Syd Schofield

Editors note: Welcome to the fifth article of a series on narrow gauge by Syd Schofield. The previous article is available by clicking here, or by filtering with the category “Narrow Gauge”. Syd welcomes discussions and feedback, which can be made by clicking on the comment link at the bottom of the post.

The common sources of energy for heat engines have been wood, coal, and petroleum products. These carbon based fuels combine with oxygen at a sufficient temperature for a continuous release of heat. In the railroading scheme of things this heat is then converted to mechanical energy to provide locomotion. Since the system for this activity is self-contained, adequate carriage must be provided for the conversion mechanism and the fuel for a reasonable distance of travel. Provisions must be made along the route for replenishment.

The external combustion engines typically used also need a working substance in addition to the fuel consumed in these total-loss systems. In the steam engine we use water for the working substance and wood, coal, or oil for the fuels. Air is in abundance (except for in long tunnels with previous traffic and inadequate ventilation) as the oxygen supply. The starting temperature for chemical conversion (ignition) has been taken care of by the fireman before expected use of the locomotive in order to bring up the system to operating condition. As with the sustaining process of the locomotive during operation, starting the system can be complicated.

The types of fuel to be used in the steam engine must be determined before the manufacture. Later conversions are sometimes possible with considerable effort but not “on the fly” during daily operation. In the carriage of fuel and water certain planning must take place for usage and replenishing stations. The abundance of wood made for an easy choice in the early days or railroading. Coal took a little more effort in procurement but has twice the heat energy of wood, allowing a smaller carriage for a given distance. Oil became available and has three times the heat content of wood with a likewise reduction in carriage provisions. The water is consumed at a much greater rate and is typically serviced by more closely spaced stations, again depending on availability.

Railroads make revenue by hauling freight and passengers, not fuel and water, so planning for the fuel and water servicing is an important part of the business plan. Given the hand-me-down shoestring operation of many narrow gauge and remote operation railroads, this can give an interesting operational balancing act for the railroad. Typically modeling won’t have the luxury of space for distances to be factored into the operation, but then it’s a pretend world anyway and we can simulate conditions.