02-18-2009, 12:34 PM
Oh grate! the draft!
"Combustion air", is draft. the flow, for a steam locomotive is through the flues and tubes,and up the stack......but, before it gets to the flues and tubes, it has to be heated by the fire, in the firebox, on the grates, which sit just above the ashpan, and are shaken to get the ash out of the way so that air can pass more easily from the lower edges of the firebox( just below the mud ring), under and up through the grates, the fuel, cause combustion and get heated, then through the flues and tubes where the heat is transferred to the water in the boiler...etc.etc.etc.
When firing up a steam locomotive( cold start), a fan is placed over the stack to start the draft, or, steam from a stationary boiler can be exhausted up through the stack to help draw the air, to get the fire started, and steam up. Once the boiler has sufficient pressure, it can provide its own steam to aid the draft, as needed.
The fireman, controls the draft by using steam through the exhaust pipe, via a valve in the cab.
I think I can be reasonably sure that the grates are the one piece of a steam locomotive that rarely ever get modeled.....unless it is a live steam model.
The space between the grate bars, the sizes of flues and tubes, the stack diameter, and height, all determine the amount of draft, all of which is determined by the type of fuel, and how slowly, or quickly it burns.
The Challengers, that the Clinchfield purchased from the D&RGW, had to be modified from the original double stack, to single stack, and a number of internal boiler changes had to be made so the coal, available to the Clinchfield, could be more efficiently burned.
"Combustion air", is draft. the flow, for a steam locomotive is through the flues and tubes,and up the stack......but, before it gets to the flues and tubes, it has to be heated by the fire, in the firebox, on the grates, which sit just above the ashpan, and are shaken to get the ash out of the way so that air can pass more easily from the lower edges of the firebox( just below the mud ring), under and up through the grates, the fuel, cause combustion and get heated, then through the flues and tubes where the heat is transferred to the water in the boiler...etc.etc.etc.
When firing up a steam locomotive( cold start), a fan is placed over the stack to start the draft, or, steam from a stationary boiler can be exhausted up through the stack to help draw the air, to get the fire started, and steam up. Once the boiler has sufficient pressure, it can provide its own steam to aid the draft, as needed.
The fireman, controls the draft by using steam through the exhaust pipe, via a valve in the cab.
I think I can be reasonably sure that the grates are the one piece of a steam locomotive that rarely ever get modeled.....unless it is a live steam model.
The space between the grate bars, the sizes of flues and tubes, the stack diameter, and height, all determine the amount of draft, all of which is determined by the type of fuel, and how slowly, or quickly it burns.
The Challengers, that the Clinchfield purchased from the D&RGW, had to be modified from the original double stack, to single stack, and a number of internal boiler changes had to be made so the coal, available to the Clinchfield, could be more efficiently burned.
We always learn far more from our own mistakes, than we will ever learn from another's advice.
The greatest place to live life, is on the sharp leading edge of a learning curve.
Lead me not into temptation.....I can find it myself!
The greatest place to live life, is on the sharp leading edge of a learning curve.
Lead me not into temptation.....I can find it myself!