# Triplex anyone ?



## bille1906 (May 2, 2009)

Fellow Steamers
I am starting to draw up plans for an Erie Triplex but there is not much available on it
I was able to find the driver diameter and wheel bases but no other usable specs. I can use ratio and proportion to get other measurements from photos but non of them are straight on so some of it is guesswork 
If anyone has seen specs like height width length etc., it would be appreciated.
I think MTH did an electric one so their measurements might work

The other thing to consider is whether or not to make it compound. The original was, with the center cylinders the high pressure ones and the left cylinder feeding the two front cylinders and the right the rear or vise versa. The bore on the original was 34" for both HP & LP which scales out to 1-1/16" which is too large for our use and the boiler wouldn't supply it. My boiler design would probably support a 7/8" HP cylinder which has the same area as three 1/2" cylinders or possibly a 15/16" HP or three 0.550 cylinders
So the question is do i feel lucky and try the compound which would be awesome but could be as big a failure as the original Triplex or stay safe with three simple engines

your thoughts?


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## John Allman (Jan 2, 2008)

Even Erie found the boilers couldn't keep up with the cylinder's use of steam. So I guess that means don't make the cylinder bores anywhere near to scale. MTH definitely made one. While I don't have such a model, surely somebody on MLS has one. In my view, MTH did a fine job of scaling out the locomotives that they made. The boilers are too tall - to fit the electric motors, but the details and overall dimensions seem quite close to the steamers I have of the same locomotives.


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## bille1906 (May 2, 2009)

Thanks John
I think the Erie had two problems
1. the firebox was too small
2. only the front low pressure cylinder was venting through the smokebox and the draft was insufficient

My firebox will be about 50% larger and my burner will be ceramic gas which does not require a draft.
A smaller version of this is on my Ruby which supports 3/4" cylinders so I feel comfortable with at least 7/8" HP cylinders. Still not near scale


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## David Leech (Dec 9, 2008)

Bill,
Train Shed Cyclopedia index list that volume 1, 2, 18 and 31 have 'something'.
I have 31 but it's just a photo with relevant details of weight and some sizes.
Drivers = 63"
Driving wheelbase = 71' 6"
Total engine and tender wheelbase = 90' 0"
Cylinders (2hp - 4lp) 36" x 32"
Volume 1 shows 3 page numbers, so that 'may' be your best bet for drawings as well, but who knows!
Maybe someone here can tell you.
Cheers,
David Leech, Delta, Canada


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## bille1906 (May 2, 2009)

David
This is weird I found that file online and went back to check the dimensions and found that I had copied the Virginian specs that showed 56" drivers, 34" bore and 67.58' driver wheelbase
I thought that they were both the same and the Virginian had just had the rear pony converted to a pilot truck for running in reverse. Not so. Now I need to decide which one to do.


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## ConrailRay (Jan 2, 2008)

build the Erie Triplex!

http://www.rr-fallenflags.org/el/loco/erie2603.jpg

http://www.google.com/patents/US1013771

http://www.google.com/patents/US1171283

Sent you a few PMs as well!
-Ray


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## David Fletcher (Jan 2, 2008)

Just go to the horses mouth so to speak. No speculation, BS hobbiests making stuff up. Just go to the archives and get the original Baldwin specs and info, get what the designers actually specified. The specification you're after is in Baldwin spec Volume no 50, starting on P184. Its 14 pages of specifications, Highly detailed. The Virginian was a totally different loco from the Erie loco as well. 
You can down load the spec here:

http://digitalcollections.smu.edu/all/extra/degolyer/rwy/BaldwinManuscripts/mss0061_02_50_opt.pdf

If that link doesn't work, the page is this one:
http://digitalcollections.smu.edu/cdm/singleitem/collection/rwy/id/32

scrol down to Vol 50, download it, and then go to page 184. This is the hand written number on the top of the page, not the PDF page number.

Vol 5 has the first one built, known as 'drawing 1'. The 2nd and 3rd were built a couple of years later with some changes, which became the drawing 2 design. For the 2nd order, the specs are in Vol 55, p128.

Vol 55, P187 has the Virginian Spec

I'll go check whats in the drawing archive. I suspect MTH used original original drawings. Most of us do when designing locos for model Cos.

Hope this helps,
David.


