I have 18’‘R turns on my layout. I am looking to expand my steam collection (HO Scale) with some larger locomotives, but am worried about the consequences of running more drivers on such tight curves. Most locomotives I am looking at have a recomended minimum radius of 22’'.
Can any damge be done to the locomotive by running on tight curves?
If you can get a locomotive recommended for 22" curves to operate on 18", I don’t believe the locomotive will be damaged as a consequence.
The manufacturer is suggesting that it WON’T operate on 18". As in it will not fit.
Ed
Won’t damage the loco, but in all likelyhood loco will derail. You might get lucky with a specific loco but generally larger locos will not run reliably on smaller radius.
One more point - sometimes an engine can run on a low radius, but when you couple cars behind that engine, the overhang derails the coupled cars – or derails certain cars. The minimum radius that is mentioned in product reviews or advertisements does not always take that into account.
Dave Nelson
Running a locomotive on a too tight curve could result in a derailment. Or depending on the speed it could turn over (if near the edge it could end up on the floor) which might damage some of the detail.
Since 18" is popular in HO, manufacturer’s generally try to make their locomotives run on it. When they can’t and advertise it at 22", you probably will have problems at 18". Running it very slow might keep it on the track.
Enjoy
Paul
Not to worry about damage to locomotive. The issue is derailment. If the maker puts “22 inch radius” right on the packaging, you can be pretty sure the locomotive will derail on 18 inch curves. Maker’s go to a lot of trouble to get their product to handle 18 inches, since that is the standard radius in train sets. When engineering fails to squeeze the locomotive around and 18 inch curve, marketing reluctantly allows the “22 inch radius” mark on the packaging to reduce the amount of product returned by customers for derailment.
If the package says “22 inch radius” it is best to believe it.
Over a long time, I suppose it’s possible it could affect the driving wheels negatively. I have a BLI 2-10-4 with 24" recommended min radius. In tests I could get it go around a 22" radius curve, but the wheels squeal pretty bad. I imagine over time that could cause wear and tear on the wheels.
If your layout space only allows for 18"R HO curves, you’d be best to stick with smaller engines - 0-6-0 switcher, geared steam, etc.
A large engine might take the curve, but will look silly doing so. And silly looking trains is not what this hobby is about.
What will happen?
Hundreds of voices will cry out in 1/87th volume as your train derails and plummets onto the ground.[:o)]
I’d be more concerned about damage to the layout, as in when you tear up the tracks to rebuild it.[swg][(-D]
My concern is that you will spend money on the big steam locomotives and they will end up as shelf queens because you can’t run them successfully.
Dave
I can tell you with confidence that ain’t no steamer engineered for a 22" radius that will stay in the rails on an 18" radius curve. No way, no how. Those 4" represent an out-of-spec underage of 18.2%, or about 20% in easy figures.
I can think of the extra friction on the linkages outside the drivers (even assuming the rods don’t scrape the flanges), the extra wear on the brass bearings, God-knows-what happening at the wipers, more flange wear (a LOT more flange wear) inside the rail head, and the potential for shorts with metal frame components or cylinders (bad news for decoders potentially). I could even see some scraped-bare painted sections.
A responder already mentioned overhang and coupling problems. Yewbetcha. As an example only related to coupler problems, will you have to drill another hole in the draw bar under the steamer’s cab so that the tender trails sufficiently further back to keep its forward bulkhead corners or grabs from snagging on the cab? I’d lay a few coins down for that one.
-Crandell
Another thing to be aware of, is what company is suggesting the minimum radius. For example, the Bachmann Acela Express has a 22" radius as a suggested minimum, but I’ve managed to run the train around flat 18" curves. I wouldn’t recomend it, but I could.
On the flip side, Walthers’ passenger cars have a suggested minimum radius of 24", but I’ve heard that they really need 26" minimum curves to run reliably.
Bowser and Mantua 4-8-4 and 2-8-2 engines used blind center drivers so 18" radius could be run all day. Best bet is to go with the manufactuers recommendation.
