The Class 18.5 Express Steam Locomotive In the early part of 1907, Maffei was given the contract to build a Pacific compound locomotive for the Bavarian State Railroad. Based on the Baden "IV f" built by the same builder, Maffei developed the Bavarian S 3/6, which was fated to fascinate generations of railroad fans by virtue of its timelessly elegant appearance that was chiefly characterized by the four-cylinder compound running gear. The first unit left the builder in July of 1908. Another six locomotives followed it in the same year. By 1911, Maffei delivered another 16 mostly identical units in three builder series (a to c). Departing from these first 23 locomotives, 18 units (Series d and e, Maffei 1912/1913) were equipped with driving wheels with 2,000 mm / 78-3/4" diameter instead of 1,870 mm / 73-5/8". This also caused the boiler to sit higher on these units. Starting with Series f (three units, 1913/1914) however, the builder returned to the original driving wheel diameter. By 1918, the Series i closed out this first purchasing period. With the exception of the 18 "High Steppers", the remaining 71 units all had "wind splitter" streamlined cabs. The second purchasing period began in 1923 and did not end until the State Railroad era in 1931. Maffei delivered the Series k with 30 units in 1923/24. The Series l and m followed in 1927/28 (20 units) as well as the Series n with only two units in 1930. The last 18 units of the S 3/6 as the Series o were built by Henschel in 1930/31 under license because Maffei went bankrupt. The locomotives were initially based in Munich, Nürnberg, and Ludwigshafen and they ran in heavy express train service. After World War I, 19 units had to be surrendered as reparations. On the DRG the remaining locomotives with small wheels were given the road numbers 18 401-434, 18 461-478, and 18 479-548. The units with large wheels were given the road numbers 18 441-458. In addition to the great Bavarian maintenance facilities, the locations at Wiesbaden, Darmstadt, Halle/S., and Osnabrück were also home bases for the Bavarian flagship locomotive. The most famous train assignment during the State Railroad era was surely the FFD 101/102 "Rheingold". After World War II, these locomotives migrated for the most part into ordinary passenger service. From 1953 to 1956, 30 units from the last three series were updated by the DB from the ground up. By 1962 the last of their non-modernized siblings were in storage. Only road number 18 505 remained in operation at the BZA Minden as an experimental locomotive until May of 1967. Today it can be admired at the DGEG Railroad Museum in Neustadt/Weinstrasse.