There are four parts needed to make a steam engine work and here they are.
1. A fire where the coal burns.
2. A boiler full of water that the fire heats up to make steam.
3. A cylinder and piston, a bit like a bicycle pump but much bigger. Steam from the boiler is piped into the cylinder causing the piston to move first one way then the other. This in & out movement (which is known as reciprocating) is used to drive……….
4. A machine attached to the piston. That could be anything from a water pump to a factory machine, or even a giant steam locomotive running up and down a rail track………..or Titanic!