What’s the REAL minimum radius of locomotives and rolling stock?

[Drumguy]

gdelmoro

 

 

Drumguy

I think the biggest factor in the minimum radius game is speed. The manufacturers are trying to market to the largest possible base. Therefore, “minimum radius” is a more desirable advertising metric than “desirable radius.” More folks have minimum 22’s Than 32’s +, so they tell us it will work on a 22. It’s not deceptive advertising, it’s just marketing. It will work on a 22—at 10% throttle. For mainline passenger speed, it will need something significantly wider.

My minimum radius is 26, most are 30, but I like those big articulated steamers, so I’m willing to slow them down to navigate that 26” curve.

 

 

 

 

That’s interesting Drumguy, Are you talking about decopods? Or Big Boy locos.  I have never tried them because i thought it just wouldn’t work.  I have a 1990’s riverarossi 4-6-6-4 I’m thinking of converting to DCC but I really would like to find some way to test run it first.

 

I have a BLI 2-8-8-2 cab forward, BLI T1 4-4-4-4, a BLI Challenger 4-6-6-4, and they will all run a 30” curve at full throttle—but slower is safer and looks better. All of them can handle that one 26” curve at full throttle, but makes me a bit nervous and it looks stupid. But it is what it is, due to the odd shape of my room, I had a spot that simply required a tighter curve. I slow the T1 a bit more on curves— it’s not articulated, so very unforgiving, although it is extraordinary well engineered, IMOP. BLI Big Boy will be here in a week or two. We‘ll see how that one fares.

[gdelmoro]

Drumguy, please let me know how the Big Bou does. Good to hear the Challenger holds a 26. I would like to get a couple of those larger locos added to my collection.

[Paul3]

The 18" radius crowd is a drag on the hobby.  Look, if you want to run trolley-like curves, run trolleys.  Is that so hard to figure out?  If you must have 18" curves, don't buy 89'/85' cars.  Don't buy 6-axle diesels or 8-coupled steamers.  Just stay with 4-axle/6-coupled locos and 40'/50' cars, or if you must run passengers buy the old toy train stuff with truck-mounted couplers.  Stop demanding that high-end scale models in excess of 50' long must go around ridiculous curves.  Live within the reality of short curves.  Goodness knows there's plenty of shorter models already out there.

Sheldon,
My problem with the shorty passenger cars is that they look like Lionel 100% of the time.  My 85' cars may look like Lionel on 30" curves, but on the straights and in the terminal, they look realistic.  And since my old layout had more straights then curves, they looked better most of the time.

[ATLANTIC CENTRAL]

Paul3

The 18" radius crowd is a drag on the hobby.  Look, if you want to run trolley-like curves, run trolleys.  Is that so hard to figure out?  If you must have 18" curves, don't buy 89'/85' cars.  Don't buy 6-axle diesels or 8-coupled steamers.  Just stay with 4-axle/6-coupled locos and 40'/50' cars, or if you must run passengers buy the old toy train stuff with truck-mounted couplers.  Stop demanding that high-end scale models in excess of 50' long must go around ridiculous curves.  Live within the reality of short curves.  Goodness knows there's plenty of shorter models already out there.

Sheldon,
My problem with the shorty passenger cars is that they look like Lionel 100% of the time.  My 85' cars may look like Lionel on 30" curves, but on the straights and in the terminal, they look realistic.  And since my old layout had more straights then curves, they looked better most of the time.

 

Well Paul we have been down that road before, and I'm not interested in another trip.

I will only say, once again, for the 300th time, not every passenger car ever built was 80-85' long........ and I don't model the New Haven........

With your other comments, I agree completely. Yes, I'm a "radius snob", 36" is my bare mainline minimum. Most are more like 42".

Sheldon

[riogrande5761]

Paul3

The 18" radius crowd is a drag on the hobby.  Look, if you want to run trolley-like curves, run trolleys.

Basically this is my mantra as well.  Unfortunately the intro to the hobby for so many is the old 18" curve supplied in most train sets.  Ug!

