What’s the minimum radius for one on zero grade?
As in, if I made a shelf layout with return loops at both ends, what minimum radius would I need.
I know 30 inches would be nice, etc., but what would work. I don’t have to couple on the curve either.
I believe Joe Fugate said the radius should be 5 times the car length for coupling & uncoupling. How about if you don’t need to couple and uncouple?
i would think anything over 26" would be good, you might get away with 24"
it depends which autorack, what is coupled to it, and how good your track it.
For reliable operation, not much under 30" is going to work in HO.
Looking at the details:
Now, lets say there is only a small amount of play in the couplers, like body mounted #5’s, and you try to use a small switcher to pull or push it around the curve - the car will derail. But if you use something like a D8-40C, it will be okay, because the big locomotive has about the same overhang as the autorack.
My “test loop” track has 32" radius curves. The autoracks run fine coupled to anything I have tried so far, both forward and backward. However, asthetically, they look terrible, the outside rail of the track is far outside the vertical line of the body as the car runs through the curve. To look “natural”, I am guessing the radius would need to be 36" or larger, haven’t had the opportunity to test on larger radius curves yet.
My Walther’s HO auto racks can make it around a 22" loop, but they look terrible.
I thought I’d revive this thread, since there’s another thread going on about minimum radii.
I’m really hoping to get away with 22" return loops on a shelf layout design.
Does anyone else have any experience getting autoracks around 22" curves - as ugly as they may look?
I’d say no less than a 36" radius considering the length of the car, otherwise any long cars would tend to either derail ,uncouple, or both.
Nice topic… I have 5 Walthers Autorack’s my self and I am working on the same questions… I laid out a test track on the carpet to get some quick and dirty answers. I used 22" sectional Track from Atlas. The cars were able to go around, it appeard that in some case that the corners touched each other but it was hard to tell from my angle, plus the track may have dipped in on the inside of the curve. An earlier post says he was able to have them work @ 22". I will say that this is the smallest you will able to go if at all. There was quite a bit of over hang when they went around, but i have to say it was nice to see them roll. They are one of the more unique rolling stock…
Well… That’s my 2 cents.
If you are talking an auto-max you are looking at 24’’ as a minimum but they will indeed not look good, regular autoracks im not sure about though.
I’m thinking another factor will be what they’re coupled to. Probably the longer the diesel, the better.
Darnit, I bet they wouldn’t work coupled to, say, a 50ft boxcar on a 22" radius.
I’m trying to work out a shelf design, with an unscenicked return loop just to “turn the train around”, and have the smallest radius possible to do so.
I just read Joe F’s link of preferred radius http://ldsig.org/wiki/index.php/Curve_radius_rule-of-thumb
and frankly, it’s got me pretty worried about trying to get away with a 22" radius.
N-scale anyone?
CARRfan
I’ve studied the LDISG Rule curve radius rule of thumb and the NMRA’s RP on curve radius. Both are valid to a point. The rule of thumb tends to be more useful, because it deals with mechanics of cars on curves instead of just appearance. Appearance alone is just too subjective when you are trying to make the most use of your space!
Remember, the 3x rule of thumb is used for reliable tracking with body-mounted couplers on car lengths up to 1/3 the radius. The 3X rule seems to work for reasonably weighted cars in long trains on helii. In another words, if you stick with the 3X minimum radius, curve radius will not be the cause of your derailments.
Lionel and other 3 rail O often operate on curves that are only 1.3X the length of the longest car, and pretty reliably as well. What is different? 1) truck mounted couplers 2) cars are coupled at a considerable distance apart 3) loose tolerance on couplers so they won’t bind if not meeting straight on 4) little-to-no underbody detail to hinder rotation of trucks 5) bodies mounted higher than prototypical to give additional clearance 6) trucks spaced closer than prototypical to ends of cars, especially on longer cars. A long train is 10 cars, and string-lining is not unusual on the sharpest curves with long trains if any of the cars are particularly light.
I have kept note of what has worked and not worked on my own and my father’s layouts, and track the reports of others on the various forums with respect to radius becasue it interests the engineer in me. I have concluded that most of the time reliable operation at 2.5X without any modifications is achieveable as long as length of cars and locomotives is reasonably uniform. I would not want to push this hard in a difficult-to-access helix though.
To push curve radius to 2X the longest car length does generally require truck mounted couplers on the l
Hey, Fred, those are some great observations … can I post them as a note/comment to the LDSIG Wiki curve rule of thumb and attribute it to Fred Wright?
You can see what I have in mind here … if you don’t like it, I’ll delete it. Please say yes, I think people will really appreciate your insightful comments.
Joe
Please go ahead. I’ve been meaning to join the LDSIG - another thing on my round tuit list 
I appreciate the great work you guys have done. I almost fell over when I first discovered the radius rules of thumb a few months ago - here was an obvious reasonably objective way to relate car length to minimum radius. My hat’s off to the group.
Fred
I was able to place an 89" Accurail flatcar on a 33.5" radius curve Bachmann E-Z Track without any part of the car riding over the edges of the roadbed. If you attempt to use the smaller raidii (down to 22" radius curve, make sure you use transition curves, even if it is a hidden loop, to avoid decoupling.
Big, real BIG. [}:)]
Tilden
Alright guys,
The information presented has been very helpful.
I really, really want continuous running on my next layout, and I want to run the “big stuff”. I currently think I’ll have a 2.5ft wide by 9ft long shelf, with the ends connected by a removable oval with 36" radii on the ends. (This will fit into my 17ft long garage).
The darn real railroads are screwing up us modeling guys by making thier equipment longer and longer. If it gets any longer, there may be a resurgance of TT scale!