Trains that are powered by coal, specifically steam locomotives, utilize the energy from burning coal to produce steam, which powers the locomotive's engine and propels the train forward. While it may seem counterintuitive for a heavy train to move using coal as fuel, the key lies in the conversion of energy.
Here's a simplified explanation of how steam locomotives work:
Coal is loaded into a firebox located within the locomotive's boiler. The firebox contains a grate where the coal is burned.
As the coal burns, it generates intense heat, which in turn heats the water surrounding the firebox and boiler.
The heated water turns into steam under high pressure. The steam is then directed into a series of pipes and valves, ultimately reaching the cylinders of the locomotive's engine.
Inside the cylinders, the high-pressure steam pushes against a piston, causing it to move back and forth. The movement of the piston is connected to the driving wheels of the locomotive.
The reciprocating motion of the piston is converted into rotary motion through a connecting rod and crank mechanism. This rotary motion is then transferred to the driving wheels, causing them to turn.
The turning of the driving wheels propels the train forward.
The reason steam locomotives were able to move heavy trains is because the energy released from burning coal and generating steam is concentrated and powerful. This energy is harnessed to create high-pressure steam, which is then utilized to drive the locomotive's engine. The immense torque produced by the steam engine allows the locomotive to overcome the weight and inertia of the train and achieve forward motion.
It's worth noting that modern trains, especially those used for transportation and freight, have largely transitioned away from steam power and now rely on diesel or electric engines, which offer greater efficiency, power, and environmental benefits.