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Author Topic: Big Engines, small curves  (Read 5194 times)
rustyrails
Guest
« on: April 23, 2009, 07:39:33 PM »

I'm starting this thread because I didn't want to hijack the My First Steam Engine thread.  In that thread, jbsmith writes about his new 2-8-4 (a really handsome locomotive) and notes that it will not go through an Atlas Tru-Track switch without derailing. 

Atlas Tru-Track is based on the the company's venerable "snap track" line.  A "snap switch" through the diverging route is the equivilent of 1.5" of straight track and then 2/3 of an 18" radius curve through the frog.  I don't know exactly, but I suspect that a snap switch approximates a number 2 frog--an impossibly sharp angle. 

In 1998 the 3rd edition of Robert Schleicher's HO Model Railroading Handbook was published.  Mr. Schleicher is a professional model builder/model railroader,  His book is interesting, in part, because in it, he builds a layout using what were then "new" materials--specifically Bachmann's EZ-Track and expanded styrofoam insulation.  He says, "Do try to limit your purchases of locomotives to 8-wheeled or smaller diesels and 53-scale-foot or shorter freight cars if you have only 4 X 8 feet or less of layout space.  The shorter equipment looks more realistic on the tight curves. "  He has a corresponding "Don't" that basically says don't try to run big stuff until you can have room for at least 24" radius curves.

I guess my point is that we need not make problems for ourselves fighting derailments and poor performance.  Just because 18"R track exists doesn't mean we have to run our largest loco on it.  An 18"radius curve is about 135 real feet.  Can you imagine a 100 foot locomotive REALLY going around a curve that sharp?  It's your railroad, but I propose that if you run equipment that "fits", you'll enoy it more.  Just my two cents worth.  Hope I didn't offend anyone.

Rusty
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pdlethbridge
Guest
« Reply #1 on: April 23, 2009, 08:29:44 PM »

If we ran trains according to the most used radius, we'd be running 2-2-0s and 2-2-2's. I have all small engines, the biggest is a decapod and it really looks out of place on my 22" radius curves. I guess it's all in the eyes of the beholder.
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rustyrails
Guest
« Reply #2 on: April 23, 2009, 09:03:29 PM »

I have some 18"R curves of necessity, but like you, I run small power...a couple of early Geeps, a 44 tonner and a modernized 4-4-0.  The B&O E-units sit in a place of honor in the display case, and when they're good, I take them to the club for a workout.   Grin

Rusty
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uncbob

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« Reply #3 on: April 23, 2009, 09:07:41 PM »

I have 2 oval layout with an 18 and a 22

My rolling freight is limited to 40' or shorter

My largest passenger cars are Old Time Overlands --they stay on the 22"oval

I run my 4-8-2 and 2-8-2 only on the 22"
The 2-6-0  2-6-2  4-4-0  4-6-0 are used on the 18"
My 2-8-0 run on both

I just added a 4-8-4 and it runs the 22" decently

However I am going to add 4"to the width of my layout and run 24 and 22 ovals
The 18 will go  bye bye
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jbsmith


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« Reply #4 on: April 23, 2009, 09:39:51 PM »

hey hey thanks for the input!
Well,,for many people it is a matter of space.
Not all of us can dedicate the Entire basement to a layout like we see in MR magazine. And some of those layouts,,WOW! Outstanding job!
I wish i had the space and $$$ for a layout like some of those!
I mean in some of those photos you really have to LOOK to determine
if it is the real thing or a model. Cool

So,,some of us have to make do and do our best with what we got.
In my case,,space available limits me to 22 inch curves on the outer loop
and 18inchers on the inner loop with switches connecting the two.
Got it set up so two trains can run in opposite directions, and
all in all it looks good enough to my eye.
Almost all of my rolling stock is 40 and 50 footers. A few 50+ foot hoppers
thrown in.
 An addition of a second 4x8 is the plan, and that will max out the space available. Might even get a 3rd 4x8 and rip it length wise to widen things
by a foot,use the rest for whatever, but that is in the theoretical stage.
Time to get the tape measure out.