 

[BRAKIE]

riogrande5761

 

Paul3

The 18" radius crowd is a drag on the hobby.  Look, if you want to run trolley-like curves, run trolleys.

 

 

Basically this is my mantra as well.  Unfortunately the intro to the hobby for so many is the old 18" curve supplied in most train sets.  Ug!

 

 

And we will forget about the skilled modelers among us that is force to use those 18" curves.

Everybody isn't lucky to have a full basement for a layout nor the funds to build a special layout building or join a super nice club with a super layout. These modelers make do on what the space allows.

I have notice the growth of shelf  switching layouts so,maybe the old 4x8' looper with its tight curves is falling from favor?

 

[wjstix]

I think as has been mentioned, the problem isn't really 18" radius curves so much as people - often 'newbies' - expecting to run SD90s and 85' automobile cars on them. When I added the first "blob" to my shelf layout for a reverse loop (28"R), I was able to fit inside of it a 22"R oval of track with a switch coming off it leading to a two track 'yard'. I call it my "high line" (it's elevated 4-5" above the main) or "logging line" as the 'yard' is based on a small logging camp. It's just a oval using one 9" straight section on each side, but my small steam engines and older style 36'-40' cars are fine on it. My Spectrum 2-10-0 can take around 80-90 seconds to go once around the oval.

Plus it's a lot easier for doing break-in runs on new engines than setting up the oval on the floor in the living room was!

p.s. Athearn heavyweight RPO, Baggage, and Coach cars are all models of cars that actually were less than 80'. I think the Coach is 70' (as were many real coaches) and the head-end cars are both around 67'. The Walthers / Rivarossi 60' RPO, Baggage, Coach and Combine are also all based on real cars that were only 60' long. (Many railroads had 60' RPOs.)

[ATLANTIC CENTRAL]

Silly computers.......

[ATLANTIC CENTRAL]

BRAKIE

 

 

riogrande5761

 

Paul3

The 18" radius crowd is a drag on the hobby.  Look, if you want to run trolley-like curves, run trolleys.

 

 

Basically this is my mantra as well.  Unfortunately the intro to the hobby for so many is the old 18" curve supplied in most train sets.  Ug!

 

 

 

 

 

And we will forget about the skilled modelers among us that is force to use those 18" curves.

Everybody isn't lucky to have a full basement for a layout nor the funds to build a special layout building or join a super nice club with a super layout. These modelers make do on what the space allows.

I have notice the growth of shelf  switching layouts so,maybe the old 4x8' looper with its tight curves is falling from favor?

 

 

Larry, luck has very little to do with it, I still work hard every day at age 60 to provide a nice lifestyle for my family..........

There us nothing wrong with 18" radius, just don't complain that your $80 a piece high detail RTR 80' passenger cars will not go around them.

Sheldon

[BRAKIE]

ATLANTIC CENTRAL

Larry, luck has very little to do with it, I still work hard every day at age 60 to provide a nice lifestyle for my family..........

A lot of modelers work hard every day and still not lucky enough to have a full basement,funds for a layout building or a nearby club. You heared on the news how the middle class is struggling.

Even when I worked on the railroads I never had the funds for building a special layout building nor did I have a full basement-my son and his friends claimed that for their D&D game table,my son's pool table and the wife claimed what was left for a chest freezer and washer and drier. 

[SpaceMouse]

BRAKIE

Everybody isn't lucky to have a full basement for a layout nor the funds to build a special layout building or join a super nice club with a super layout. These modelers make do on what the space allows.

Just so you and everyone knows, the minimum radius on my mainline is 19.6"

18" users, I thumb my nose at you.

[BRAKIE]

SpaceMouse

Just so you and everyone knows, the minimum radius on my mainline is 19.6"

That should be a half step above the 18" curves and still on the sharp side.

Even being freight only ISL I wouldn't settle for anything less then 22" since industrial curves can be sharp..

[SpaceMouse]

BRAKIE

Even being freight only ISL I wouldn't settle for anything less then 22" since industrial curves can be sharp..

