Württemberg Tn

To cope with the ever heavier loads of freight trains on branch lines, tank locomotives with five coupled axles were already being used on other railways when the development of the class Tn was started in Württemberg after the First World War. The specifications were that with an axle load of around 12.5 tonnes and suitability for very tight curve radii, a locomotive should be built with the highest possible power. This resulted in the smallest and lightest ten-coupled standard gauge locomotive in Germany, which ultimately had an operating weight of 64.35 tonnes. With full supplies this meant a load of between 12,615 and 12,995 kg per axle.

In order to be able to negotiate curves with a radius of 100 meters or more, the first, third and fifth wheel sets were each designed to be laterally shiftable by 22 mm according to the Gölsdorff system. Due to the small wheels with a diameter of only 1,150 mm, the wheelbase was also shortened, which had a positive effect on running characteristics in curves, but negatively on speed. Since the fourth axle was powered, the connecting rods were very long. Otherwise, the Tn was conventionally designed with a two-cylinder superheated steam engine. In combination with the relatively short boiler, the small tube superheater reached a steam temperature of up to 435 degrees.

Despite their size, the locomotives were relatively powerful with an indicated power of around 770 hp. The top speed of 50 km/h could be reached on the flat with a train weight of up to 1,050 tonnes, at one percent 420 tonnes could still be pulled at 30 km/h. During test runs, 686 tonnes were even transported on this gradient, but only at a speed of 11.5 km/h, which was no longer suitable for everyday use.

All 30 examples survived the Reichsbahn era as class 94¹, but the branch lines were also increasingly being upgraded for higher axle loads during this time. This made it possible to use heavier locomotives such as the class 82 on these lines. These were even more powerful and increasingly pushed the former Tn into the shunting service. After the return of two locomotives from Czechoslovakia, the Bundesbahn had all of them back in stock in 1948. They continued to be used primarily in Württemberg and were finally scrapped between 1959 and 1961 without exception.