|slag or clinker fallen from locomotive
Clinker is formed in the firebox when the firebed melts from its own heat and forms into a gooey mass on top of the firebed
and prevents the free flow of air thru the fire, thus reducing the amout of heat the fireman can get out of the fire.
There are two kinds of clinker - soft clinker and hard clinker.
I don't think that anyone ever came up with a reason for soft clinker. Soft clinker tends to form over the entire fire,
rather than in spots, and forms a brittle crust across the fire. It seems to occur with some coals more than others, and on
some days more than others. Perhaps weather conditions affects its formation. If soft clinker starts to form, if noticed early
can generally be gotten rid of by gently shaking the grates to break it up, and let air thru, then lightly spreading coal
over that. The soft clinker, if broken up adequately, will then work its way to the bottom of the firebed and will drop out
thru the grate. Sometimes, it is necessary to "clean the fire" to get rid of soft clinker. This is done by opening
the firedoor and, with a rake and hoe, pulling as much of the clinker off the top into a pile at the back of the fire, pushing
the hot coals into another pile, then dumping the clinker and ash, then spread out the live coals again and put fresh coal
on top of that. If not caught early enough, though, it will choke off the fire, reducing off heat output to where the only
solution is to dump the entire fire into the ashpan and start over.
Hard clinker tends to form in spots, starting small and slowly growing. These must usually be removed with the rake, hoe,
and poker, by cooling the fire enough to where they harden (they're semiliquid otherwise) and taking them out the firedoor.
Sometimes you can ignore them 'till you get to your next station, then take them out, other times you can break them up with
a poker and hope thay will work their way down thru the fire and drop out the grate before they can grow enough to cause a
bigger problem. Sometimes you just have tot take them out on the road.
Taking out clinkers is very hot, dirty work. Once removed, the red hot glowing mass can be cooled by sprinkling with water,
then tossed over the side. Don't toss them hot - they will set fire to anything they touch.
Hard clinker has several causes. If a large rock or piece of metal gets into the fire, it will start a clinker, but many
are caused by improper firing. Coal should be spread onto the fire in a very thin layer, but if a clump of coal is put all
in one spot, it may start a clinker. Also, stiring the fire with the poker is a great way to raise the temperature of the
fire very quickly by letting in LOTS of oxygen thru the fire, but it's an invitation to the creation of clinker. When coal
is put in, it must go in a thin layer, best done by getting the coal to roll over the top of the fire as it spreads, to keep
breaking up small clinker before it can grow into a problem.
If the ashpan is allowed to become filled, clinker can form in there in huge chunk. These are a real b***h to remove,
as they must be taken out thru the ashpan dump, and if they are too big for that opening they must first be broken up somehow.