Coal Size

nw-mailing-list at nw-mailing-list at
Wed Mar 1 23:00:31 EST 2006

To the gentleman asking about the size of coal in a tender. As a former
locomotive fireman, the size of coal lumps was of no consequence. They
varied from egg-sized up to nearly the size of a football. Using a Standard
HT Type stoker, a lump of coal falls into the coal trough in the floor of the
tender where it comes into contact with a screw or auger powered by a twin
cylinder steam engine to begin it's 12 to 14 foot journey to the jet plate
located in the firebox just below the butterfly door. As the coal is forced
through the round chute by the auger, it is crushed into smaller pieces much
;like meat going through a meatgrinder. When it reaches the entrance to
the firebox all of it is reduced to about the size of marbles as it falls
on the jet
plate where air pressure blows or distributes these pieces of coal to various
locations in the firebox determined by vertical "wings" on the jet plate. The
fireman determines how strong the pressure is on each section of the jet
with the use of 6 valve handles positioned in a "V" shape just below the
main stoker valve that controls the speed at which the stoker engine
The biggest headache in using a Standard HT Type stoker is wet coal, that
falls on the jet plate as so much mud. This tends to build up a hard crust on
the jet plate which is loosened by a tool on the engine known as a jet pick.
It is curved similar to a fish hook, and the fireman opens the fire door and
pulls the point back toward him to loosen this residue buildup. In the
case of a shovel fired locomotive, a tender full of egg -sized coal is
to fire a locomotive. Again, to answer your question, on a stoker fired
locomotive coal size is of no consequence. Bill Sellers.

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