Our prototypes (and this modeler) routinely embargo certain routes to certain rolling stock - for a variety of reasons, substandard curvature being one of them.
The solutions available are:
Why 24 and not 22? Two reasons:
Do I practice what I preach? My mainline has 24 inch radius (and larger) curves, while my shortline wraps itself around curves tighter than 14 inches. At that, all the rolling stock cleared onto the Tomikawa Tani Tetsudo (including a couple of articulated locos and a four truck machinery flat) have been test run down to less than 12 inch radius.
Obviously, my larger locomotives and longer cars are never sent up the hill on rails surveyed by chasing a mountain goat up the valley. They still have lots of roaming room on my visible mainline and in the netherworld of hidden staging yards and thoroughfares.
As for the prototype, if you follow the UP through Wyoming by satellite, you’ll see lots of places where curves were widened and wiggles were straightened, changes made possible by modern earthmovers and made necessary by the purchase of Big Boys.
Chuck (Modeling Central Japan in September, 1964)
You HAD to know this was coming:
I got my Tenshodo GN S-1 4-8-4 to go around 18" radius curves–it was specced for 22". I filed the hole in the drawbar to allow it. But it happened.
Yeah, it looked like an Irish Wolfhound stuck in a dog carrier. REALLY REALLY sad.
And it DID NOT derail while doing it.
Will it ever happen again? No, never.
Ed
I remember a review of a model loco where the reviewer complained of the unprotypical blind drivers. Turned out the reviewer was wrong. The prototype had bilnd drivers.
I have two Athearn Genesis SD70ACe. They has a minimum radius of 18", and a recommended radius of 22". I run them on 18" radius curves, but they really overhang ( you can see the outer rail sticking out from under the fuel tank, and one has a habit of tilting cars in the entrances to the corners, or just derailing them. They do run on 18", but for no worries it would be best to go with 22".
Considering the slight problem with the SD70ACe, I wouldn’t think about running large steam on 18" radius. Remember, when it comes to the curves on your layout, bigger is always better.
The old 18 inch curves are still here to haunt us, probably due in part to the 4x8 sheet of plywood and what will fit on it - 18 and 22 inch curves.
This comes up time and again, and modelers end up finding out how hamstrung they are by tight modular track curves.
[preach] So even if space is tight, break free of the straight jacket and get curves which are nominally larger, such as 24 inch curves or larger. It only take a little more space and you can run so much more and have a smile on your face. KATO Unitrack in HO offers modular track in a wide variety of cuves so YES, you can do it! You’ll be glad you did.
As others have noted, running trains on radii will not damage them, they will more than likely derail so if they fall off the layout, thats the only damage that will occur.[/preach]
Curves are like computer specifications. When Microsoft says it will run with 4 GB of RAM, what they did not tell you is that you should have a minimum of 8 GB RAM.
Thus it is with locomotive curves: If they say it will work on 22" radius what they really mean is it would work (and look) much better on 26" or 30" radius curves.
On Route of LION him cut tables with 24" radius edges, the plan being that the curves would have to be much bigger, like 26, 28, 30, and 32 for the four track mane lion of him. TRUF IS some of those curves are way to tight for 85’ cars but fortunately subway cars of LION are all 50’ long and can take any corner I can throw at them.
If you must renovate your layout to accommodate a larger locomotive, you would be wise to go all the way making 24" your minimum and 26 ot 30 your standard. After all, this will not be the only locomotive that you will buy and LION does have som 85’ cars that cannot ever run on a 32" radius. That is to say, he has never run them, but they look great parked in the staton.
Computer of LION has 32 GB RAM.
ROAR
Sound advice which translates into the trainworld. In general, you should expect some disappointment if you are going with recommended minimum radius as well as minimum recommended memory. (btw, Windows 7 64 bit recommended minimum is 2 Gb, I’m running on 4 Gb quite happily - I’m on a tight budget too)