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Discussion Starter · #1 ·
I am putting in a S curve using 20 ft diamater track. Do I need a "Transistion" track? A straight piece between the two curves. Does Body Mount couplers as compaired to Truck Mount couplers have any effect on if I use a Trasistion Track? Such as with Body mounts you don't need a trasistion track and with Truck mounts you do.
 

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RE: 20 FT "S" CURVE

I think they generally recommend a straight section as long as your longest car, usually a passenger car.

As you’re using a broad cure, it may not be necessary; I’d suggest laying it out and giving it a shot.
 

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RE: 20 FT "S" CURVE

I have a couple on my layout. I have a quick "S" behind my shed that is a 6' diamater that's just not workable, causes no end of headaches. I'll be replacing that in the spring.

BUT.. (a big but).. I have a 12' diameter "S" on the mainline that works just fine. Seems like the larger curves are gradual enough to be workable.
 

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Posted By John J on 12/30/2008 5:19 PM
I am putting in a S curve using 20 ft diamater track. Do I need a "Transistion" track? A straight piece between the two curves. Does Body Mount couplers as compaired to Truck Mount couplers have any effect on if I use a Trasistion Track? Such as with Body mounts you don't need a trasistion track and with Truck mounts you do.

jj save yourself alot of grief and do it right the first time and put a straight track in there. The Regal
 

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RE: 20 FT "S" CURVE

with 20ft dia. I wouldn't worry about it and if you are pulling a long consist body mount couplers are better as they let the trucks float and not tend to derail
 

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Posted By John J on 12/30/2008 5:19 PM
I am putting in a S curve using 20 ft diamater track. Do I need a "Transistion" track? A straight piece between the two curves. Does Body Mount couplers as compaired to Truck Mount couplers have any effect on if I use a Trasistion Track? Such as with Body mounts you don't need a trasistion track and with Truck mounts you do.






I have a big "S" curves with 8.5 ft radius and no intentional straight section in the middle and have had no problem with truck or body mounted couplers. It will depend somewhat on how much side play is in the coupler mounts and between couplers and how close the cars get coupled (length of coupler shank). But, 10 ft radius is a pretty big radius and I doubt you will have a problem without a straight section.
 

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Discussion Starter · #7 ·
I am correcting a mistake I have been ingorning for about 5 years. The container train has brought it to a head.

This is a picture of what did earlier. Since this pic was taken The rock mountians have been installed. But now I still got something to fix.

I am taking pictures as I go but it will be a while before I post them.




The New Grade and S curve wtill take me out to where that creosote bush is by the car.
 

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It's best to use a transitional piece of tangent track much like the real RR do. It's almost a requirement to prevent even the the slightest possibility of a derailment. I have 8 ft diameter S curve with a two ft straight between them. It's needed to operate the USAT pass cars. Better to do the track work right instead of pulling out what hair you may have and haveing to redo your track work. If room is availble do it. Later RJD
 

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JJ,
If you have the track why not just find a level place and do a test setup? Then you will know for sure what will work or not. I would probably use some straight in there anyway just because it will look better to the eye.
 

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RE: 20 FT "S" CURVE

I have a couple of S curves. All the ones less than the 20' diameter caused me problems. The 20' I've never had an issue.
 

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Posted By John J on 12/30/2008 5:19 PM
I am putting in a S curve using 20 ft diamater track. Do I need a "Transistion" track? A straight piece between the two curves. Does Body Mount couplers as compaired to Truck Mount couplers have any effect on if I use a Trasistion Track? Such as with Body mounts you don't need a trasistion track and with Truck mounts you do.




JJ,
It's just the opposite....truck mounted couplers will be more forgiving in a 'S' curve, however with 20 foot 'S' either type of coupler mounting should work just fine however a straight section will look better and will for sure eliminate the possibility of any problems in the future....
 

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I have an S made from 12.5ft dia curves without transitional straight. I can pull and push my Aristo heavyweights through it with no problems at all. They are fitted with body-mounted KD 789.



