I’m definately no expert in this hobby and I have a great deal to learn, but for all you newbies out there like me here’s some advise; read, research and plan as much as you can before deciding on a layout or starting a layout. You will save a great deal of time and headaches later on as you can see below
Here’s my question:
A few years ago I started building a 4’ x 8’ layout. I decided on a standard track plan from book, bought the track and turnouts, installed the roadbed and track and found I didn’t like the plan. The layout was based on an 18" minimum radius. Now I’m abandoning this layout and designing a new layout based on my prototype (Montana Rail Link), room size and layout and specific industries/scenary I would like to model. What I finding is that my room size and layout is condusive to an 18 minimum radius. Also, I could reuse the turnouts and track I previously purchased. However, I’ve read that I need a 24" radius to run six axle diesels. Is it still possible to run the six axle diesels on the 18" radius?
Can’t be certain of this, but I believe most six axle diesels will track on an 18" radius curve. The real question is will it look right and if you are to run any passenger cars on it will they track. They have a longer overhang and will have trouble coupling to a shorter overhang car. Bob T
Anyone who tells you that six axle diesels won’t take an 18" radius curve is either a liar or doesn’t know what he’s talking about. I run plenty of big six axle jobs on my layout and every curve on it is 18" radius. I run an SD9, SD40, SD40-2’s, E6’s, E7’s, PA’s, even a pair of huge SDP40F’s. I was even running an AC4400 for a while before I stripped it to rebuild one of the SDP40F’s. Sometimes I run my biggest steamer, a 2-10-2.
Most anything RTR these days is made to work on 18" radius curves, even if it looks silly doing so. However you will have probklems with long cars and locos if the couplers are mounted to the bodies - on sharp curves they will be offset so far to the outside that they can push trailing cars right off the track.
You mentioned building in a 4x8 space - you cannot use 24" radius cuves on a 4 foot wide layout. The 24" radius is measured fromt he center of the track, so the outside edge is more than 24" in radius, which menas more than 4’ in diameter. You can use 22" radius curves on a 4’ wide layout though. It’s close to the edge though.
Some six axle diesels will not run well on 18" radius turns and some will. Best thing to do is refer to the manufacturers manual or data sheet. For instance if you look at the broadway limited site for the SD40-2 you will find that the minimum radius is 18"
I don’t think you’ll have trouble with 6 Axel locos as much as you’ll have trouble with full length passenger cars. At least that’s what I’ve found.
But all the guys who say you MUST have at least 24" radius for a realistic “look” apparently have a bigger basement than I do. it is HARD to achieve much in the way of an interesting layout when you decide your min. will be 24" That’s why we wind up with 18"… you can do so much more with the layout that way. Sure 24" would look nicer. But it’s a trade off, and I opted for the more interesting layout with tighter curves.
So did I. I have a room that’s 8’ x 13’. The layout is roughly 8’ by 10’ and shares the room with a refrigerator, kitchen counter and sink. The heater and computer are under the layout.
I think I would go for at least a minimum of 22’’ radius curve, that is what I plan on my layout, while I’m on the subject of my layout would 22’’ radius curve work on a 4x8?
If appearance is the only concern, it should be possible to use 24" radius curves on the front of the layout and 18" curves for the rear of the layout and still fit on a 4 x 8. The rear curves could be obscured by scenery and buildings, etc.
I’ve never tried this nor have I even heard of anyone doing it, but I might give it a go on my next layout.
The best recommendation I can offer is to test anything before you commit to it if possible.
Nice attitude JW. All I have to do is give you ONE example of a 6 axle unit that wont take 18" radius curves. In fact, I have an OMI SD40-2 that doesnt run on anything less than 24". Also, SD40-2s with couplers that are in their proper position (and not 6’ too long) will NOT go around 18" radius curves. So you are correct and wrong at the same time.
For the OP, I use the 3x rule. Look at 18" radius. The 3xs rule means that anything 6" and under will run reliably on those curves. 24" will allow you to run 8" and so on.
Now, that doesnt mean they wont track around 18" radius curves if they are 8" long, it means that other issues will creap up and compromises will have to be made. Also, they just look stupid and toy-like to run something like an SD40-2 on 18" radius curves (that is my opinion).
I’m sure JW didn’t mean all of them would, but I think he’s right that most of them will. And to most people they look fine and not at all stupid and toy like.
I had a layout with 15" curves (but no six axle engines) and everybody said it looked great.
My layout is intended for fun. I am not trying to duplicate anything in the real world. I also did not do enough research on things before starting and I have redone a couple spots.
