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I have minimum O72 curves and switches with larger radii on many curves.  Is it possible to run both freight cars (40' to 50') and scale length passenger cars that are two rail (body attached couplers) on my three rail track?  Anyone doing this?  Seems like the freight cars would be more possible.

Thanks!

Robbin

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IMO, may be fine but not super fine.  Frogs can be a flange picking problem.  Hope there is protection near switches for an unexpected launching to the floor.

Older GG rail has a more defined flange edge.  Dies wear over time.

Truck mounted couplers would work better than body mounted on scale length passenger cars. 

Our layout was all Atlas solid nickel silver, and once I modified all the turnouts (by adding styrene shims to the tops of each guard rail, so as to be the same height as the running rail), I had no more trouble with 2-Rail SCALE freight rolling stock (even reverse moves through turnouts). All equipment was up-graded to body mount Kadee couplers.

Concerning the curves, pretty much everything on the main lines was larger than 072, up to 099.

I did it in the 1970s with Athearn trucks and wheels, which are still same profile flanges today.    I did have to do what Hotwater did and put st yrenen shims on top of the guard rails to raise the top to height of the running rails.    I just painted them black and they disappeared.     My track was all gargraves at the time and 072, 36 inch radius curves.

I did not have any scale length passenger cars so I can't say on the.    The problem might be coupler swing with body mount depending on what they are couple to.     A possible solution is to filled the gaps in the shank and drill a hole for a screw.    then mount them like radial couplers on street cars so they can swing farther.     They won't self center.     If you want to go a bit farther, there is a small tab on the rear of the Kadee shank that is for connecting a spring.    You add another screw behind the shank and bend the box centering spring so it has a loop parallel to the car floor.   You connect that to the second screw and hook the other end of the spring to the small hole in the back of the shank, and you have self centering.     Both CLW and Kadee couplers were designed with this in mind.

We have several members in our club who run scale equipment on the club layout with Atlas 3 rail track and turnouts.  The scale wheels do a really good job of finding any kinks in the track.  All of the curves on the mainlines are greater than 072 (36" radius) and mostly #5 turnouts.

I do not know the details of which equipment or couplers the are running.

As mentioned above your 2-tail wheels will drop into the frogs as their flanges are not tall enough to carry the wheel through it.  If you ar only going to run 2-rail equipment then you'll need to shim the frog.  Otherwise, you'll just have to accept the noise and the operational problems.

Jan

Inquiring about 21" cars and minimum curves edges into a rather subjective realm.

Some folks want to run 21" cars on any curve where they will not derail regardless of appearance.  Fine

Other folks prefer to not see the outside rail when a 21" car is on a curve.  Also fine if you have the space.

I run all length passenger cars along with larger then normal curves however I find a string of my 18" passenger cars look best on my curves.

Even with curves on the small side I find the use of #7.5 or #8 switches look best with long cars.   All subjective opinion.

Anybody know what the minimum curve would be for body mount couplers on 21” passenger cars?

This is a general formula.

Measure from center to center on the trucks. Multiply that by three to get the minimum. Multiply by four (or more) for better appearance. For hi-rail cars you can usually get away with something smaller than the minimum, but it depends on how, closely the cars are coupled and how much swing they have.

I run Kadee #805 equipped 21 “ GGD heavyweight passenger cars. Gargraves track with close to 072 minimum. Pure 072 curves you will probably have issues. I built easements into my curves. Just went by my eye for looks with no real formula. Back in the day. The cars I ran were 15 and 18 inch. Going from a straight portion of track right into an 072 curve.  Which I had leading into in one yard area it was a no go. Instant derailment.
Longer version Kadee’s might work that offer more of a swing. If you want to go this route. I’d put 1 coupler on 2 different cars and couple them together and run them everywhere you would run them. There won’t be much to change out if you have to go back to square 1. If you can’t get them to work satisfactory your only other alternative would be to try to truck mount them. This may involve some work but is possible. I did this initially with some Weaver 60 ft. Baggage cars. Worked great till I coupled them to a car with body mounted couplers. All kind of derailments.

I run no longer than 50 ft. Freight cars with never an issue.

Thanks for the input on passenger cars. At this point I’m gathering information for layout planning. I’d like to convert all my equipment to body mount Kadees and fix the pilots on my diesels. Will leave the 3 rail wheelsets.
I figure the largest curve I’ll be able to muster is 0-96 (48” radius) so hopefully that is sufficient for 21” passenger cars to operate smoothly and not look horrible.

@AGHRMatt posted:

This is a general formula.

Measure from center to center on the trucks. Multiply that by three to get the minimum. Multiply by four (or more) for better appearance. For hi-rail cars you can usually get away with something smaller than the minimum, but it depends on how, closely the cars are coupled and how much swing they have.

That's close to what I was taught Matt. 3x the length of the entire car for reliable operation (some will go to 2.5x), 4x to look reasonable, and 5x to look really good and be able to couple body mounted Kadees on a curve.

