What is the Largest HO equipment anyone as run on a 14 to 15 in radius? I have been told that most 4-axle diesels (GP-35/40) will run these small radii when the track has a good easement and the curves are banked. Is this true?
Between my modeling tests and researching old logging railroads I have seen large locomotives on hair-pin turns. e.g. On the historic Sumpter Valley Railway, the Tipton Summit had a hair-pin curve that was considered too tight for large 2-8-0’s but because the grade was well ballasted, banked, and maintained they ran large 2-8-2’s (comparable in size with K-27’s) and larger every working day.
I am asking because I do not have a lot of room and would like to make a good small layout.
The physics of model railroads are very different from real railroads. “Banking” (called superelevation on the real railroad) doesn’t help performance in the model and in fact usually makes things worse in tight curves. I’d avoid it in the layout you are planning.
Easements do help – that is, gradually increasing radius from straight track to the desired radius. But that also takes away from the amount of straight track and reduces the spots where you can add turnouts (track switches), so it’s a trade-off.
Even the tightest curves on the Sumpter Valley Railway would scale out to many inches larger than 14-15" in HO, so what works there is not a useful model guideline (not to mention that it’s narrow gauge).
The Mantua 2-6-6-2 logger is probably the largest locomotive that will typically run on 14" or 15" radius.
Decades ago, Akane and Gem imported a brass model of a Little River Logging RR 2-4-4-2 that could also run on small radius curves.
Other than that, for likely success with 14" radius curves, for steam I would stick with 2-6-0, 4-4-0, and 4 or 6 drivered switchers.
Other can and have point you at suitable diesels. As was stated, you want to limit yourself to 40ft or shorter cars, too. Some plastic open platform passenger cars (modeling 19th Century) will make 15" radius curves. But those with more detailed underbodies will likely have problems, especially on 14" radius.
Every inch of radius counts. Things that won’t make a 14" radius curve might make 15" radius. The same is true going up to 16" radius.
my thoughts, your choices
Fred W
…modeling foggy coastal Oregon, where it’s always 1900…
The Mantua/Uintah 2-6-6-2Ts (which were de-tanked and given tenders on the Sumpter Valley) can be coaxed down to a 12 inch radius. Their prototypes were designed to take a 68 degree curve - just about the same thing when scaled down.
I run a 4-truck machinery flat on 350mm (<14 inch) radius - but the couplers are mounted on the swinging bolsters, not the center car body. My other rolling stock is similar in geometry to ore jimmies or 50 ton hoppers. The longest cars I run on that radius (a couple of old passenger cars) are 205mm (8 inches) between coupler pulling faces. Anything longer is embargoed.
That said, all but the largest model railroads are squadrons of compromises flying in close formation. To model almost any main line operation without serious compression in HO, the smallest useful space would approximate a basketball court. OTOH, a logger, or a mining operation, can be realistically modeled with short cars and very flexible locomotives on tight radius curves and ‘steeper than mainline’ grades. That makes them better choices for layouts in confined or restricted spaces.
Thanks for your input. Although the conventional wisdom suggests that the smallest radii the old-time passenger cars would need at least 16 inch at the very minimum. From your post, did you mean that you had smaller idealer cars in between the coaches? Also were you using easements and if so, what is the larger part of the easements?
Any and all reflection on past experiences would be a big help.
Since I’m modeling Japanese prototype in 1:80 scale on 16.5mm gauge (aka HOj) conventional wisdom based on North American practice and prototypes in HO scale has to yield to practical experience. So far, that has been in test mode - the actual Tomikawa Tani Tetsudo (350mm curves with spiral easements, 4% grade, three helical loops, coal hauler with loads running downgrade) has yet to be built. Everything to be used on it has been run down to 300mm radius on my test spiral, but the visible rails and scenery will have to wait until three layers of Netherworld (hidden thoroughfares and staging yards) are completed. Most of that is for the Japan National Railways route with which the TTT interchanges. The JNR has a maximum 2.5% grade and 610mm (24 inch) minimum radius curves, again with spiral easements. The prototype ran through ‘vertical’ scenery, following a river that was anything but straight.