It has been driving me Nuts as to HOW the 4-8-4 Niagara can go through
those curved turn outs in those switches without any problems whatsoever
and the smaller 2-8-4 Berkshires derail everytime!
My Diesels don't even seem to notice the switches when they use them.

The only solution I've found so far is to Not take the Berks through the
switch,,just keep them on the outer or inner loops.

Maybe if I some how splice in/ replace the switches with #6 turnouts?
The #6 do not appear to have as sharp a turnout angle as the
"basic" model turnouts that i currently have. Would have to use cork roadbed,to keep things reasonably even,but that can be disguised without to much of a problem. Just might get a couple of #6s' and test this.


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jward


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« Reply #5 on: April 23, 2009, 11:12:49 PM »

i would not use the snap switches or any other switch with an 118" radius curve as part of a crossover between your two loops. why? well unlike most switches, the curved route maintains that 18" curve all the way from the points to the end of the switch. using two of them in a crossover is like making an 18" radius s curve with no straight between the opposing curves. this is a HUGE mistake as explained in any book on track planning.
no wonder your 2-8-4 has trouble with that crossover.

numbered switches, even #4, have a short section of straight through the frog, and thus avoid the s curve that wreaks havoc on your equipment. any number of switch will be a major improvement, the larger the number the better. but even if you are short on space, using a #4 crossover will use up only slightly more room than what you now have, and you'll like the decrease in derailments that will result.
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Jeffery S Ward Sr
Pittsburgh, PA
grumpy

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« Reply #6 on: April 24, 2009, 01:03:46 AM »

There are some large engines that will run through 18" very well . I have a 4-6-6-4 Challenger that goes around 18" curves magnificently. I have a BLI 4-8-4 that also goes through 18"curves . My 2-10-2  will go through 18' curves while my 2-10-0  will not . A lot has to do with the mfg , the spacing of the drivers  is there a set of blind drivers and are you looking at the loco from an aesthetics point of  view or from a practical point of view . Everything cannot be brought to scale and matched . If you want to run large engines on your track do so . There are many large engines that will run 18" curves without problems. I do it so can you.
Don
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jward


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« Reply #7 on: April 24, 2009, 10:13:05 AM »

the problem is not the 18" curve per se, but the crossover that has two of them in an s curve without any straight track in between. my grandfather used to run a mallet 2-8-8-2 and a 2-10-2 through 18" curves. but there were no s curves without at least 9" of straight track between the curves.
they looked horrible but ran pretty well. i ran u30c's and sd45's around 18" curves successfully as long as the first car wasn't shorter than 50'.....
once again, no s curves without an intermediate straight....

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Jeffery S Ward Sr
Pittsburgh, PA
Johnson Bar Jeff

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« Reply #8 on: April 24, 2009, 12:04:13 PM »

Not too long ago I picked up a late model (can motor) Mantua Pacific and a Hudson on eBay. I was surprised at how well they operated on 18-inch radius curves. Generally, however, out of preference, I run smaller power, usually nothing larger than a ten-wheeler steam locomotive or an F-unit diesel. For freight cars I stick with 40' or less, and for passenger equipment 60' or less. They all run and look--to me--reasonably well on 18-inch radius curves--to which I'm limited by space considerations.
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train with no shame
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« Reply #9 on: April 24, 2009, 02:52:15 PM »

i also have 18"rad curves . and an 18"rad upper loop. i took out my 22"rad outter loop . and put my up 4-8-4 santen fa . as it was having problems on the #5 ez track switches . i forget who said it . but looked like the engineer was getting whip lash .and was to big for the layout .rather than taking a chance of doing damage to the engine from derails . i got tired of the single 18"rad layout .and added back the outter 22"rad outter mainline .i missed the running of  train strings in both directions . i think i might try to run the 4-8-4 sante fa again . the hummidity here close to the coast kills my track. what rolling stock do you recommend to run along with this steam engine .or might i go to something smaller .peace to all markf
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DaveS

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« Reply #10 on: April 25, 2009, 01:05:54 AM »

