The Steam Locomotive

The Steam Locomotive. The strength of the steam engine is its ability to convert raw heat into mechanical work. The first Steam Locomotive Engine was designed by George Stephenson in 1814 at the age of 20. The diagram shows major components of a piston steam engine, which would be typical in a steam locomotive., Captions , Upper Right: Black Hills Central #110, built in 1928, Lower Right: , Steam Engine Operation , The engine shown is a double-acting steam engine because the valve allows high-pressure steam to act alternately on both faces of the piston. , You can see that the slide valve is in charge of letting the high-pressure steam into either side of the cylinder. The control rod for the valve is usually booked into a linkage attached to the cross-hegd, so that the motion of the cross-head slides the valve as well. (On a steam locomotive, this linkage also allows the engineer to put the train into reverse.), The exhaust steam simply vents out into the atmosphere. 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. There is one revolution of the driving wheels for every four exhausts. The effect of this is the "Choo... choo.... choo... choo choo choo-choo" that we hear when it starts moving. , . On a steam locomotive, the cross-head links to a main rod, and from there to side rods that drive the locomotive's wheels.