Steam Locomotive

trains · steam power · machines

Fire heats water. Steam locomotives burn coal or wood to heat water in a boiler until it turns to steam. That steam expands so much (1,600 to 1,700 times bigger!) that it pushes pistons connected to the wheels.

Steam does the work. As steam pushes the pistons back and forth, the pistons turn the locomotive's wheels. This is the same principle as a steam engine, but the whole engine sits on rails and moves itself.

Self-propelled machine. Unlike earlier trains pulled by horses, steam locomotives create their own power from burning fuel. They can pull heavy cars of freight or passengers across long distances without getting tired.

No electricity needed. Steam locomotives work without electricity or cables. All they need is fuel and water, which made them perfect for building railroads across countries before modern engines were invented.