I had a couple Atlas snap switches back to back in one spot that essentially made as “S” curve and that kept causing derailments. I have a GP-38 (4 axle) and a SD-50 (6 axle). The GP-38 normally worked fine, but the SD-50 had the issues. I ended up swapping out a few of my couplers with the “long shank” variety and that resolved the issue of the cars transiting that S-curve. Since then, I reconfigured that set of switches to eliminate the S-curve and now use No 4 turnouts there, so it is even better now.
On the regular 18" curves, my SD-50 did not have any troubles even before I swapped the couplers on a few box cars. It was only 2 places that I created “S-Curves” that had issues. In the 2nd location, I had enough room to put in about 10" of straight track to break the S-curve up a little.
I am only talking about the trains staying on track. I am not worried about how realistic they look. My layout is for my son and I to have some fun, not about being prototypical. Thomas the Tank Engine has the most miles on my layout so far.
HO equipment makers will go to any length to allow their product to run on 18" radius, since that is the “train set standard radius”, and there are a lot of train set layouts out there. They can sell a lot more units if it can run on 18". In the rare case that the maker says his product needs more than 18" radius, it’s best to believe the maker. Most equipment just doesn’t say anything about minimum radius, in which case I assume it will work on 18" curves.
In the doubtful cases (whacking long locomotive with no minimum radius) try asking the hobby shop if you can return the unit for credit if it turns out to be too long for your layout.
The sharper the the curve, the more track can be squeezed onto the layout. Was it me, I’d work hard to get 22 or 24 inch minimum radius on the main line so I could run passenger cars and big locomotives. Model railroads are a tradoff. You have to decide what you care about most. You can have a fine layout with 18" curves at the cost of being unable to run long equipment. You can have an equally fine layout that has less track but runs the big stuff. It’s a personal decision.
Cat, welcome to the wonderful world of Lack Of Room. Plus there is more to lack of room than you think! I for now have a large room and do have some 24 inch turns. Now 24 + 24 is 48 inch’s plus say 4 inch on each side for clearness. That is 56 inches or 4.6 feet. If it is against a wall it is all most impossible to do any modeling, plus if there is going to be a derailment it will be in that conner! Last night a Rio Grand coal train rammed the back of a Santa Fe passenger train! It was a nasty mess, guess where it was, yep at the deep end of the bench. So up I climbed onto the bench to retrieve the cars.
I have been in this hobby for only 3 years at first all I cared about was the train stayed on the track and 18 inch turns where fine with me. Goofy looking was fine if it tracked well. As stated big engines can take 18 inch turns (noted, some will not but if you look it up at the manufactures web site it will be stated what sizes turn it will take) even my PCM Big Boy 4-8-8-4 and Y6b 2-6-6-2 steam engines will make the tight 18 turn I have left.
But, as you do this more the picker you will become. I know I have and stopped running my long tank cars they are 9.25 inches long and do not look right on 22 inch turns.
Now that you think all is lost, take a look at this.
I am in the middle of planing my new layout and it will be a donut design. You have the best of booth worlds.
Ideal withe for modeling is under 36 inches or less, you can do that w
You can probably run most six axle diesels on 18" radius curves, but you are pushing the limits real hard. The simple fact is, the wider the radius, the better your trains will run. Trains that derail a lot are no fun.
If you can squeeze out a 5 X 8 or 6 X 8 in the available space, by all means do it. That way you can broaden out the curves to 24"-26". If you are using flex track, I advise you to include spiral easements leading into the curves and the curved portion of your turnouts
I’d second going for 22" if you can. I have 22" on my test 4x8’ layout, and have found that while passenger cars run without problem, even at that radius they overhang a lot. Enough to spoil the visual effect for me. My Atlas RS11’s and GP9s also will not recouple on the curves, as they have normal length couple shanks.
Just food for thought. Ken has a pretty decent looking idea there.
Wow. I have really only been doing this for a few months and have already gotten a compliment on an idea.
I am not sure if I had read about using the longer shank couplers anywhere or if it was an original idea. When I kept having derailments at that pair of switches I finally noticed how sharply the rear of the SD-50 and it’s coupler shifted at the moment the car behind it would get derailed. That’s when I thougth a longer shank on the front of the box car or one that had a truck mounted coupler would help it negotiate that turn.
The extra length couple doesn’t stand out that much to me. The rest of my rolling stock did not have issues with the S-curves, only the car just behind the SD-50. So, I only really needed to modify the front end of what ever car would be behind the SD-50 (or the coupler on the engine), while the rest could retain the “normal” couplers.
That was the easy solution (compromise) for me until I redid that section of track.
