternately on the right and left outside the wheels. These each had two cylinders arranged in V shape in a 90 degree angle. Since significantly higher rotational speeds were possible here than with conventional steam locomotives, the wheels were designed with an exceptionally small diameter of 1,250 mm.

The boiler of the class 44 freight locomotive was used in order to avoid the development of a new boiler. This was one of the first mass-produced locomotives with a pressure of 20 bars and promised good performance. At the projected speeds, a streamlined fairing was mandatory, and the fairing of the 01¹⁰ didn't need too many adjustments to be used on the 19 1001.

Extensive test runs took place after the somewhat delayed delivery, but due to the war, these mostly took place at speeds below 100 km/h. Despite this, some high-speed braking tests were undertaken, reaching speeds of up to 186 km/h. Although the axles reached almost 800 revolutions per minute, the running smoothness remained in a very good range due to the small moving masses. The disadvantage turned out to be that the drive axles were not coupled to each other and individual axles tended to slip. On a run with a heavy express train, the locomotive once even stopped on an incline.

In times of war, no further attention was paid to further development and the single locomotive was used in passenger service from the beginning of 1943. While it was stored due to a breakdown, it was severely damaged in a bomb attack in October 1944 and was no longer operated. After the end of the war, 19 1001 was taken to the USA together with class 52 with a condensing tender in order to be able to examine the latest German developments there. The Bundesbahn subsequently decided not to buy it back, because even the network, which was still in a poor condition, could not use a single unit that was expensive to maintain for these speeds.