The two Class 06 locomotives built by the firm of Krupp in 1939 were the largest, heaviest and most powerful locomotives in the Deutsche Reichsbahn. They were built for heavy express train duties in hilly terrain. The performance requirement was for the transportation of 650 tons at 120 km/h (75 mph). On ramps of 1:100 it was to still be capable of maintaining 60 km/h (37 mph).
In trials, the vehicles confirmed their remarkable capability and running qualities. However the locomotives tended to derail in tight turnout curves. And, like the Class 45s, the boilers developed cracks, leaky tubes and popped stay bolts, so that the locomotives were unconvincing when hauling measurement vehicles or scheduled trains.
As a result of the war no more were produced. After World War II a locomotive of this size was no longer needed, thus neither the necessary structural modification of the engines was carried out, nor did any follow-on orders result. Both engines were seen as having a faulty design and were retired by the Deutsche Bundesbahn in 1951 in Frankfurt am Main and scrapped, because the DB refused to replace their boilers.
The two locomotives, which had operating numbers 06 001 and 06 002, were equipped with 2'3 T 38 St tenders.
Weisbrod, Manfred; Müller, Hans; Petznik, Wolfgang (1976). Dampflokomotiven deutscher Eisenbahnen, Baureihe 01–39 (EFA 1.1) (in German) (3rd ed.). Düsseldorf: Alba Buchverlag. pp. 63–65. ISBN 3-87094-081-6.