A Steam engine is an engine which uses steam from boiling water to make it go. It can change the energy, which is in hot steam, into movement, which can then be used to work a factory or move a railway train or boat.
The steam engine was invented by James Watt around 1776 and they were very important during the industrial revolution where they replaced horses, windmills and watermills to work machines. The first steam engines were piston engines. The steam pressure pushed on a piston which made it move along a cylinder and so they had a reciprocal (back-and-forth) motion. This could move a pump directly or work a crank to turn a wheel and work a machine.
The steam to power a steam engine is made in a boiler. Water in the boiler is heated to make steam. The steam coming out of the boiler applies the force on a piston or turbine blade. Movement of the piston or the turbine blade is then used to turn wheels or drive other machinery. To boil the water in the boiler, several types of fuels may be used. It may be wood, coal, or oil.
Today almost all steam engines are turbines which have no pistons but spin like a windmill pushed by jets of steam. These work much better than the original kinds of piston steam engines. They are used in power plants to operate generators which make electricity. Some ships, like large warships, are also powered by steam turbines.
A steam engine in the Deutsches Museum in Munich
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