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I am working on an Aristo 2-8-8-2 mallet, converting it to live steam using the running gear from two Aristo Mikados. I am building a custom boiler for this loco. I have to have flexible steam and exhaust lines for the articulation. I havent seen how Aster did this or Accucraft on their cab forward. Any suggestions, photos, on materials, designs, on the lines, or articulation methods would be appriciated. Aristo uses a center pivot point between the second and third drivers on both sets of running gear. This is obviously the easiest way to do it, but the prototype had the rear set rigid to the frame while the front set was the only articulated part. So i can either articulate both sets, the easiest way, or I need to make some working mechanism to articulate the front set only. Any ideas on that would be appriciated also. I will post a thread on the build after I make more progress. I have been taking pictures and plan to insulate the loco simular to the way Aristo did to the mike. Any suggestions out there?

Tim
 

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Asters use the actual piping that the locomotive had. It is articulated with a sliding seal in the pipes, sealed with a spring pushing against O rings. Aster steam pipes are a copper tube, bent to shape. Then covered with electrical tape to make them close to the correct thickness. Then covered with heat shrink tubing, then another layer of electrical tape. In an Accucraft engine, those pipes are just decoration, and the steam moves through a copper pipe underneath the running gear. It is articulated by a silicon hose, which can bend with the front engine.

I would suggest you consider the accucraft way, at least at first. You should be able to do that more easily. I once talked to Lewis about a live steam Mallet, and he was not against it, just that it presented some issues. His first concept was to only power the back engine, with the front free running. He knew that would be easy to do, but was concerned that people would expect more power than one engine can develop.
 

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Tim, please keep us up on your progress. Are you going to continue to use gas fired boiler?? and will it generate enought steam to supply 4 cylinders?? or are you going to build it for meth or coal firing??? It does sound like a great idea. Nick Jr
 

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I maybe wrong but I think the plastic shell of the Mallet would not hold up to the heat. The Mike made by Aristo used a different type of plastic resistant to heat. later RJD
 

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Alternative placement of boiler in another thread on MLS (search lgb and indicate live steam):
Gilbert Bony has successfully converted several plastic electric models to live steam, including an LGB Mikado, LGB Mogul, and an AristoCraft Pacific. I believe he uses Roundhouse cylinders and fabricates his own valve gear from brass. The boiler is mounted in a tank car towed behind the locomotive, which isolates the plastic shell from the worst of the heat. A flexible steam line carries the steam from the boiler through the tender and locomotive to the cylinders.




Flexible steam lines can be designed as indicated in the cab forward thread.
 

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Tim, Regner uses a type of teflon tubing to connect their articulated engines together. They are, as far as I know, always connected through a compound / simple valve. It works well, but it is not a complete requirement, although it does conserve water which is important when the boiler is actually rather small (like my IV K). Take a look at Rod Blakeman's pictures of his IV K and you will see the tubing arrangement and the valve. tubing and valve Dont forget to check out the rest of his pictures for possibly more insite here. I like your project and I have considered it myself but have been distracted by other shiny locos already built. Good luck and keep us posted!
 

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Discussion Starter #7
Thanks all for the input. John, I think you are right to try Accucrafts approach. Charles, I saw the pics you have in your Cab Forward thread. Did you have to modify the swivel pipe, and what was wrong with it that required the mod? I also saw a pic or the saddle/center pivot. Could you send me a pic of how that sits/ rides together when assembled? It appears that the pivot point is behind the fourth set of drivers, but how far forward to put the saddle/center pivot? The exhaust with the silicon tube would be simple enough. I attatched a few photos, first shows the double wall smoke box, using the mike smokebox with the screw in door for the inner. This will be the hottest part, so plenty of room to insulate between the two walls, plus the OD of the 2 and a half inch copper tube forming the boiler and outer smokebox still leaves 1/4 inch between it and the outershell, where it will be insulated as well. I will run some tests on the boiler by firing it before it is in the loco, checking the temp, looking for hot spots using an infared thermometer. Nick, I think gas fired is the only way to go with the plastic shell in mind. RJD, we will have to see just how good the insulation holds up! The last photo shows how Aristo made both the front and rear units pivot. The two shiny screws are the pivot points, allowing both front and rear units to pivot between the second and third drivers. If I can get a good idea on the saddle placement, I will make the rear unit rigid and the front be the only articulated part. Thanks Seadawg for the links. That may be an option as well.

