Since the locomotives from the early days were no longer powerful enough, newer ones with an 2-4-0 wheel arrangement were procured from Maffei in Munich. 20 of these were delivered from 1873 and were based on the Bavarian locomotives. It is noteworthy that from 1888 all of them were rebuilt to tank locomotives with an 2-4-2T wheel arrangement and remained in use as such.
In order to increase the output, following the trend of the time, the grate area was enlarged. A further increase in power was achieved through a higher boiler pressure, which had become possible due to new materials and production techniques. The locomotives had an outside frame and outside cylinders, but internal Stephenson-type valve gear. Braking, as was usual at the time, was done with mechanical transmission only to the wheels of the locomotive.
After a few years of operation, it became apparent that the adhesive weight was too low and the running characteristics with the long rear overhang were no longer up to date. Therefore, the locomotives were equipped with a trailing axle and turned into tank locomotives, while most parts remained the same. Because the weight of the water was now acting on the driving axles, the adhesive weight increased. In addition, more powerful boilers of the Baden type were used later and the brakes were replaced with a modern air brake system of the Westinghouse type.
The rebuild was completed on all locomotives in 1892 and extended their operating life beyond what the original tender locomotives would have achieved. The withdrawals began in 1901, the last locomotive was taken out of service in 1910.
