Okay, please don’t laugh at me. I have never built a layout in my life (until now). The last one I had was built for me by my father when I was 5 years old. I haven’t been a model railroader since around 8 years old. Now, I am getting back into it. Okay, here’s my problem…
I am currently building an HO layout and am having trouble with Bachmann Spectrum 2-10-2 steam engine making the curve. It is an 18" radius half circle. It will either stop dead, which at first I thought was dirty track until ran my diesel on it and my switcher and they both went through fine. Now it is making the curve, but the guide wheels either jump the rails or they rub against the steam cylinder on the side the wheels are turning towards. I noticed some loss of paint on the cylinder. I’m guessing that the 18" radius is too narrow for all of the driver wheels and guide wheels and that if I try a wider radius curve, it will be okay.
If this is the problem, and I can’t really think of anything else it could possibly be, any suggestions on what kind of curve radius I should use? I am about to make an outer perimeter track which will be of 22" radius running parrallel to the 18" radius half circle which is apparently causing the problem. Would it be wide enough for it to run across without problems? But you know, if this is the case, why not put a disclaimer somewhere in the instructions manuel that says, “This engine cannot be ran on 18” radius curves, only 22" or wider"?
As I look at the engine from underneath, the guide wheels cannot be moved any further away from the steam cylinders without getting stuck on the inside of the cow catcher, so they can’t be adjusted.
A 2-10-2 is a long rigid wheelbase locomotive. 18 inch radius curves are NOT meant for anything that stiff. It might make a 22 inch radius, but I wouldn’t put serious money on it.
Rather than spout a lot of theory and `standards,’ let me make a suggestion. Get some flex track and a piece of plywood and lay a spiral test track, starting with enough tangent to get the beast on the rails and then reducing from 36 inch radiius in 2 inch increments every 12 inches of arc. Connect power and see just how tight it can go before it leaves the rails. A few hours of construction and experimentation trumps a week of opinion and third-hand testimony.
While you’re at it, test your other rolling stock, in all possible permutations. I didn’t cast my mainline minimum radius in bronze until I was SURE that my passenger equipment could take the curves without clashing corners. The locomotives (2-8-2 and smaller) were not the problem.
Thanks, Tom. I am going to do what you suggested, but the problem is my table, where the curve is, is only 4 feet across. I hope I have enough room to accomodate the turn. I’m hoping that since she came so close to clearing the 18" radius that I can get away with 22" if not a little more of necessary. I wish someone would have told me this when I bought it, but I guess they don’t want to risk insulting a customer’s intelligence as I’m sure most model railroaders out there already know this. My dad, who has several steam engines, big ones, did not and told me that 18" radius would be enough for it. Thanks, Dad.
As usual, Chuck has given you sterling advice and information. It comes no better.
Most steamers sold are hoped to negotiate 18" curves unless the literature, or a note on the box, say otherwise. For example, the Bachmann Spectrum Decapod 2-10-0 is fine on 18" radii. But, compared to the real counterparts, a typical Decapod had small drivers that could be closer together, so a shorter wheelbase than their larger Santa Fe and Texas types, the 2-10-2 and 2-10-4’s. In fact, while Broadway Limited publishes that their Pennsy J1 Texas type needs 24" radii, our hosts found that it would squeak around 22" curves that were consistent and well laid.
This should offer you some hope that 22" will make quite a bit of difference. It still isn’t ‘great’ by any means, and certainly not generous. If you would rather construct your mains now to ensure future acquisitions will run well at track speed, such as a scale 30-50 mph, you might want to think seriously about 24". That presents a challenge in your space, surely, but not if you consider adding a 4"-6" ‘sideboard’ to your existing surface…cantilevered. Just a thought.
Ages, I mean a few years ago, it almost seemed that 18" radius was almost a standard. To get larger wheelbase engines to go around it, often one or two sets of drivers were flangeless to allow the loco to run through tight curves. This also was not uncommon on some larger 8 driver and 10 (and 12 and 14) drivered full scale locos. But for larger models, when there was interference between the lead (pilot) truck wheels and the inner corners of the cylinder casting, it was not uncommon to carefully use a jewler’s file or Dremel burr to remove enough of the corners of the cylinder to clear the wheels and flanges. With a touch of paint to match the rest of the loco color, it was rarely noticeable to most people during operation. I had to do this on a 4-6-2 I had years ago. Luckily, the valve gear hid the cuts, since the interference only occured on the rear set of pilot wheels.
Most of my locos whil run on 18", and only a couple larger steamers need 22". I even used the needle file method on steps and brake cylinder detail on a couple diesels to let most of them operate to 18" (or sharper).
Of course, some more serious modelers who have room for larger radius may not want to perform what might be termed a mutilation.
I’ve got one of those 2-10-2’s and I got one 20" radius curve going into a industrial area that is only used for switching. I tried running mine through it at a slow speed and it made it but it wasn’t happy about it. If it was going a little faster it would have derailed. The box says minimum 22".
18" radius is EXTREMELY tight radius. There are only a few real engines that could make it around a curve that sharp.
When people talk about a “minimum” radius, remember minimum is not "best’ or reccommended, it is the point at which the engine begins to fail to negoiate the curve.
A better or reccommended radius is two or three times the length of your equipment. So if you have a 16" long steamer, a better radius is somewhere in the 32-48" radius. For an 18-22" radius curve layout, 2-6-0, 2-8-0, 4-4-0 and 4-6-0’s would be better choices for engines.
My 2-9-2 has a tendency to tip and derail on any sort of a grade change. There is also that pesky loose side rod that jabs into the ground.
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My old layout has 30 and 32" radius curves, and my 4-8-4 ran great. My new layout gets down to 24" radius and while I can run the Northerns, they are very tight and only run reliably at very slow speed. No worries, I can run them on the club layout with 30" curves no problem. My normal power is 4 axle diesels which have no issues.
Could you add a 6" or more piece of table to the front or back of your layout so you could fit a 24" radius around the outside and make the 18" inside radius a 22", that way you can run the engine anywhere on the layout comfortably?