TTT passenger cars are ex-JNR (Japan National Railways) 16 meter standard design, which means their ends
Instead of looking at diesels, how about something like a Shay, which is designed for these logging railroads? If you are really going to work with very tight turns, think about the tight-turn prototype engines and cars.
Another possibility for you is narrow gauge. HOn3, I believe, runs HO-scale equipment on N-gauge track. Again, this is one of those things you’d find in logging or mining operations, but there are some examples of narrow-gauge railroads on the eastern seaboard as well.
A key question might be what do you think makes for a “good small layout” ?
From another post of yours it sounds like you want two loops on a small rectangular table. That is one way of making a small layout.
There are many other ways of making small layouts, not all of which are dependent on H0 scale engines and minimum radius.
One obvious way of getting a loop layout on a small plate without getting too tight curves is to go to N scale and do a 3 x 5 foot layout. Radius wise for your N scale trains, that is about the equivalent of a 5+ foot x 9 foot layout in H0 scale.
Another option in H0 scale is to do a layout that is not a loop. If you e.g like logging engines, you can also do a point to point shelf layout, or a shelf layout with switchbacks - as in this 2 x 8 foot Byron Henderson plan: http://www.layoutvision.com/gallery/id18.html
It is not a given that H0 scale and 14-15" radius double loops on a small plate will be the best way to make a “good small layout”.
It all depends on your definition of “small” and “good”.
You ought to consider going up to 18 inch radius curves. That is the standard minimum radius in HO. All the makers of rolling stock work really hard to insure good performance (aka stays on the track) on 18 inches. No one goes tighter. Although a fair amount of equipment will take a tighter curve, a fair amount will not. You will save your self a lot of derailments if you stick with 18 inches. You can have a pretty small layout, you only need 36 and a skosh inches of table width to do a 180 degree turn with 18 inch radius.
Chuck: Thanks for sharing findings and experiences. I took an interest in your post because you were modeling Japanese Railroads, and history tells us from the 1880’s until about the 1920’s lessons learned in the US equated into improvement in short-line railroads in Japan (and vice versa). Also I never herd of the TTT, but it sounds very impressive.
In my previous post I used the Sumpter Valley Railway (even though is/was narrow gauge) as an example because their equipment was only a few inches smaller than a lot of the standard gauge counter parts of the late 1800’s and very early 1900’s. Another reason I used the SVRy was I have personally explored original Right of Way from Larch to Whitney and the Tipton area, I was surprised by the number of really tight curves (they were extremely well engineered with huge easements) and are similar to most of the tight curves at the Georgetown Loop. I put my findings from those trips into a simple HOn3 test track and was able to run a MDC 2-8-0 at full speed around a parabolic curve with a min. radius of 12 inches (I was very impressed of how well it worked).
I know N scale would give me a larger layout, but I am just an HO kind of guy.
My plan was to build a classic double loop - single main line dual gauge HO/HOn3 layout (because HO is cheaper more available than HOn3). Space is a concern but I think I am able to get away with a 3.5 x 5 foot layout. That should give nicer curves that are 18+ inch min. radius with good size parabolic easements.
I have a small HO layout {3.5 feet by 5.1 feet} with a 15R inner loop connected to an 18R outside loop.
I had a small mike {2-8-2} from IHC that would run on the 15R but not like it. It far preferred the 18R loop.
My four axel diesel locos will run the 15R loop but again don’t really care for it, they’d rather be on teh 18R loop.
I am tearing down the layout someday and going to try to expand to a double 18R loop, as the 15 R is really useless. I would suggest you tryt o avoid the 15R loop too.
…The industry will ty to do that, especially for larger engines, but some larger engines will NOT do well on 18 inch, but my Bowser Big Boy claims it can. Smaller engines are not restricted to 18 inch, and you can buy 15 inch radius snap track. You do have to understand what is going to run and what won’t. The South Shore owned the Little Joe and had signs up “800 Class Restricted”…there were areas it could not run, but they owned smaller engines that could. Easements take the jolt away from mis-aligned couplers going into the curve.
