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Atticus-W — old sketch find number 1
Published: 2009-10-02 01:35:45 +0000 UTC; Views: 294; Favourites: 8; Downloads: 2
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I was perusing some deep, dark, and abandoned files on my compy when I came across a few interesting tidbits! Turns out I’d scanned some “ancient” drawings a couple summers ago and entirely forgotten about them since. Looking back, I now recall only having scanned them after looking through some of my old (even then!) high school notebooks and finding some doodles worth saving. XDMy notes indicate that this little number dates back to sometime between 2004 and 2006. I actually quite like this one— it’s got some kinda cool return-flue boiler with a very long “firebox.” Very high-tech steampunky.
An enclosed crankcase and Pennsy-style snifter valves apparently round out the deal.
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Comments: 21
Number 1: I didn't draw any side rods.
Number 2: What you probably think is side rods is actually the drive rod crankcase. That's right... ENCLOSED drive rods! XD
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OH DARN YOU
HOW IS THIS EIN DON'T E-- (Head Explodes)
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TWO PASS BOILAH WITH PENNSY SNIFTERS=WIN
those snifters had better intake from the superheater or I must name you the king of cylinder condensation and piston-shattering water-slugs!
XXDDDDDDDDDDDDDDDDDDDDDD
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I kinda assumed they'd intake from the atmosphere, but really, darned if I know. XD
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oh some do that, but the incoming cold air causes cylinder condensation and wreaks havoc with having to warm the engine up again.....cold cylinders after a long coast while the engine is moving at mainline speed? OUCH.
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Hmm... interesting point. :\
Nevertheless, it seems that every snifter valve I've ever seen DOES intake from the outside air... certainly the Pennsy style seems too, with its open grates and all, and I've personally seen an engineer up close adjusting the snifter valves on Strasburg's No. 90 and am fairly confident when I say that those valves drew from the outside air as well... and anyway, wouldn't drawing steam from the superheater (via outside pipe, I presume?) be detrimental to the purpose of shutting the throttle, considering the superheater is as likely as not constantly under pressure? If the superheater WAS under pressure (thanks to a front-end throttle), would the snifter valve admit just a trickle of steam from said header when the cylinder pressure drops? If the superheater was NOT pressurized (owing to a conventional throttle), linking the snifter valves to the superheater would do NOTHING to prevent a cylinder vacuum... you’d just be creating a “ parallel”-type steam circuit, all of which would be under vacuum (or so it seems to me).
You know me... just curious.
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not at all, the superheater would reequalize through the wet end/header drum. the LNER and NER did this ALOT. the problem they ran into was that, on their high performance steamers, the gasses drawn in from the superheater were so hot, that the lubrication inside the cylinder would burn off, casing........badness.
MRTC engines use a heat-exchanger which receives heat from a bypass off the superheater and transfers it into an intake air-manifold which in turn vents into the snifting valves. Not to hot, not the cold, and not too terribly complicated. dont know why nobody tried it before!
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Ay, the snifters might be linked to the wet side of the header, but wouldn't they still end up sucking against a closed throttle valve a bit farther down the main steam pipe?
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nono, the throttle is shut yes, but remember, the cylinders are drawing a vacuum on the exhaust, but making pressure on the intake (superheater) side, so the gasses flow in a circuituous pattern!
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*grabs pencil/paper and draws up a little diagram...*
Funny, I just don't see it. Seems to me a coasting locomotive would draw create a vacuum in the intake side and create pressure (back pressure) on the exhaust side. Otherwise, why would the snifter valves (meant to equalize a vacuum, are they not?) be located in the intake chambers of the cylinder valves?
And besides, how can you create a circuituous flow between cylinders and superheater when gas is being thrown up the stack the whole time?
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OHOHOHO
ohhh I didn't know YOU didn't know! you are right ion all but one respect. moving cylinders, with the valvegear in forward, draw a vacuum (as weird as it sounds) on the EXHAUST side!
yes the snifter valves are to prevent vacuum, but from the exhaust side. if it was on the intake side there would be no need for snifter valves. if the vacuum is let to suck in crap from the blast pipe from the smokebox, it wreaks havoc with the cylinders.
coasting with a superheater intake snifter valve will create a circuituous gasflow, in through the snifter valves towards the vacuum, expelled out the intake side back into the superheater.
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Very wierd indeed. O.o Is this exhaust side vacuum created by the motion of the cylinder valves, as opposed to the pistons??
(Also, the Pennsy-style centered snifter valves seem very ill-placed to dispel any exaust side vacuum...)
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no, the snifters can vent from anywhere in the piston, which prevents the vacuum on the exhaust side. its very hard to explain unless you know the dynamics by heart....lets see
the motion of the piston moves air, and the position of the valvegear valve at the time leads that airflow to suck from the exhaust port and push into the intake port. Placing a snifter valve in either the piston ends and/or the steamchest will stop this from happening
because if it didnt, the heavy would go "AH DIS IS BAD, HOW COULD DIS HAPPEN!"
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"its very hard to explain unless you know the dynamics by heart...."
Right you would seem to be.
(I once made an animated, reversing valve gear model using a geometry computer program... I wish I still had it on me, as it would come in handy right about now. XD)
Thank you VERY much for taking the considerable time to try and enlighten me, I must add. I know I can be a downright nuisance with the questioning!
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NEIN!! I quite enjoy explaining things, especially to a person who really does understand them and can improve them in his mind and then rebuttle them back to me. thats what the steam field is all about!
See with engines with no snifters, when you coast you give it about 3%-10% throttle to keep the vacuum from sucking crud and ash down the exhaust pipe and into the cylinders. It can be abit dicey if you need to slow down going downhill. XDDDDD
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Well, thank you all the same!
And ahahahaha, yes, I imagine.
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