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## David Fletcher (Jan 2, 2008)

If no one has sent you the Baldwin GA drawing yet, drop me a line. I have it. It was published in the 1922 Locomotive Encyclopedia. Not sure which archive has the original - not at Degolyer, although many drawings are incorrectly listed so it takes time. I'd look at the Standford collection and Smithsonian, but given its published in a 1922 book, dont need to hassel those nice ladies at the Libraries.

Good luck,
David.


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## steamtom1 (Jan 2, 2008)

You mean something like this, from Diamondhead, back in '05?


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## bille1906 (May 2, 2009)

Tom
I hadn't seen that one. Is it a Roundhouse conversion?


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## steamtom1 (Jan 2, 2008)

Bill,
Afraid I can't help you. I just saw it sitting there, and snapped the photo. I'm not sure it even ran. Perhaps someone else can help out. Roundhouse chassis parts sure look like they might do the job though, except, as I investigate, it looks like Roundhouse never did an 8 coupled chassis.


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## bille1906 (May 2, 2009)

I got some great drawings from David Fletcher which should make this project easier to design
He is a wealth of information and explained to me the three versions of the engine.

I am still not sure about compound or simple but am leaning towards compound
I see where the prototype didn't have any start-up valving to convert to simple as it was felt that just a few revs on simple with those huge cylinders would deplete the boiler of steam. So I would do the same and maybe as a fail safe have a valve to vent to atmosphere the high pressure cylinder exhaust at startup and then switch to compound once the HP cylinder condensation is ejected.

As always, I appreciate any feedback on the subject


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## lotsasteam (Jan 3, 2008)

regner build a good working compound engine,someone in the "buntbahn" forum modified it so its very reliable,will check it out again and post info,Manfred


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## lotsasteam (Jan 3, 2008)

reppingen has made a "compound"mallet which is actually a hybrid:starts which regular pressure on all four cylinder and through a special valve switches to "compond" mode.


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## bille1906 (May 2, 2009)

In studying the problems with compound engines in models, the main problem seems to be condensation in the low pressure cylinders at start-up
I make a very efficient automatic cylinder drain which I will be using on this engine but I am not sure they will handle the amount of water which will be produced here
There have been problems with diverter valves on compound models and since this will be a complex engine, I don't want to introduce anything that could cause problems in the future so here is what I was thinking
I forget most of the information I gathered for my Compound Heisler but I do remember that many of the compound engines had a supply tank that held the HP cylinder exhaust to ensure the LP cylinders always had a full charge. Maybe a tank (or two) like that with a larger cylinder drain would expel most of the water before it got to the LP cylinders ???


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## Kovacjr (Jan 2, 2008)

Bill, Problem with the Regner compound valves is they seem to always use the 2 part rotary valve. Hoping that the spring is enough tension. They do make a internal rotary valve that has no external springs, Ill have it at NSS if you want to look at it. Though can't see the internals but its just the same as the 2 part ones. Nice part is its all sealed and doesn't leak. 

One other option is to make only 2 engines operational that way steam consumption is more reasonable. Or use a much smaller cylinder for one engine just for effect.

Being the lines are far runs what if you had the exhaust plumbing route through the boiler for the exhaust to the low pressure, it would keep it warm for the longer run. Just a simple in and out like a pass through throttle.

I think Ray is getting too excited about this project! Will this be his wedding gift? HAHAHA.


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## bille1906 (May 2, 2009)

Jason
I am planing on running the rear one alongside the firebox, May even clamp it to it. The front will be more of a problem but it will be heavily insulated. naturally the HP will be superheated 
The smaller cylinders appeal to me for less steam consumption, but for some reason, I keep pushing the envelope on cylinder size. I can always sleeve it but it is not always possible to enlarge the bore.


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## lotsasteam (Jan 3, 2008)

The G 4/5 from regner is a compound engine ,"Buntbahn" builders changed the design of the engine so the low pressure Cyl receive superheated steam which worked very well according to their experience!


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## seadawg (Jan 2, 2008)

The G 4/5 also used the original compound / simple valve that Jason spoke of above. When the boiler approached 3.5-4 bar the steam would vent through the valve, even after adding a larger spring and compressing it a lot. My REGNER IV K uses the newer designed enclosed valve and works very well. I believe Rod Blakeman converted his IV K to straight simple steam.

It does take a long time to clear all the condensate. But once cleared, the simple / compound works well.

The REGNER TSSD is a horse of a different color. It does NOT have cylinder drancocks and takes FOREVER to clear the condensate. It also uses the externally sprung compound / simple valve.


