Steam Engines - Keeping the fire hot

[nicknoyes]

I understand the theory of maintaining a hot fire in a steam engine while it is underway by exhausting the steam cylinders into the smoke box. The chew chew sound coming from the alternating exhausts from the left then the right cylinders.

Assuming this is correct, how is the draft maintained when the engine stops temporarily? I have heard stopped locomotives make the chew chew sound even though not a wheel turns and no one is in the cab. This is obviously air pressure which is probably maintaining the fire but what turns on the air?

Nick

[Anonymous]

QUOTE: Originally posted by nicknoyes

I understand the theory of maintaining a hot fire in a steam engine while it is underway by exhausting the steam cylinders into the smoke box. The chew chew sound coming from the alternating exhausts from the left then the right cylinders.

Assuming this is correct, how is the draft maintained when the engine stops temporarily? I have heard stopped locomotives make the chew chew sound even though not a wheel turns and no one is in the cab. This is obviously air pressure which is probably maintaining the fire but what turns on the air?

Nick

I think I can probably answer this question; once upon a time in previous life I used to fire two oil-burning Baldwins. The draft can be maintained via the blower which vary in design but generally is a ring with small holes designed to fit around the nozzle. Like a garden nozzle; it slightly compresses the steam coming out of the steam chests and directs it up and through the petticoat pipes and the stack on top of the smokebox. The fireman will open a valve on the manifold on the left side of the cab...which in turn allows steam into the blower ring...the steam escaping from up through the small holes in the blower ring creates a draft that keeps the fire going.

As for the chew-chew sound while a steam loco is stationary, what you are probably hearing is the cross-compound air pump that provides air to the main reservoir and the brake system. Steam enters the high pressure cylinder, then the low-pressure cylinder and then the exhaust is piped into the smokebox...which like the blower, creates a small draft. Sometime though, when you're stopped and not going anywhere any time soon, you don't really want a draft on the fire. So you close what is called the damper (where air is pulled up into the firebox) and cut the blower and the oil back to almost nil. When a highball is imminent, you open the blower and crank up the blower and the oil...and so on. I hope this answered your questions! :)

[selector]

Thanks for this enlightening answer, Kid! So, for example, when my Hudson expresses a "lubb, lubb, lubb" sound, is that not also an air pump? It is the same as the doubled "tshh-tshh..............tshh-tshh......?

Another question, because it has been eons since I stood trackside near a running loco, but the faint clink-clanking sound, is that the drivers or the eccentric lever....what?

(this is a weird posting, but I gotta ask!)

[Anonymous]

When you hear the "Chlank... chlank.. Chlank..." with a definate metallic sound that is the noise from very heavy metal being pistoned back and forth in the compressor to create air pressure for the brakes.

Some engines go Pant, phant, pant, Phant.... bigger engines Chlank... chlank.. Chlank...

I venture the Hiss you hear is the air release or blow down not sure yet which. My BLI's occasionally create a racket when everything is operating at once.

You would want that fire almost white hot. if it is a dull color and not much pressure on the gauge the engineer will probably not have much steam (power) to work with on the impending hill.

Occasionally my BLI's issue a very loud "C-Clank!" that is the firedoor being slammed shut. It sounds just like a large wrench dropped onto the deck.