The join between the two curves is just a tie-space off the piture to the right.
 

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Posted By Dean Whipple on 12/31/2008 10:58 AM
Posted By John J on 12/30/2008 5:19 PM
I am putting in a S curve using 20 ft diamater track. Do I need a "Transistion" track? A straight piece between the two curves. Does Body Mount couplers as compaired to Truck Mount couplers have any effect on if I use a Trasistion Track? Such as with Body mounts you don't need a trasistion track and with Truck mounts you do.




JJ,
It's just the opposite....truck mounted couplers will be more forgiving in a 'S' curve, however with 20 foot 'S' either type of coupler mounting should work just fine however a straight section will look better and will for sure eliminate the possibility of any problems in the future....




I would agree, put a piece of straight track in for piece of mind..
Nick
 

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Posted By John J on 12/30/2008 5:19 PM
I am putting in a S curve using 20 ft diamater track. Do I need a "Transistion" track?





No, you don't need one. Don't sacrifice your 20ft curves and put tighter radius with a transition straight. There are no cars known to man that will not navigate an S made from 20ft curves even with body mount couplers. 20ft curves make a graceful S whereas 10 or 12ft with a straight in between looks clunky in comparison. Don't be put off by the scare stories it may have been true in Radius 1 and 2 days but everyone is putting in wider curves now and the fact is these longer cars and 6-axle diesels have no problems with S made from them.
 

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RE: 20 FT "S" CURVE

JJ you have the room, make it so it will be the safest way possible.
 

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RE: 20 FT "S" CURVE

Another opinion:

If you were running a loco and cars that required 20 foot curves, then I would think you would not want an S curve. I would guess things like Aster 1:32 locos, a big boy, etc.

But as fildowns says, you (probably) do not need to worry because almost everything else would shrug off an S curve of 20' radius.

Now, I have been talking operation only.

Appearance wise, I think back to back curves look toylike no matter what the radius. Also, if you are considering having your layout look prototype, I believe (R.J. ?) that prototype railroads ALWAYS had tangent track between curves of opposite direction.

So, if it was me, I would find a way to put a short amount of straight/tangent between the curves.

Regards, Greg
 

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Yes you may need one on aesthetic or prototypical grounds, just not for physically reliable operation. As to whether you think '10ft left+straight+10ft right' looks less toylike than '20ft left+20ft right' that is, as is a lot of things, a matter of opinion and personal preference.

I once saw someone's careful trackplan of 16.5ft curves with a short 1ft straight between them changed because he was bombarded with comments about "Ess bends with a straight shorter than the longest car possible are the spawn of Satan" (something along those lines...I'm probably exaggerating there...:)) His alteration to 8ft curves with a much longer straight was in my opinion a much more toylike substitute. From a graceful sweep that should have been a major photogeniic location on his railway now looked like a straight with horrible right-angles at each end, like it was taken straight off the living room carpet. And why? Well even though he was NG he "might want to run standard gauge with big pass cars one day..."

If we all had to go prototypical we certainly wouldn't be using 'toy-like' 20ft curves on the main! :)
 

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John,

Perhaps you could clamp the 2 pieces of curved track together and run a Train-li railbender over the junction to create a smoother transition between them. You'd have to reverse the railbender on each side and only run it to the join and stop. You might only have to slightly straighten each curve about 6".

Just a thought.

Doc
 

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RE: 20 FT "S" CURVE

Happy New Year all

I just got my main line up and running today.

It has all 8 foot diameter curves with an s curve and my little 2-4-0 Steamer pulling 14 MDC empty hoppers and an Aristo Craft bobber caboose are doing fine through it.
 

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Discussion Starter · #20 ·
RE: 20 FT "S" CURVE

I went out this moning fired up the back hoe. Used the loader to scrape off a bunch of creosote bushes and I am working on the 20 FT cuves again.
Will post pics at a later date. Mabye in another thread.
 
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