Q:Information:  - A steam locomotive is a railway locomotive that produces its pulling power through a steam engine. These locomotives are fueled by burning combustible materialusually coal/coke, wood, or oilto produce steam in a boiler. The steam moves reciprocating pistons which are mechanically connected to the locomotive's main wheels (drivers). Both fuel and water supplies are carried with the locomotive, either on the locomotive itself or in wagons (tenders) pulled behind. The first steam locomotive, made by Richard Trevithick, first operated on 21 February 1804, three years after the road locomotive he made in 1801. The first practical steam locomotive was built in 1812-13 by John Blenkinsop.  - The Milwaukee Road 's class F7 comprised six ( # 100 -- # 105 ) high - speed , streamlined 4 - 6 - 4 `` Baltic '' or `` Hudson '' type steam locomotives built by Alco in 1937 -- 38 to haul the Milwaukee 's Hiawatha express passenger trains . Following on from the success of the road 's class A 4 - 4 - 2s , the F7s allowed the road to haul heavier trains on the popular Chicago -- Twin Cities routes . The F7s are major contenders for the fastest steam locomotives ever built , as they ran at over 100 miles per hour ( 160 km / h ) daily . One run in January 1941 recorded by a reporter for Trains magazine saw 110 miles per hour ( 180 km / h ) 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 125 mph ( 201 km / h ) and sustained an average 120 mph ( 190 km / h ) for 4.5 miles ( 7.2 km ) . However , the British locomotive LNER Class A4 4468 Mallard is officially accepted to be the world 's fastest , with a run recorded at 125.88 mph ( 202.58 km / h ) in 1938 . The Milwaukee F7s are accepted as the fastest steam locomotives by a different measure -- scheduled speed between stations . In 1939 , shortly after they were introduced into passenger service , the Twin Cities Hiawatha schedule was modified such that the engines would need to run the 78.3 mi ( 126.0 km ) between Portage and Sparta , Wisconsin in 58 minutes -- a start - to - stop average of 81 mph ( 130 km / h ) . First - built # 100 was also the first withdrawn from service , on November 10 , 1949 ; last - built # 105 was the final one in service , withdrawn August 10 , 1951 . All were scrapped .  - On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled together with side rods (also known as coupling rods); normally one pair is directly driven by the main rod (or connecting rod) which is connected to the end of the piston rod; power is transmitted to the others through the side rods.  - Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of four leading wheels, six powered and coupled driving wheels and four trailing wheels. In France, where the type was first used, it is known as the Baltic, while it became known as the Hudson in most of North America.    Given the information above, choose from the list below the object entity that exhibits the relation 'powerplant' with the subject 'milwaukee road class f7'.  Choices: - steam engine  - steam turbine
A:
steam engine