What I didn't say was that those curves are in a tunnel and all you see is the straightish stuff. Plus my long cars are 34' and my biggest engine is a Roundhouse old-time 2-6-0. 

That does not include the climb to the logging camp made by the geared engines. I admit I have a 16.9 inch turn there. 

[railandsail]

rrinker

On my old layout, it's a good thing I tested first. Walthers 85 foot cars would not pass one another when the inner radius was 30" and the outher was 32". I had to open the spacing on the curves to allow them to work.

So what sort of spacing between the 2 tracks would you consider a minimum,....like on a helix of say a outer radius if 31" or 32" ??

[rrinker]

I didn't go back and update the track plan, so I don't knoww aht I ended up using. There are some shots on my web site of the old layout, all the way at the bottom, where you cna see the center spacing widen out for the curves. It was enough to clear the actual rolling stock that was going to run - I tried lots of combos until I found the absolute worst case - one of them was one of those huge hi-cube cars, the wheels are well set back on those so they have a huge overhang.

 Best advice I can say is to mock it up and try it - either tack some flex with pins, or print full size if using CAD and set the cars on - I pinned down some actual track and tried various combinations of inside car overtaking the outside car and outside car overtaking the inside car, lining up the worse inside overhang with the worst outside overhang, etc. Was it an extra 1/2", for a 2.5" center spacing? Or was it an extra 3/4"? I don't remember, that was 14 years ago. I know it worked - never had an issue no matter what was run, including some Walthers cars purchased AFTER the testing was done and track in place. I'd think at 30" radius for the inner helix track I wouldn't go below 32.5" on the outer track. But agian, test it with what you intend to run. I had no locos with excessive overhang like a Big Boy or anything so i didn't test locos. The various long cars were worse on overhang than the biggest loco, a 4-8-4.

                                      --Randy

[zstripe]

railandsail

 

 

rrinker

On my old layout, it's a good thing I tested first. Walthers 85 foot cars would not pass one another when the inner radius was 30" and the outher was 32". I had to open the spacing on the curves to allow them to work.

 

 

So what sort of spacing between the 2 tracks would you consider a minimum,....like on a helix of say a outer radius if 31" or 32" ??

 

My rule of thumb and experience has been to make it wider from the get-go and not worry about ''what if". Hence 32'' outside curve, 28'' inside curve....that is center line to center line.......I have run 89ft flat cars and just about any engines on that system without issue. As a matter of fact......all the curved turnouts that I have run across are designed that way. It does not really look any different than  closer spaced curved trackwork. You then don't have to worry about it working. Two more inches is no big deal...if You want it to work always.

Take Care! 

Frank

[ricktrains4824]

Well, if my basement were able to hold anything in it other than water... Then I could go bigger than 18" radii.

However, because my basement is more dungeon than useable space, I am forced to use a small space, and, that means I am forced to use 18" radii. 

I don't have a special building just for trains, as I can't afford that. 

So, I guess all of my 6 axle units, and 60' cars should not be running on my layout at all, but they do.... Because I tweak them so they do. Long shank couplers on loco's, and I make sure the trucks swivel freely, all metal wheelsets that are free rolling, and smooth coupler swing. 

So, I make them work. I feel that this makes me a true model railroader.

But, I guess as I use sharp radii I should be a model train collector and a model trolly-er instead....

Come on guys.

Don't harp on us just because we use the space we have, just like you do, as we still put on our pants the same way you do.

After all, if "this hobby is dying" as you all like to gripe about, then you all need every single one of us 18" radii people you can get!

Without all of us sharp radii modeler's, it's no longer a mainstream hobby, but a dead one full of elitist snobs who won't be able to sustain it.

Unless one of you elitist's wants to build me, free of charge, a nice building for a real model railroaders layout with large radii curves, then I guess I am currently stuck with the sharp radii that I have now.

Ok, my rant is over now.

[ATLANTIC CENTRAL]

ricktrains4824

Well, if my basement were able to hold anything in it other than water... Then I could go bigger than 18" radii.

