Milwaukee Road class F7
The F7s are major contenders for the fastest steam locomotives ever built, as they ran at over daily. One run in January 1941 recorded by a reporter for "Trains" magazine saw achieved twice—in the midst of a heavy snowstorm. Baron Gérard Vuillet, a French railroading expert, once recorded a run between Chicago and Milwaukee where the locomotive reached and sustained an average for . However, the British locomotive LNER Class A4 4468 "Mallard" is officially accepted to be the world's fastest, with a run recorded at but authenticated at 126 mph in 1938.
4-8-4
With three cylinders, large diameter coupled wheels, a high boiler pressure and of tractive effort, they were capable of a maximum speed of and could haul a 650 tonne train at . Many parts, such as the boiler, were standardised with that of the DRG Class 45 heavy freight locomotive. The streamlined Class 06, the only German , was the biggest steam locomotive ever built in Germany. The two locomotives were shedded in Frankfurt and were placed in service on the line to Erfurt. No. 06.002 was bombed and destroyed during the hostilities and no. 06.001 survived until 1951, when it was retired and scrapped.