The Class 50, arguably the most significant DB steam locomotive of the 1950s and 60s with many design variants, had proven itself on almost all types of trains on main and secondary lines. More than 60 essential variants ensured that hardly any two Class 50 locomotives looked completely identical to each other. Built from 1939 in around 3,100 units, these 1'E freight locomotives were considered robust, powerful, easy to maintain, and extremely reliable. After 1945, over 2,000 locomotives remained with the Deutsche Bundesbahn. The machines achieved a top speed of 80 km/h, delivered about 1,200 kW of power, and had an axle load of 15 tons. When the EDV class numbering system was introduced in 1968, there were still 1,452 machines in the DB's inventory. Since the order number could only be three digits long, the designations 051, 052, and 053 were introduced in addition to the class number 050.