How Do Steam Locomotives Work?


Quick Answer

In a steam locomotive, steam flows through a series of pipes and valves, pushing pistons attached to the wheels of the locomotive and driving it forward. Coal or wood in a firebox heats the water in the boiler, creating the steam. When the steam flows into the pistons, it drives the wheels forward, and then a valve releases the steam and allows the piston to return to its original position for the next push forward.

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Full Answer

Richard Trevithick demonstrated the first steam locomotive in 1804 based on his design for a steam-powered cart. Before the steam engine, heavy loads traveled along rail tracks pulled by teams of horses. The steam engine offered considerably more power and speed, but early designs were prone to pressure vessel failure that could produce a lethal explosion.

In addition to powering the drive wheels of the locomotive, pressurized steam is often used to power other components of the locomotive. One of the earliest additions was a steam whistle, controlled by a valve that could direct excess steam through a fluted pipe to produce a loud, high-pitched warning note to alert pedestrians of the train's presence and arrival.

The steam locomotive became the primary method of transporting goods and passengers across long distances in the 19th century, and the design dominated the railways until the middle of the 20th century. Eventually, diesel and electric engines began to replace steam engines, offering more power and efficiency as well as better reliability.

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