Tim
 

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Discussion Starter #8
I think I might take a trip to the Meuseum of transportation here in St Louis, where I can walk up to a real 4-8-8-4 big boy to get a better understanding of the articulation components


Here is a pic with the Mikado live steam running gear next to the mallet electric unit
 

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What a great project! I'll be interested to see how you close up the gap between the cylinders and the first pair of drivers on the Mikado chassis to match the spacing on the Mallet, I've been contemplating doing that on my Mikado by modifying the frame and shortening the connecting rods and radius rods. I imagine the shorter connecting rods from the Mallet might be usable for your purposes, but I'm not sure if the Mallet's radius rods would be up to the job.


Also, if you're going to St. Louis to check out a full-size articulated, the one you want to look at is the N&W 2156, last of the mighty Y6 class 2-8-8-2's. The Y6 design evolved from the earlier Y3 engines on which the Aristo model is based. You could also take a drive up to the Illinois Railway Museum to see a real Y3.
 

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Thanks Richard, I will check out that loco to, heck I might look at all of them, he he. Have to wait for a warmer day, say 40's or 50's would be nice. On a side note, I emailed Lewis Polk regarding the type of plastic used on the LS Mike verses the type of plastic used on the electric mallet. He said they are the same plastic, the only difference is that the LS Mike has insulation on it, where the electric does not. So if any plastic melts, it would be from lack of proper insulation, not from the type of plastic Aristo used. The Distance between the front and rear sets of running gear are very close together but do not touch. Right now it is set up the way Aristo did the electric version, both sets articulated. Will have to see what mods will be nessessary to make the front the only articulated part, the way I would prefer to do it.

Tim
 

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How did the prototype deal with the reversing components of the valve gear? There would have to be a linkage connecting the reverser stand to the power reverse system on the lead engine unit.
- Andrew
 

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Andrew, not sure about the prototype, I plan to use the electric servo that Aristo already has installed from the Mike.

Manfred, thanks for the link!

Tim
 

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I'm not sure if this is helpful, but coiled copper tube is actually very, very flexible. Regner uses this to connect a tender gastank with a locomotive gastank on one of his models. Only thing is, it takes up a lot more space than plastic piping. Check out pneumatic / gas-plastic tubing. I'm sure you can find a kind that takes up to 140 degrees celcius, wich is what you get at 6 bar pressure. And you most likely aren't going to use higher pressure, right?!?
 

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Thanks Pauli, that might be worth checking into, and no I dont plan on getting anywhere near 6 bar! It warmed up this weekend, so I silver soldered the boiler together, and did some touch up soldering on a coal fired K-27 boiler I am working on. After hydrostatic pressure testing and some boiler firing to check things out, I will be installing the boiler and running some steam lines to tackle that articulation issue.
 

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Not to dredge up an old thread, but only to dredge up an old thread, Tim, what happened to this project? Inquiring minds want to know (O.K. well, at least me.) I have toyed with this idea for a while.
 

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Sorry guys, the project has been dormant, since it is in Boiler making stage, it has not progressed to the point of making the articulated steam lines. When I pick the project back up, I will post more.
 

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Posted By Tim Hytrek on 23 Feb 2010 05:34 PM
Sorry guys, the project has been dormant, since it is in Boiler making stage, it has not progressed to the point of making the articulated steam lines. When I pick the project back up, I will post more.


You haven't come up against anything that is unsurmountable have you? I've been having success building my boiler for my C-16 Alky conversion, and building a butane boiler to fit inside that huge shell should be able to be accomplished. How do the frames of the two locos compare?
 
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