This image here is a old train.
Trains were made by a man called Thomas Newcomen in 1705.
You can see in this diagram that the exhaust steam simply vents out into the air. This fact explains two things about steam locomotives:
- It explains why they have to take on water at the station -- the water is constantly being lost through the steam exhaust.
- It explains where the "choo-choo" sound comes from. When the valve opens the cylinder to release its steam exhaust, the steam escapes under a great deal of pressure and makes a "choo!" sound as it exits. When the train is first starting, the piston is moving very slowly, but then as the train starts rolling the piston gains speed. The effect of this is the "Choo..... choo.... choo... choo choo-choo-choo" that we hear when it starts moving.
Thanks Ashley - yes Thomas Newcomen invented the steam engine, however it was someone else who combined the engine with transport to make a train. The steam engine resulted in the invention of lots of machines that changed the way people lived.
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