Deutsche Bundesbahn
In the 1950s a large part of the Deutsche Bundesbahn's vehicle fleet underwent modernisation. As a result, 30 Class 18.5 engines were rebuilt by the firms of Krauss-Maffei and Henschel. These were the series l to o locomotives built for the Reichsbahn between 1927 and 1930.
These units were given a newly developed replacement boiler with combustion chamber at the Ingolstadt and Munich-Freimann repair sheds by the Minden engine shed and Krauss-Maffei. In addition the locomotives were given a new driver's cab and multiple-valve superheated steam regulator. Further planned modifications, such as new cylinder blocks, were not carried out.
The rebuilt locomotives placed in service between 1953 and 1957 were given the new operating numbers 18 601–630 and were used in express train services, where they almost matched the Class 01 in their performance. They were stationed in the engine sheds of Darmstadt, Hof, Regensburg, Nuremberg Main, Lindau and Ulm.
Although the modernised locomotives were very powerful and the most economical steam engines in the Deutsche Bundesbahn fleet, they were all withdrawn from service between 1961 and 1965. The reason was that, during the rebuild the pump mounting had been directly welded to the boiler which had led to the formation of cracks. The boiler pressure had therefore to be reduced from 16 to 14 bar, which meant the locomotives lost a considerable amount of power.
The last locomotives (18 622 and 18 630) were taken out of service in 1965 in Lindau and scrapped in 1966. By contrast number 18 612 is preserved in the German Steam Locomotive Museum (Deutsches Dampflokomotiv-Museum) where it can be viewed.
The unmodified S 3/6 engines were all withdrawn by 1962, apart from 18 505. This was still in service until 1967 with the LVA Minden and was not paid off until 1969 as number 018 505. It is preserved in the Neustadt/Weinstraße Railway Museum (Eisenbahnmuseum Neustadt/Weinstraße).
Several locomotives were rebuilt into heating locomotives (Heizlokomotive). Number 18 602, stationed in Saarbrücken was mustered out in 1983. Only the wheelsets remain and may be seen in the main railway station. Before its refurbishment, 18 612 was last used as a heating engine.
Read more about this topic: Bavarian S 3/6