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## bille1906 (May 2, 2009)

I think cylinder drains are a must. You don't want to stand too close to my compound Heisler or you will get a hot water shower. Well, maybe more like four squirt guns going off. 
Think of the amount of water that comes out of the exhaust and smokebox on a regular engine on start-up going into another set of cylinders... lockup ???

Another design issue is the cylinder sizes. I used 1.7 times the HP cylinder cross section for the the Heisler LP cylinder which is what Aster uses. Full size engines used 2 - 3 times the cross section at a much higher pressure This shows the LP bore using the 1.7 ratio with various size HP cylinders. Or, I probably could run it at 80 PSI and do the same bore for all cylinders ???

HP bore Area Ratio Cyls LP Area LP Bore
0.625 0.31 1.70 2 0.26 0.58
0.750 0.44 1.70 2 0.38 0.69
0.822 0.53 1.70 2 0.45 0.76
0.875 0.60 1.70 2 0.51 0.81
The table won't transfer over so here are the bores
LP / HP
.675/.580
.750/.690
.822/.760
.875/.810


Any thoughts ???


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## BigRedOne (Dec 13, 2012)

Do you think there is merit to considering reducing the bore of the third engine, relative to the first?

I'm curious if weight distribution presents a risk of the rear engine slipping more than the others.


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## bille1906 (May 2, 2009)

The third engine caused a problem on the prototype when It got low on water and coal. My tender will have a gas tank and hand & axle pump and I will be adding water as it runs so it won't be drastically lighter.
However, in reading up on model Mallet compounds, I understand that the LP engines tend to slip more than the HP ones which doesn't make sense to me having 1/3 the pressure and only 1.6 - 1.7 times the area, unless the back pressure on the HP side is seriously limiting it's power
In any event, I am leaning toward smaller LP cylinders and should be able to fine tune them by advancing or retarding the timing...I hope


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## rodblakeman (Jan 2, 2008)

Dave, My IV K runs in compound with the enclosed compounding valve, drain cocks are a must have and I run the IV K with the LP drain cocks open for the first few minutes to get the cylinders warm and clear of condensate. The steam lines are all insulated as well.

My TSSD has the same IV K set up with the IV K cylinders/drain cocks and the enclosed compounding valve replacing the old disc valve version.

https://picasaweb.google.com/114036153408224749848/IVK#5851922542494254674


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## bonzo1953 (Dec 27, 2007)

John van Riemsdijk (JvR) had a lot of input on the early Aster compound engine designs. I recall an article by JvR in G1MRA about sizing the LP cylinders with respect to the HP cylinders. 

I have the JvR G1MRA book. A compilation of his G1MRA articles.
You can look them up on line: http://www.g1mra.com/members-area/old-newsletters-and-journals/
‘Tales of two compounds’ October 1983 119/14 
‘A Gauge One Compound Pacific’ April 1989 141/7 
‘Driving compounds and some others’ April 1989 141/11
’Gauge One Compounds’ April 1998 177/20
‘A two cylinder compound’ Summer 2005 206/24 “Throttling the steam to 50lbs in the H.P. steam-chest (about the minimum for proper compounding) would certainly reduce the L.P. share of the work, unless, perhaps, I shortened the cut off’s by a little bit.” 

I believe the RH&LLR Triplex in Steamtom1's photo was made by Dick Abbott of Ontario Canada. It had just been completed and had not run when DH rolled around. Dick is also a G1MRA member.

Keep 'em Steamin'
John


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## bille1906 (May 2, 2009)

John
Thanks
I read a JvR article on the 1:1.7 ratio and cutoff ratios before I did my Heisler Compound
I still don't understand everything he does but it worked out on the Heisler so I won't veer far from his ratios on this one.
The link you sent is password protected
I have been meaning to join G1MRA for a while now. I guess now is the time.


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## bonzo1953 (Dec 27, 2007)

For G1MRA membership drop Ernie Noa a line. [email protected]

Access to the past Newsletter and Journal's is worth the price of membership.
You will also get a list of members with contact information.

Keep 'em Steamin'
John Garrett
Ballwin, MO


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## rwjenkins (Jan 2, 2008)

bille1906 said:


> I understand that the LP engines tend to slip more than the HP ones


A big part of that is probably to do with weight distribution, since the LP cylinders are typically on the front (articulated) engine on a Mallet. I would imagine the rear (fixed) engine bears more weight.


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## bille1906 (May 2, 2009)

I agree Richard
I believe that is compounded when the rear fixed engine tries to do a wheelie thus raising the front of the boiler slightly


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