Freight Locomotive with Tub-Style Tender.

What was the special feature of this steam locomotive innovation from Era III? It was a new method from the two Italian engineers Franco und Crosti whereby the hot exhaust gases expelled from the smoke stack were used to preheat the boiler water. According to this principle that had been successfully used in Italy since 1938, the coal consumption for steam locomotives can clearly be reduced. Coal was a sought after commodity and therefore relatively expensive in the period after the war and during the rebuilding of Germany. So, in 1950 the German Federal Railroad adopted this method and had Henschel convert two new class 52 locomotives with Franco-Crosti exhaust gas preheaters. They were designated as the class 42.90 due to the increase in weight. A striking feature of these locomotives was the two main flat smoke stacks the rise up on both sides of the boiler in order not to block the engineer's view. They lend the Franco-Crosti units their typical look. In 1959/60 both of these locomotives were retired from service.