That works out to the following for 21" cars:

  • 2.5x= 52.5"r or O-105
  • 3x= 63"r or O-126
  • 4x= 84"r or O-168
  • 5x= 105"r or O-210

This is why the shorter cars exist. It's really difficult to make passenger cars look realistic on curves in O scale. I struggle with this myself because it really bugs me when the diaphragms don't touch and when the cars open so wide on curves that people would fall between the cars if they tried to cross.

There are ways to mitigate the visual impact. In the past I've had good results with the following:

  • Keep track level as close to eye level as possible. Ie. don't look down on trains
  • Keep the viewer on the inside of tighter curves
  • Limit or do away with viewing curves from the outside
  • Use tunnels and/or view blocks for tight curves that the cars will go around but look bad on
  • One good way to "test" how cars will look is to use N scale as a mock-up. Full length cars are a little over 6". Lay out a 30"r curve and put a couple cars on it and see how much better they look.



Just some tips I've learned from the experts over the years. Hope it helps.

Last edited by jonnyspeed

Thanks for the input on passenger cars. At this point I’m gathering information for layout planning. I’d like to convert all my equipment to body mount Kadees and fix the pilots on my diesels. Will leave the 3 rail wheelsets.
I figure the largest curve I’ll be able to muster is 0-96 (48” radius) so hopefully that is sufficient for 21” passenger cars to operate smoothly and not look horrible.

They will operate no problem. How they will look is pretty subjective, but as I posted above they are not going to look realistic so it's up to you to decide if that's OK. Most serious passenger modelers in HO that I've met run a min. of 40-45"r which puts them right around that 4x range which would be roughly 84"r in O scale.

Passenger cars are the hardest thing to model to make look realistic IMHO. However, people that run on 3R track seem to be more willing to live with the compromise in my experience. Lay out the curve and throw some cars on there and see if you can live with it. Thats the best thing to do.

Last edited by jonnyspeed
@Robbin posted:

I have minimum O72 curves and switches with larger radii on many curves.  Is it possible to run both freight cars (40' to 50') and scale length passenger cars that are two rail (body attached couplers) on my three rail track?  Anyone doing this?  Seems like the freight cars would be more possible.

Thanks!

Robbin

It is imperative to check the clearance of underbody details when running on three rail curves.  If you have 3rd Rail heavyweight cars, the 60' baggage cars are probably the ones which are most suseptable to damage or derailing in tight diameter curves.  John

Anybody know what the minimum curve would be for body mount couplers on 21” passenger cars?

Well, I tend to draw on my years of investing in the land of (pardon me!) HO.

I would offer this simple comparison...

First of all, an O72 curve (36" radius) is equivalent to an 18" radius curve in HO.  Probably good enough for 40'-50' cars with body-mounted couplers.

When it comes to HO passenger cars, though, I reflect on the notation that some large manufacturers...like Walthers...would include on their RTR full-length (85') passenger cars.  They would specify 24" minimum radius.  In the O realm that would work out to O96 curves.  And this was to accommodate the body-mounted couplers on those cars...which still were designed to have some additional side-to-side flexibility over a fully rigid mount.

Other HO manufacturers...like Athearn, Roundhouse, Con-Cor, etc...would offer 'shorty' passenger cars...analogous to the 15" and 18" offerings in O3R...as a concession to  the popularity of 18" (sometimes 22") radius curves offered in complete HO train starter sets.

Bottom line re full-length scale passenger cars with body-mounted couplers?...I think you're going to have a LOT of problems on anything less than O96 (48" radius) curves.  Just a prediction, mind you...no personal experience.  Oh, and hope that you'll never have to back up a string of full-length passenger cars with body-mounted couplers through O72 curves and comparable switches, cross-overs, and ladder tracks...to name a few.  Rots o' ruck, pal!

Re wheel flanges...I also have Ross/Gargraves exclusively on the layout and often replace the plastic wheels on current production Athearn O trucks with metal wheel/axles (O2R) like those sold by Intermountain.  Very few major operational problems, but I haven't done anything with the switches...yet...and those cars (mostly cabooses from kits) do, indeed, have a bit of a dip and rattle going through the turnouts.  C'est la vie.

My layout is also built to O72 minimum curves.  There are many curves of larger radius...up to O128.  But I prefer running the 15" passenger cars.  They just look better snaking around the bends.  But that's IMHO.  I have longer cars...18"...but don't run them as often.  I have also succumbed to a very few select 21" passenger sets...GGD, only...for sentimental reasons.  Perhaps someday they'll stretch their 'legs' on a club layout with curves that complement their length.  Maybe.

The other advice, though, among the responses...try running O2R equipment, see what happens...is probably the best encouragement.   I'd avoid mach-level O3R around-the-tree speeds though!

Let us know how it goes!

KD

Last edited by dkdkrd

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