However, because my basement is more dungeon than useable space, I am forced to use a small space, and, that means I am forced to use 18" radii. 

I don't have a special building just for trains, as I can't afford that. 

So, I guess all of my 6 axle units, and 60' cars should not be running on my layout at all, but they do.... Because I tweak them so they do. Long shank couplers on loco's, and I make sure the trucks swivel freely, all metal wheelsets that are free rolling, and smooth coupler swing. 

So, I make them work. I feel that this makes me a true model railroader.

But, I guess as I use sharp radii I should be a model train collector and a model trolly-er instead....

Come on guys.

Don't harp on us just because we use the space we have, just like you do, as we still put on our pants the same way you do.

After all, if "this hobby is dying" as you all like to gripe about, then you all need every single one of us 18" radii people you can get!

Without all of us sharp radii modeler's, it's no longer a mainstream hobby, but a dead one full of elitist snobs who won't be able to sustain it.

Unless one of you elitist's wants to build me, free of charge, a nice building for a real model railroaders layout with large radii curves, then I guess I am currently stuck with the sharp radii that I have now.

Ok, my rant is over now.

 

Rick,

First off, if your trains are working to your satisfaction, and you are happy, that is all that matters.

BUT, if they are not working, and you ask me why, and I tell you it is because your curves are too sharp, don't blame me, or the manufacturer, or the NMRA - physics is physics.

And not everyone is willing or able to develope the skills to tinker/tweek their stuff to solve such problems.

If fact, today more than ever there is a whole group of people in this hobby who expect everything to work perfectly out of the box......including 85' passengers cars running around 18" radius.

As for your class warfare comments, well there was a time in my life when I did not have my 1000 sq ft heated and cooled train room. I wanted more, I worked hard, I paid my dues in a number of ways, trust me you can't make me feel bad about what I have. You have no idea about my path in life, or my problems, or my blessings.......

But 35 years ago when I was raising three kids in a two bedroom row house and working 70 hours a week, I knew that the given a choice, 36" radius is better than 18" radius. Heck, when I got started in this hobby at age 12, 48 years ago, I knew that 36" radius was better than 18" radius...... 

Now I have room for 36" radius, in fact I have room for 42" radius for the most part..........

Why should anyone build you anything? I earned mine, Howard Zane earned his?

As for the hobby dieing, or not, I'm not invested in that question, at 18" radius or 36" radius.

But there is no question the hobby is changing, and part of the change is a wider "gap" between modeling styles, budgets, interests, skills, and overall expectations and approaches.

It's a big tent, again, if it's working for you and you are having fun, great, but don't criticize those with bigger/different goals or higher standards.

Sheldon

[Colorado Ray]

railandsail

 

 

rrinker

On my old layout, it's a good thing I tested first. Walthers 85 foot cars would not pass one another when the inner radius was 30" and the outher was 32". I had to open the spacing on the curves to allow them to work.

 

 

So what sort of spacing between the 2 tracks would you consider a minimum,....like on a helix of say a outer radius if 31" or 32" ??

 

The NMRA Recommended Practice RP 7.2 gives 2-9/16" minimum spacing for modern standards.  Anyone doing track planning should bookmark:

https://www.nmra.org/sites/default/files/standards/sandrp/pdf/rp-7.2_curved_track_centers_july_2017.pdf

 

Since laying track to a 1/16" tolerance is difficult, I'd suggest shooting for 2-3/4" 

 

Also note this is a recommended practice, not a standard or mandatory.  I agree with Sheldon and others that advocate for using as large a radius as possible.  

 

Rick, those of you forced, or otherwise, to use substandard radius curves should not be advising others to do so as well.  What works for you might not work for them.

 

 

Ray

[Metro Red Line]

gdelmoro

Ever purchase a locomotive or 85’ passenger car advertised by the manufacturer to run on 18” curves only to find it regularly derails on 20, 24 or even 26” curves?  

Yes, that's why I left HO scale and converted to N. I never looked back.

[cuyama]

Another good complementary reference is the Layout Design SIG's Curve-Radius-Rules-of-Thumb. This distinguishes between what radii might be made to work, what will work well, and what looks good based on car length.

