MÁV Class 601

The MÁV class 601 (nicknamed as "The Giant" or "Big boy" ) is a class of Hungarian four cylinder Mallet -type locomotives, which was designed to haul long and very heavy cargo on very steep railway tracks. With their 22.5 meter length and 2200 KW power, they were the largest and most powerful steam locomotives which have ever built before (and during) the First World War in Europe.

Based on the good operating experience with the series 651 more powerful locomotives arose at the MÁVAG in Budapest from 1914 on, which were especially provided for the line from Karlstadt (today: Karlovac, Croatia) to Fiume (today: Rijeka). By utilisation of the permitted axial load of 16,5t a locomotive was developed, which alone could move freighttrains uphill even on the steep line in the croatian karst without a banking engine.