There was a fairly basic difference between fireboxes made for wood
burning and ones designed for coal. When you look at Civil War era
locomotives, one sees that it was common for fireboxes to be no
wider than the frame of the engine. This gave a long narrow firebox
that generally was quite deep to allow layers of wood. Example: the
American Standard 4-4-0.
Fireboxes designed for coal used a wider shallower firebox that
needed to hang behind the drivers or spread above them. This led
to the trailing truck.
There were exceptions, of course. Not to mention design failures
as builders experimented with improvements.
As the railroads evolved, many locomotives were given quicky
conversions from wood to coal but these were generally locomotives
put into secondary service because of poor efficiency compared to
engines built for coal.
One historic example was when the L&N converted a number of locos
along the Gulf Coast where there were few grades. Then a hurricane
blew through Mobile and Baldwin County Alabama. Farmers there lost
most of their crops which often were shipped by L&N. The RR
reconverted several engines back to wood in order to burn fallen
timber and give the farmers a bit of cash until the next year.
Chuck Peck