Personally I think that Atlas TruTrack is not very well made to be polite. I built a layout with it and found that my light mountain would often derail at turnouts but I couldn't seem to see how. I also had electrical issues with these turnouts.
My solution was to rip out the TruTrack and replace it with Unitrack and all derailment problems were solved. The light mountain goes through a #4 unitrack turnout with no problems. I must confess that I went to #6 on the mainline which of course is far better. Yes Unitrack is far more expensive but when you examine a turnout you can see why.
Space just doesn't permit me to go beyond a 4x8 and generally I stick to small locos such as that beautiful little Consolidation that Bachmann makes. Nevertheless I have a soft spot for passenger cars and I like to see the mountain haul a small string of Athearn heavyweights. I must confess that I do stick in a few express reefers too as they are only 50 footers.
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Yampa Bob

Y.V.R.R.


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« Reply #11 on: April 25, 2009, 01:36:02 AM »

Hi Dave,
Do you mean that "beautiful little Consolidation that Bachmann used to make"?  I was very disappointed to see the non sound version dropped this year.

One of our fears was that factories would force us into sound, whether we want it or not. Such is the fate of the Spectrum Connie. 
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I know what I wrote, I don't need a quote
Rule Number One: It's Our Railroad.  Rule Number Two: Refer to Rule Number One.
DaveS

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« Reply #12 on: April 25, 2009, 12:40:38 PM »

Yes Bob, I do mean the Spectrum Connie but I have to confess that mine has factory sound and I do love it. I have a few other steamers with sound and the Tsunami is by far the best. I did have to turn the volume way down as it was just too loud as most are from the factory. Adjusting the CV's on that rascal takes a few tricks I learned on the MR forum but once done the lower volume makes it a lot better.
Dave.
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Eryalen

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« Reply #13 on: April 25, 2009, 10:03:24 PM »

I'm starting this thread because I didn't want to hijack the My First Steam Engine thread.  In that thread, jbsmith writes about his new 2-8-4 (a really handsome locomotive) and notes that it will not go through an Atlas Tru-Track switch without derailing. 

Atlas Tru-Track is based on the the company's venerable "snap track" line.  A "snap switch" through the diverging route is the equivilent of 1.5" of straight track and then 2/3 of an 18" radius curve through the frog.  I don't know exactly, but I suspect that a snap switch approximates a number 2 frog--an impossibly sharp angle. 

In 1998 the 3rd edition of Robert Schleicher's HO Model Railroading Handbook was published.  Mr. Schleicher is a professional model builder/model railroader,  His book is interesting, in part, because in it, he builds a layout using what were then "new" materials--specifically Bachmann's EZ-Track and expanded styrofoam insulation.  He says, "Do try to limit your purchases of locomotives to 8-wheeled or smaller diesels and 53-scale-foot or shorter freight cars if you have only 4 X 8 feet or less of layout space.  The shorter equipment looks more realistic on the tight curves. "  He has a corresponding "Don't" that basically says don't try to run big stuff until you can have room for at least 24" radius curves.

I guess my point is that we need not make problems for ourselves fighting derailments and poor performance.  Just because 18"R track exists doesn't mean we have to run our largest loco on it.  An 18"radius curve is about 135 real feet.  Can you imagine a 100 foot locomotive REALLY going around a curve that sharp?  It's your railroad, but I propose that if you run equipment that "fits", you'll enoy it more.  Just my two cents worth.  Hope I didn't offend anyone.

Rusty
I've had some success with softening the curves. Instead of going from flat to r18" go to r33' then r22' then r18'. It would approximate the ideal (I think) of a parabola to ease into a tight curve. It also alleviates the "swing" of the overhang going from straight to r18".
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rustyrails
Guest
« Reply #14 on: April 25, 2009, 11:01:57 PM »

Eryalen,
What you're talking about is called an easement.  Easements are very easy to lay using flex track, significantly add to appearence and reduce derailments.  You just need to provide for the small amount of extra space they require.  Almost any book on trackwork should show you how do easements.
Rusty
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