The DB Class 41 with the Older Design Boiler
The class 41 fast freight locomotive was part of the late developments in the German State Railroad's (DRG) standardized locomotive program. Different components were identical with the classes 06 and 45 developed at about the same time. A special design feature of the class 41 was also common to these other locomotives: Their wheel load could be set either at 18 or 20 metric tons in order to ensure wider use. The frame was a new development but the boiler was the same as on the class 03. The St47K had to be used as the material for the boiler due to the higher boiler pressure of 20 atmospheres or 290 pounds pressure per square inch. The Berlin Machinery Builder, Inc., formerly Louis Schwartzkopff, delivered the two sample units, road numbers 41 001 and 002, in 1936. These units were tested extensively. From 1938 on they were followed by 364 regular production locomotives that were improved somewhat and that were delivered by almost all of the German locomotive builders by 1941. Due to World War II, the DRG canceled another 70 locomotives already ordered and replaced them with the transition war designs and war design locomotives. As with other locomotives, the St47K boiler on the class 41 exhibited after a few years traces of metal fatigue since this boiler material was not resistant to aging and became susceptible to breakage at weld points. For that reason, the boiler pressure was initially reduced to 16 atmospheres or 232 pounds of pressure per square inch starting in the fall of 1941. Furthermore, the DRG purchased a total of 40 replacement boilers in 1943/44 that were made of the much more durable St34 boiler material.
After World War II, there were 220 locomotives on the DB's roster and 124 on the GDR's German State Railroad (DR) roster. Since both government railroads could not do without the class 41, numerous units were equipped with new boilers. On the DB 102 units were rebuilt and equipped with welded, high-performance boiler with a combustion chamber. Moreover, 40 units were converted to oil firing. On the units not rebuilt boiler damage could be kept within limits by not exceeding the lowered boiler pressure. Improved welding techniques in the meantime took care of the problems for the most part. The class 41 units with the older design boiler were retired for the most part in the Sixties and only a few units lasted until the computer renumbering system change to the class 041 in 1968. Road numbers 041 253 and 334 were stored at the maintenance facility at Cologne-Eifeltor in September of 1970 and were retired on November 27, 1970.