The IX was an express locomotive of the Crampton type, which was originally to be built as a freight locomotive and underwent a number of modifications before it was delivered to the Grand Duchy of Baden State Railways. Also due to the very rapid development at that time, the locomotives differed depending on the year of construction.

The characteristics of a Crampton locomotive were immediately apparent. These included a low-lying boiler mounted approximately midway above the two leading axles and a single driving axle with very large wheels located behind the boiler. This design offered great smoothness at high speeds, but only a low friction weight.

Since a broad gauge of 1,600 mm was initially used in Baden, the class IX was also designed for this gauge during its development phase. However, because between 1854 and 1855 all lines were changed to the standard gauge of 1,435 mm, later locomotives were also built with this gauge. 

Comparison of the first design with a chimney located to the rear and the fourth series from 1863

Die Lokomotive, September 1909

Another change before commissioning was the installation of a normal smoke box with the chimney at the front end of the boiler. The first two engines “Adler” and “Falke” had received a return flue from the factory, which means that the chimney was located in the middle of the boiler and thanks to the shorter steam tubes, the back pressure from the cylinders was reduced. However, this arrangement was not convincing due to the flue clogging with soot and ash and quickly disappeared from the scene.

The locomotives had an outside frame, whereby the power was transmitted to the driving axle via Hall cranks. In the second series, the leading axles were in a bogie, but in the rest they were stored in the frame again.

In addition to the two pre-series models, three other series of eight locomotives each were produced. Due to the increasing train weights, the first examples were retired in 1875. The others were first pushed into service with normal passenger trains and later only used for shunting. Today only the “Phoenix” locomotive still exists. It was refurbished in 1960 and has been in the Nuremberg Transport Museum ever since.