20-inch radius curves vs. 36 diameter curves

Mark -- this topic has been discussed before, e.g., here:  https://ogrforum.com/...29#77593417171617329

I think the general consensus is that Lionel is both confused and confusing.  Some of it appears to be trying to use a nomenclature they've used for O-gauge track - e.g. O-27, O-36, etc.  So they've used S36 in some places, even though they don't have curved track with a 18" radius.  Elsewhere they use R20, which is what most of us think of as the 'standard' curve track radius - dating back to the Flyer track made by Gilbert - which also applies to the Lionel reissue and the fast track.  They do offer a larger, R27 curved track as well (I don't recall if they make it in fast track).

So the answer to your question is no, there is no difference.  I wish Lionel would pay attention to this detail and not continue to be confused or confuse others...

Thank you. Since we are on the topic of previous discussions, where is the "search" tab on our forum? It used to be at the top and at another point, on the bottom. I would have looked it up. They say there is no such thing as a dumb question, but this has to qualify. but its frustrating.

Mark

Upper left corner click on the "Menu" button. The third choice down is "Search". I then choose "Advanced Search".

barrister.2u posted:

Lionel Flyer Chief makes a distinction for some locomotives needing a minimum curve of 36 inch diameter and other non FC items needing a 20-inch radius.

My question: Aren't they the same?  Doesn't a  20-inch radius translate into  a 40-inch diameter and if so, how is that different from a 36-inch diameter minimum radius?

Is there a difference and if so, what is it?

Mark

It a result of "Cut-'n-Paste-itis" by Lionel's catalog people copying the features from the Traditional O line.  They have a habit of copying O36 and translating it to S36.  Lionel doesn't make 36" diameter track in S, which would be 18" radius curves.  

S36 would be 36" radius, meaning a 72" diameter circle.

Rusty

Just to footnote what Lew said - using the 'advanced search' function, you can narrow down the topic - which can be very helpful.  The other 'box' I always check is to do the sort by date, not by relevance (which seems to be the default).  The search function overall seems to be quite good.  My first response wasn't intended as a "look it up" response - I went back and looked it up to remind me what the general consensus is/was (cut and paste run amuck, as Rusty sez).

the difference is clearly stated in the first post - 40 inch diameter vs 36 inch dieamter.     36 inch diameter is 4 inches smaller - a little more than the width of your hand.    A locomotive that can go around a 40 inch diameter may not be able go around a 4 inch smaller diameter 35 inch curve.    They are not the same!     40 inches is not the same as 36 - at least with my rulers!

PRRJIM - yes but.  The difference here is in the labeling used, not in the actual diameter - as you will see in the discussion in this thread and in the linked thread.  Flyer did not and Lionel does not make two different S gauge curved tracks with radius/diameter of 18/36" and 20/40" (they did and still do make a larger radius/diameter curve of 27/54").  So the issue here is the inconsistency in labeling by Lionel as applied to exactly the same radius/diameter curved track.  In their catalogs, Lionel says "minimum curve: S36" and "minimum curve: R20" seemingly interchangeably - for example, for the EP-5 (p. 109 of the current catalog), it sez R20 while for the U36C on p. 108, it sez S36.  Nevermind the fact that the wheelbase for the EP-5 is shorter than that of the U36C...   BTW, the S gauge fast track sold by Lionel is clearly labeled R20 and R27...

I suppose, trying to give Lionel some credit here , maybe they are trying to say that if you are using flexible track, you shouldn't make the curves tighter than S36 (R18) or R20.  Of course, that seems completely inconsistent with the EP-5 vs U36C comparison above...

At the end of the day, I think Rusty has it right

Rusty has it right. The 36" diameter is just some advertising copy run amuck. All it is trying to say is the S gauge Lionel flyer trains will run on S gauge FasTrack or original Gilbert track. There is no 18" radius sectional track made commercially so Lionel has not tested items at that radius. They are not carefully bending flex track to 18" radius for product test purposes.

More significant is the change in measurement protocol. When Gilbert made track the 20" radius was to the outside of the ties, so measured to the centerline as we do today the Gilbert track is actually 19" radius give or take a 1/16th of an inch.

I ordered an S-36 from Charles Ro, the Erie FC Berk. My smallest diameter is composed of 20-inch radius track, making it a 40 inch diameter. I will see what happens.

Mark

You will be fine...

So Tom (AMFLYER), are you saying that Lionel's flyer fast track, which is listed as R20, is actually 20 inches in radius to the centerline, which is a different radius (by about an inch) than the original Gilbert flyer track (see my recent "exact" measurements post)?

The FasTrack should be 20" to the centerline, I do not have any to verify it. The old SHS 20"R was actually 19" like the flyer track, a labeling problem again. The SHS 24" and 29" are correct sizes to the centerline. This seems to only occur in S gauge because of the original Gilbert track being measured incorrectly. If someone has a circle of FasTrack hopefully they can confirm the diameter of the 20"R track.

I have the Lionel S gauge FlyerChief Berk. It runs fine on Gilbert and on SHS track.

I am very impressed by the level of interest and expertise demonstrated. Many thanks.

