German Reichsbahn class 50³⁵

To resolve the problems with the boiler alloy St 47 K-Mo that got brittle over time, the Reichsbahn had to fit its class 50 locomotives with new boilers. So they designed a new boiler based on that of the classes 23¹⁰ and 50⁴⁰ and fitted it to 208 locomotives of the class 50 between 1957 and 1962. The rebuilt locomotives were called class 50³⁵ and the same boiler was later also use on other Reko classes.

Many locomotives were also fitted with a Giesl ejector. Between 1966 and 1971, 72 were converted to oil firing and called class 50⁵⁰. They were not only used for freight traffic, but also on commuter trains. The last steam-hauled standard-gauge passenger train in the GDR was hauled by 50 3559 in 1988. One year later, the last 50³⁵ and 50⁵⁰ were retired from regular service. Today, a two-digit number is being preserved.