Class 18.4 Steam Locomotive The first unit left the builder in July of 1908. By 1911, Maffei delivered another 16 almost structurally identical units in three production runs. In a departure from the first locomotives, 18 units (Series d and e, Maffei 1912/1913, road numbers 3624-3641) were equipped with driving wheels with a diameter of 2,000 mm / 78-3/4". This caused the boiler on these units to be higher. The "High Stepper" S 3/6 placed into service in 1912/13 developed into the masterpiece of Bavarian express locomotives. They proved to be marvelous long-distance runners and were virtually predestined for fast trains especially. They thus immediately hauled without stopping the D 57/58 between Munich and Würzburg (277 km / 173 miles in 3 hours 20 minutes) as well as the D 79/80 between Munich and Nürnberg (199 km / 124 miles in 2 hours 15 minutes). Unfortunately, World War I ended these marvelous performances a little later. On the DRG the remaining units with small wheels were given the road numbers 18 401-434, 18 461-478, and 18 479-548, the "High Steppers" the road numbers 18 441-458. With a few short-lived exceptions, the latter remained true to their Bavarian homeland. Even though all of the "High Steppers" survived World War II, hardly a unit experienced the German Railroad period. Almost all were retired in the first postwar years. One exception was road number 18 451, for starting in February of 1950 it was made available to the Locomotive Research Institute in Göttingen. There, it did a series of excellent runs. Among them, the long-distance run of May 2, 1951 still occupies a remarkable position. The running times of the newly introduced Ft 56 express powered railcar were specified for the new bi-level train to be hauled from Hamburg to Munich. Actually, road number 18 451 was able to maintain the running times of the Ft and in part even undercut them somewhat. The absolute most remarkable thing on this run was covering an 820 km / 513 mile long route in the long-distance run with a locomotive that had just reached 40 years old and without dumping cinders in between. Actually, the fire was still so good upon arrival in Munich that road number 18 451 could have done another 100 to 200 km / 63 to 125 miles. Starting in April of 1952, the research institute was then able to do without the locomotive and it was put into storage. By 1958, it was immaculately refurbished at the repair facility in Ingolstadt, put back to its original condition, and transferred to the German National Museum in Munich as a donation, where it currently occupies a place of honor as the only surviving "High Stepper".