[mbinsewi]

Thank you Sheldon.  I don't get what Ricky's rant was about, but whats a wet basement got to do with radius?

If Ricky owns the home, then a wet basement is something he has to deal with.  It can be fixed.

Nobody was picking on him because of his layouts radius.

Mike.

[Doughless]

After reading this thread, what has struck me is that specific or unyielding modeling goals can force modelers to make a lot of compromises they don't want to make. 

If something doesn't fit, why not try to model something that does? 

Are you really not interested in older eras that used shorter cars; or logging railroads, ore haulers, or coal haulers?

I model modern era, and with generaous curves designed into my next layout, its still going to be dominated by 2 bay cement hoppers and 40 foot corn syrup tankers being pulled by GPs; eventhough I really like 72 foot centerbeam cars and SD40-2s.

I like all trains.  All eras.  I'd be happy modeling many things.  

I choose to model something that fits the space, which is why I focus on branchlines.  I will never devote the space needed for lots of mainline running, so I approach the hobby by choosing an interest that suits the space I have.  

[IRONROOSTER]

Colorado Ray

The NMRA Recommended Practice RP 7.2 gives 2-9/16" minimum spacing for modern standards.

Buried in the notes (Note 2) is that the radii are for the inner most track.  Since 31-32" is the outer track radius for railandsail you should use the next smaller radius of 26 5/8" to get a value of 2 21/32".  Widening it out to 2 3/4" will cover the classic era as well, in case there comes a desire to tun a Big Boy

Paul

[ricktrains4824]

To clear up a few things....

My rant was directed specifically at this comment. (Quote function failed last time, so trying it again.)

 

Paul3

The 18" radius crowd is a drag on the hobby.  Look, if you want to run trolley-like curves, run trolleys. 

 

This comment comes off as sounding extremely elitist, almost as if saying you are not a real model railroader unless your layout includes generous curves.

 

ATLANTIC CENTRAL

BUT, if they are not working, and you ask me why, and I tell you it is because your curves are too sharp, don't blame me, or the manufacturer, or the NMRA - physics is physics.

 

While I have the upmost respsect for you Sheldon, I somewhat disagree, to a minor extent here.

Yes, I understand that it all has to do with physics, but the manufacturer's should be putting realistic operating radii for their product, not one with "some tinkering required" instead. This would avoid most of the "why is this happening on radii X" type questions.

 

ATLANTIC CENTRAL

You have no idea about my path in life, or my problems, or my blessings.......

 

Exactly my point, which is why the "trolly" comment irks me. It comes off as assuming that we choose to have a tight radii layout, not that we are forced into it.

 

ATLANTIC CENTRAL

It's a big tent, again, if it's working for you and you are having fun, great, but don't criticize those with bigger/different goals or higher standards.

 

This was not my intent at all, and if it came across that way, I sincerely apologize, as that makes me sound just as elitist as I was complaining about.

My point, was, just because your standards allow you to have a layout with broad curves does not mean you should be putting down those with layouts that do not have broad curves, some, because there simply isn't the room too.

(And I know that you were not doing that Sheldon, but some comments on this thread certainly sounded that way.)

Trust me, I would absolutely LOVE to have the space for a bigger layout with broad curves, but it is simply not currently possible.

 

mbinsewi

Thank you Sheldon.  I don't get what Ricky's rant was about, but whats a wet basement got to do with radius?

If Ricky owns the home, then a wet basement is something he has to deal with.  It can be fixed.

Nobody was picking on him because of his layouts radius.

Mike. 

 

Mike, the basement is usually where larger home layouts are built.

Also, no, I am not the owner of the home, my parents are. However I will be helping to get it fixed if I am staying here for a while longer.

And, sorry, but the above "trolly" comment comes off as "picking on" smaller radii layout owners.

 

So, while I don't recommend anyone have a layout that includes tight radii, I also understand that sometimes, you must go with what you can, and compromises must be made and accepted.

