A steam locomotive uses a steam engine as its main source of power. The most popular form of steam locomotive includes a boiler to produce the steam used by the engine. The water in the boiler is heated by charring flammable substances such as wood, coal, or oil to produce steam.
The engine’s steam drives pistons called “driving wheels,” which are adjacent to the main wheels. Both water and fuel, water supplies are transported with the locomotive, either in bunkers and tanks or on the locomotive. This configuration is called a “tank locomotive”. Richard Trevithick created the first full-scale operating railroad steam locomotive in 1802.
Modern diesel and electric locomotives are more expensive, and these locomotives require a much smaller crew to operate and maintain. UK railroad figures demonstrate the fact that the fuel costs for a steam locomotive are more than double that of a comparable diesel locomotive; the daily mileage they can run is also less.
As the 20th century drew to a close, any steam locomotive still running on steam power was considered a primordial railroad.