Bavarian BB I and Palatinate Railways G 4^II

The BB I was a single Mallet locomotive with a 0-4-4-0 wheel arrangement, which was primarily used to push freight trains on the steep ramps in Franconia. The locomotive built by Maffei was originally intended for the Swedish-Norwegian railways, but was then taken over by the Bavarian State Railways. The Pfalzbahn also procured two identical locomotives in 1896 and designated them as class G 4^II.

In contrast to the BB II, which was later built in series, it was a tender locomotive, and it was also much heavier with an axle load of 14 tonnes. The rest of the structural design was similar, with vertical connecting pipes from the steam dome to the high-pressure cylinders in the middle and the low-pressure cylinders in the front. Like other four-axle Mallet locomotives, the machine was notable for its rough running and strong tendency to slip, which is why no more were procured. The same observations were also made at the Pfalzbahn with the two identical machines, whereupon these were only used in part to test new braking systems.

Both operators decided to use eight-coupled locomotives again in the future, as these did not have the weaknesses of the Mallets, despite the somewhat poorer curve running properties. The Reichsbahn number 55 7101 was reserved for a single remaining BB I, but this was no longer taken over due to the decommissioning in 1923. The Palatinate machine, which was still in use up to this point, suffered the same fate.