Where does the steam go?

[selector]

Thanks very much, up829.

[Anonymous]

There are some pics of the interior of UP 428's smokebox at the link below. The steam delivery pipes are a little hard to make out, but are the 2 big ones that run from near the top and curve down to the sides. The exhuast nozzle is also visible at the bottom. The superheater is just a series of small tubes that loop back through the flues near the top that gives the steam an extra dose of heat. 428 doesn't have a front-end throttle and it's superheater is relatively small compared to 844. The Trains issue covering 844's rebuilding is November 2005 and includes a really good illustration showing what's inside a boiler.

A feedwater heater uses steam to pre-heat the water coming from the tender. Some use steam from the auxiliary steam turret near the cab, others from the steam dome, and some use exhaust steam. Between Elesco and Worthington, there were many different types used on various locos over the years. Auxiliary steam also runs the air pumps, generator, etc.

http://www.irm.org/steamdept/restoration/index.html#428

[selector]

Well, if I understand them, there are two opposing answers here, so I guess my question was reasonably to ask. In any event, I thank you both for them, and hope that others will contribute so that I can get a handle on the truth. It always seemed evident, to me, that the diagonal pipes were inlets for the spindle valves, and that the exhaust went horizontally toward a blast pipe (is that correct?) and up through the stack as an aid to combustion draft. I have never seen what the saddle looks like inside, so it is a mystery to me. Also confusing is exactly how the super heater works as far as routing of steam is concerned. Add the feedwater heater and you can appreciate that a neophyte begins to wonder where all the plumbing fits, and how much maintenance it must need over time given the conditions.

[BigJim]

QUOTE: Exhaust. Check it out and you'll see that it (generally) lines up w/ the stack.

QUOTE: it then splits into 2 pipes inside the smokebox which exit diagonally downward toward the top of the cylinders, where the valves direct it into the cylinders. These pipes are plainly visible on many locos. The exhaust runs through the saddle to an exhaust nozzle directly under, but not attached to the stack.

And the winner is...up829

[Anonymous]

From the steam dome, the steam goes through a dry pipe which runs along the inside top of the boiler to the smokebox. In newer locos, it goes into the superheater header and if equiped the front end throttle. In either case, it then splits into 2 pipes inside the smokebox which exit diagonally downward toward the top of the cylinders, where the valves direct it into the cylinders. These pipes are plainly visible on many locos. The exhaust runs through the saddle to an exhaust nozzle directly under, but not attached to the stack. The upward force of the exhaust creates a draft which pulls hot air through the boiler, which creates steam and keeps the fire burning, etc.

A recent issue of Trains covering 844's rebuilding had an excellent diagram showing all the internal flues, crown sheet, throat sheet, dry pipe, etc.

[jimrice4449]

On second thought, while brevity may be the soul of wit, that answer could be confusing if you assume the steam goes from the valve through the exterior pipe and directly to the stack. There's actually a space between the exterior exhaust pipes in the smokebox and the stack. At the end of the pipes there's a nozzle that is aimed out the stack. W/ each exhaust the steam forces air that had been between the nozzle and the stack out the stack ahead of the exhausting steam, which creates a partial vacuum in the smokebox. The air that rushes in from the firebox to fill the vacuum aids in the cumbustion of the fuel in the firebox. When the engine isn't working an artifcial draft is created by a blower to aid cumbustion

[jimrice4449]

Exhaust. Check it out and you'll see that it (generally) lines up w/ the stack.

[selector]

I know that steam accumulates in the steam dome, and then passes through the throttle valve.....and is routed how from there? Pipes forward to the cylinder cradle, or whatever the y-shaped cast body is called behind the pilot?

The sloped thick pipes between the outer front boiler jacket and the valve cylinder...is that inlet or exhaust?

Help me out here.