Please know that I don't begrudge anyone who has indeed earned their way into having a large layout, my point was, don't be so dismissing of those who don't or can't.

I fully understand that some equipment will never be operational on tight radii curves, but as was mentioned, the newest modeler's often times don't. So please try to not get offended when a newer modeller asks why it don't when manufacturer X says it will. (Or when a longtime modeler rants about it not being the case.)

All that telling a new modeler to switch to trolly's for tighter radii will do, is offend them, not help them. 

Instead, try to help them understand that sometimes, you either must tinker and tweak things, or it simply will not operate.

This was what my rant was, and is, about.

 

(The quotes show prior to posting, again, so let's see what happens when I click on "Submit"....)

[joe323]

There is a difference between being able to run on 18" curves and not looking silly doing so. Perfect example I have a set of 53' Kato well cars they run on 18" curves but the overhang looks silly.  Do I run them yes very slowly as all my trains run.

[Doughless]

ricktrains4824

 

ATLANTIC CENTRAL

BUT, if they are not working, and you ask me why, and I tell you it is because your curves are too sharp, don't blame me, or the manufacturer, or the NMRA - physics is physics.

 

 

While I have the upmost respsect for you Sheldon, I somewhat disagree, to a minor extent here.

Yes, I understand that it all has to do with physics, but the manufacturer's should be putting realistic operating radii for their product, not one with "some tinkering required" instead. This would avoid most of the "why is this happening on radii X" type questions.

 

And sometimes it has nothing to do with physics.  It has to do with too prototypically accurate underbody details.

My exactrail 50 foot waffle-sided box car was obvioulsy designed to be a shelf queen.  It wouldn't negotiate a 28 inch radius curve because the wheels would rub against the underbody rigging not allowing the truck to turn sharp enough.

...unitl I removed the details.

[ricktrains4824]

Doughless

 

 

ricktrains4824

 

ATLANTIC CENTRAL

BUT, if they are not working, and you ask me why, and I tell you it is because your curves are too sharp, don't blame me, or the manufacturer, or the NMRA - physics is physics.

 

 

While I have the upmost respsect for you Sheldon, I somewhat disagree, to a minor extent here.

Yes, I understand that it all has to do with physics, but the manufacturer's should be putting realistic operating radii for their product, not one with "some tinkering required" instead. This would avoid most of the "why is this happening on radii X" type questions.

 

 

 

 

And sometimes it has nothing to do with physics.  It has to do with too prototypically accurate underbody details.

My exactrail 50 foot waffle-sided box car was obvioulsy designed to be a shelf queen.  It wouldn't negotiate a 28 inch radius curve because the wheels would rub against the underbody rigging not allowing the truck to turn sharp enough.

...unitl I removed the details.

 

Well, one could argue that it was still physics.... An object in motion tends to stay in motion..... Until it hits something unmovable.

[Doughless]

ricktrains4824

 

 

Doughless

 

 

ricktrains4824

 

ATLANTIC CENTRAL

BUT, if they are not working, and you ask me why, and I tell you it is because your curves are too sharp, don't blame me, or the manufacturer, or the NMRA - physics is physics.

 

 

While I have the upmost respsect for you Sheldon, I somewhat disagree, to a minor extent here.

Yes, I understand that it all has to do with physics, but the manufacturer's should be putting realistic operating radii for their product, not one with "some tinkering required" instead. This would avoid most of the "why is this happening on radii X" type questions.

 

 

 

 

And sometimes it has nothing to do with physics.  It has to do with too prototypically accurate underbody details.

My exactrail 50 foot waffle-sided box car was obvioulsy designed to be a shelf queen.  It wouldn't negotiate a 28 inch radius curve because the wheels would rub against the underbody rigging not allowing the truck to turn sharp enough.

...unitl I removed the details.

 

 

 

 

Well, one could argue that it was still physics.... An object in motion tends to stay in motion..... Until it hits something unmovable.

 

Touche!

[gdelmoro]

Now here are some impressive 18” curves 

https://m.youtube.com/watch?v=QeyaV_ubu7Q