A few decades ago, only steam locomotives pulled trains on the railways. At its core, a steam locomotive is a self-propelled machine designed to move cars and equipped with a steam power plant. It is the oldest type of locomotive that dominated railways around the world in the 19th century. How does a steam locomotive work?
General arrangement of a steam locomotive
Over the long history of the development of railway self-propelled installations, the design and dimensions of steam locomotives have changed more than once. Individual units and assemblies were improved, the power of the steam power plant was increased. But in general, the internal structure of the locomotive at all times remained the same. In libraries today you can find detailed descriptions of the principles of operation of machines driven by steam ("How the steam locomotive is arranged and works", VA Drobinsky, 1955).
Traditionally, a steam locomotive includes a steam boiler, a steam engine, a crew, and sometimes a tender. All these parts are very closely related to each other and individually mean practically nothing. Compressed steam is generated in the boiler. The machine is a consumer of steam and converts its thermal energy into mechanical energy, which, in turn, drives the wheels of the locomotive.
The crew converts the rotation of the wheels into a translational movement of the entire structure, and also transfers the tractive effort to the tender and the entire train.
What's inside the locomotive?
The steam boiler is very simple in structure. It has a firebox where fuel is burned. This produces hot gases. The water is heated in the tank, which contributes to the production of compressed steam. There is also a chamber with a pipe through which the combustion products are removed from the combustion chamber.
The steam engine is designed for a single purpose: to convert the energy of the superheated steam generated in the boiler into another type of energy with maximum benefit. After all, only mechanical energy is capable of ensuring the rotation of the wheels of a steam locomotive. The main elements of a steam engine are cylinders. Typically, each steam locomotive has a pair of cylinders that are placed at the front of the locomotive frame.
The steam engine works on the twin-action principle. During its operation, steam is admitted alternately from both sides of the piston.
Steam does not enter the cylinders immediately. First, it passes through the spool boxes. Spools are devices that distribute steam. Through them, fresh steam enters the cylinder, and the spent steam is discharged outside. The spools move in exact accordance with the movement of the pistons, which is achieved by means of a special steam distribution mechanism.
And finally, the crew. It performs a supporting function: it houses a steam boiler and a steam engine. This part of the internal structure of the locomotive, when interacting with the rail track, transforms the mechanical energy of the steam engine into the energy of the locomotive's translational motion. In other words, the crew is vital to the movement of the locomotive on the rails.
