Re: Locomotive Steam Characteristics

From my limited experience with firing steam, as well as discussing this very subject, it seems to be a lot of "little things" that add up to the big picture of how the locomotive fires, steams, runs, etc. A very large part of how an engine steams, which is to say how well it makes steam (how easy/difficult it is for the fireman to keep a steady steam pressure or build pressure when needed), is the design, positioning, and use of the firebox. If a firebox is long and narrow, fat and wide, etc. has a great deal to do with how the capability of an engine to produce the steam it will use when working. Other factors that come into play include the smaller adjustments to an engine, such as how much draft (air fed to the fire through the bottom of the firebox), smokebox adjustments such as the petticoat pipe, fuel quality, and the fireman's practices. Sometimes everything can be honed and adjusted to where the engine will perform beautifully, and then other times the engine will steam poorly, seemingly regardless of what is adjusted or changed. That is the beauty/curse and utterly intriging mystery about steam locomotives.
There are many others here that have a hell of a lot more experience than I. They can give you a much better idea than I can on this.
~My 2 cents
Shane