Mark

AmFlyer posted:

The FasTrack should be 20" to the centerline, I do not have any to verify it. The old SHS 20"R was actually 19" like the flyer track, a labeling problem again. The SHS 24" and 29" are correct sizes to the centerline. This seems to only occur in S gauge because of the original Gilbert track being measured incorrectly. If someone has a circle of FasTrack hopefully they can confirm the diameter of the 20"R track.

I have the Lionel S gauge FlyerChief Berk. It runs fine on Gilbert and on SHS track.

And just to keep it interesting, I'm starting my Xmas layout using SHS S-Trax.  Some of the #00292 curved track boxes are labeled 24" radius and some are 25" radius.  Haven't seen anything but 29" for the big curves and the smaller radius I have is from MTH and is very definitely 20" radius.  All dimensions are to the centerline.

Tom Stoltz

in Maine

I have been modeling in 2 rail for many  years.    When I first got into, there was not even flex track, we had to hand lay our track.    My current layout is mostly flex track with a bit handlaid.     When I commented it just never occurred to me that people think in terms of fixed radius sectional track.      Every radius/diameter issue I have dealt with for years has not had that kind of restriction, so 36 in radius vs 40 inch radius is a valid question - is a difference and may be significant.     I had no thought of over riding sectional track restrictions.

Many use sectional track. I use it for the temporary Holiday layouts I build. My larger permanent layout is all flex track with #5,6&8 turnouts.

AmFlyer posted:

Many use sectional track. I use it for the temporary Holiday layouts I build. My larger permanent layout is all flex track with #5,6&8 turnouts.

Me too... and I don't set it up every year.  Last time was 2016.  This year wife wanted it on a platform so it is very different from previous years.  Three trains on  three separate loops with elevations.   Think I bit off more then I can chew...

Tom Stoltz

in Maine

Tom, that sounds like a lot of work. I keep mine to one level. I hope you can get it done.

At my old house, my Christmas layout was on the floor--albeit on plywood on the floor, and the tree on a platform so I could run trains under it. I had a loop, with a siding for the oil drum loader, then the next year I added switches so I could store a train and had two different "runs" all on less than a full sheet of plywood. Hmm, somewhere I have a picture.

AmFlyer posted:

Tom, that sounds like a lot of work. I keep mine to one level. I hope you can get it done.

In order not to hijack this thread, I will start a new one – Xmas layouts 2019 – S gauge

Tom Stoltz

in Maine

I was assembling an assortment of track in preparation for building a Christmas layout. I grabbed the first two boxes of standard radius track in the storage crate. We see here that even SHS was not sure what they made or they were unsure how to best market it. I assembled a circle for measurement. It is 19” centerline radius, the same as the original Gilbert track. Circles of the two types of track lay right on top of each other.

AmFlyer posted:

I was assembling an assortment of track in preparation for building a Christmas layout. I grabbed the first two boxes of standard radius track in the storage crate. We see here that even SHS was not sure what they made or they were unsure how to best market it. I assembled a circle for measurement. It is 19” centerline radius, the same as the original Gilbert track. Circles of the two types of track lay right on top of each other.

Tom That's what I found with the 24"/25".

I'm using 19 9/16" centerline radius in my CAD drawings for the 20"R curves.  My small radius track is all MTH, don't know if that makes a difference.  But I obviously put together a circle a measured it to come up with that.  I did it the same day I measured the other radii and they were 24" and 29", that was 3 years ago.  However now I'm questioning my results, seems strange in light of the other two...

Tom Stoltz

in Maine

I got out the SHS track and made circles of all 3 diameters, the 19/20, the 24 and the 29. I do not have any boxes marked 25" or 30". The circle centerline diameters are 38", 48" and 58". This makes complete sense to me as a track system if the starting point was duplicating the original Gilbert track size and radius. The MTH era production of this track would be the same. I am curious what the FasTrack is but I do not have any to test. Lionel markets it as 20"R and 27"R curves.

Tom -- nice job!  So SHS (and now MTH) seems to use the sensible labeling of track radius to the centerline (well, except for their confusion about the two labels for the same track).  Just for grins I looked on Doug Peck's Portlines site and here are the numbers used for other S-gauge track makers:

Gargraves (labeled as diameters):  42, 54, 63 and 72", where 8 sections make a circle

American Models (radii):  21, 24, 27" (12 sections to a circle)

American S-Gauge track (radii):  21, 27" (12 sections to a circle

Flyonel Fastrack (radius): 20" (12 sections to a circle) -- (I thought there was a 27" radius track also?)

So clearly we need more measurement data!

- Rich

Ok boys and girls, here are the measurement results for the AM 27"R track and the Lionel 20"R FasTrack. First, AM markets 21"R, 24"R and 27"R curves. I have some of the 27"R curves that were included in their older sets. I have one Lionel set that included Fastrack. They market 20"R and 27"R.

The AM 27"R track makes a 54" diameter circle measured center to center. So it is correctly marketed to current track measurement standards.

The Lionel 20"R Fastrack makes a 38" diameter circle measured center to center. It is the same as the SHS/MTH track, it uses the old Gilbert protocol for radius measurement.

I do not have any 27"R FasTrack to measure, but I do have some of the old K-Line Gilbert style 27"R track. I have it in storage, when I find it I will post its dimensions. I do not have any American S gauge or GarGraves sectional track.