“What is the Largest HO equipment anyone as run on a 14 to 15 in radius? I have been told that most 4-axle diesels (GP-35/40) will run these small radii when the track has a good easement and the curves are banked. Is this true?”
The only things that count here are personal experiences. What people tell you ‘should be done’ is not really relevant. The best thing you can do is to take a piece of plywood - doesn’t have to be large - and mock-up your curves and try your equipment.
I recently did just that - made a small HO standard gauge oval of code 100 track, with one ‘end’ 14 inch radius, the other ‘end’ 15 inch radius. There were no easements and no superelevation. I found the following after hours of actual runtime:
Both 40’ and 50’ cars ran easily on both curves, in any order, no derailments after an hour;
‘Thomas the Tank Engine’ locos and cars ran easily for an hour on both curves, no derailments.
An old blue-box Athearn GP-35 (4-axle) ran OK with no derailments for an hour, but it made a good bit of noisy protest on the 14-inch end.
When I say ‘no derailments after an hour’, what is meant is that after an hour I stopped that particular test; for all practical purposes, those items would run that way indefinitely, with proper maintenance.
As I say, that’s my very recent, very specific experience. Resulting decision: I’m building a small layout ‘for the grandkids’ with some 15 inch curves, but mostly 16 and 17 inch curves. An 18 inch minimum is not practical on a really ‘small’ layout which features two overlapping routes (as in G&D) and continuous running - nor is it necessary, for smaller equipment, as JA showed many decades ago.
I agree with Dick’s experience. I built many different “just for fun” 4’x4’ and 4’x5’ layouts in the past with the same success. Never went under 16" without problem with regular diesel locomotives and standard freight cars no longer than 40’. The coupling can be problematic on sidings.
Yesterday, I did a mockup test of the Erie Railroad 149th street Station in NYC on the same 4’x5’ plywood (which is about the exact size of the real yard when scaled down) and was able to reproduce 90% of the total trackage with 16" min. radius track. It worked fine and I only used Peco 244 curved turnout and trim down regular no4 turnouts.
There are quite a few sick low-radius curves on the Erie Terminal, I guess I’ll experiment with smaller radius too.
BTW, this prototype convinced me there was some way to achieve great railroading on a ridulously small place in HO. And the trackage can easily be done by some normal modelist with commercial parts.
OK, I’ve just built a mock up curve and tested quickly a few standard equipment thought it:
13-1/2" radius: 40ft box car (Athearn) were just fine and couplers worked correctly. It was possible to couple cars in the curve. I also tested it with my largest steam, an IHC 4-6-4 (their mecanism have a lot of slack) and it ran fine. The overhang of the boiler was still tolerable if you keep in mind it’s a logging operation.
Then, I build a 12-1/2" radius. Box cars didn’t couple correctly and their overhang was simply “ugly”. The loco still worked but with a lot of wheel noise.
From that quick test, I think someone wanting to run with cars up to 40’ should use 14" radius minimum. It works good and doesn’t look too bad. Using this radius, I think I can finish my Erie Terminal without buying new Peco 244 curved turnout. Real operation session will confirm if that’s a feasible idea in the long term.
A 12" radius could be thinkable for small 0-6-0T and little ore jimmies.
Keep in mind that between 18"R and 15"R you’re talking about very sharp curves vs. incredibly sharp curves…that is, even 18"R is going to limit what you can run (and what you can keep coupled together).
If you have to have a continous run layout and your space is limited, look into N or Z scale. If you really want to do HO, try streetcars as they can take very sharp curves…an O scale trolley car can do a 12"R curve!!
Of course if you don’t have to have continous run, the sky’s the limit. My current layout is the first part of a large basement-sized layout, basically and L shaped shelf layout. I’m using what will be the staging yard as a switching layout, using flats as industries along the backdrop, plus a team track and engine house. I’m using Kato track, 31"R curves and No.6 turnouts. on a layout 16" wide.