We just learned about the Train Whistle.
Another part of a steam engine is the Valve Gear.
This is a gear that is hooked up to the piston that is moving the train along, and lets the engineer open or close it to go faster or slower.
If they open the piston up all the way the train will go faster but will use more fuel.
If they close the piston all the way the train will go slower but will use less fuel.
(from: wikipedia - valve gear)
Kid Facts - Blast from the past: Shaft
