banking of turns for very long trains?


M

mikeb2008

Member
So, I put together my HO layout, and I'm a newbie to this, so bear with me... I find that pulling maybe 40 or so cars is a big problem. Not because the loco can't pull it, but because going around the turns, the "tug" of pulling all those cars tends to make them want to topple over to the INSIDE of the turn. What's rather funny (but not surprising I suppose, due to the forces involved) is that if you have plenty of speed, they are less likely to topple over. So this makes we wonder: Should the track be banked in the turns, to the OUTSIDE of the turn? (Which would be contrary to "common sense"). For those of you interested in seeing the layout in its very rough form now, I have a youtube video. It's really silly, but you can at least see the radiuses I am dealing with: youtube video
 
More than likely its the weight of the cars thats causing you problems. If the cars dont weigh enough, then they will fall over on the inside of the curves.:cool:
 
I agree w/ThoroughBreed. If you have lite weight cars in the middle of your train, then the heavy cars will start derailing the lite cars in the middle. I add weights to all my cars. The way I test a bunch of cars is backing them up & U will find all the underweight cars will derail even in a straight run.
I've tried banking turns just for looks, but always have trouble w/cars w/a high center of weight will topple over. Like flat car loads that are tall.

Larry
 
Good advice. Check the NMRA web site for the correct weight for cars of various types and lengths and make sure your cars weigh at least that much. It will help those long trains stay on the curves. BTW, real railroads do make banked turns, called superelevation, to help trains stay on the track on long curves but the curve is banked towards the inside of the curve, not the outside. Centrifugal force helps the train stay upright at speed.
 
think of the banked curves on real railroads like the banked curves on car racetracks.
 
If you don't want to add weights to the cars, just try putting the heavier ones in the front. If you have any metal rolling stock, put those to the far front. Also a low radius turn will also contribute to the problem. If you're under 18 inches the cars will start to hang and pull over.
 
Also check that your trucks aren't too loose, one should be "snugish" and one should be free to wobble slightly. Then check that your wheelsets roll freely and the axles aren't too tight. But I agree with the weight thing.
This plus the above comments should keep you on the rails.
 
I agree with Ham......while adding weight to your cars MIGHT help, it may not be enough by itself. A good rule of thumb is to put the heavy cars to the front and work back to the lightest cars. Long cars will cause lots of problems also, as will tall high centered cars......you want problems, try putting some autoracks into your mix...you get tall and long in one car. Also check your trucks and make sure they roll freely...you'd be amazed how many problems a sticky truck can cause if it's towards the rear of the train.
 
Good advice here. As an addition, it might interest the originator to know that there is a formal name for the phenomenon..."stringlining". It happens in long consists, even in the real world in the right conditions. You will have a very tough time getting this fixed if you insist on long trains and substantial amounts of curvature tighter than radii of about 36". The reason is that, as you weight cars to the extent they stay railed, you also place excessive demands on the gears in the final drives of your engines...unless you don't mind them spinning in place and leaving your engines weighted as they are.

IOW, you can't have your cake and eat it, too...not in HO. Weighting cars sufficiently to minimize stringlining in long trains means adding motive power, which ups the cost of your hobby.

It's worse on grades.

-Crandell
 
Thanks to everyone for all the advice. I'm going to have to try all the suggestions here. All of my rolling stock is second hand, so their condition varies a bit. Looks like I'm going to have to spend time with each car and get it into "tune". I am still thinking that any banking into the turn would worsen the stringlining problem, unless my speed is sufficient to have the centripetal acceleration cancel out the bank. So, at the very least, I think I should make sure I have zero bank in the turns. Any comments on that concept? Again, I know I have to tune up and properly weight each of these cars to get them running well... If it continues to be a problem I want to have a plan b.
 
Mike, if it continues to be a problem after you've got all the cars weighted correctly and have the trucks so they are both free rolling and have done the "tight-loose" thing, the next thing to look at is couplers and track. Are you using Kadee knuckle type couplers? If not, you must be using the big black plastic types, commonly called "X2F". These are notorious for exerting side forces on long trains and derailing in curves. If you have the X2F types, changing them to Kadee's should be your next step.

If you already have Kadee's, the next thing to check is how well the track is laid on the curve. If there are any kinks, even small ones, they will show up with a long train ad cause derailments. You can sight down the track with your head right above the track surface and see small kinks. You can also feel them if you run a finger along the curve, once for each rail. Long trains demand perfect trackwork so that's the usual suspect if everything else seem right. The curve should indeed be level compared to the underlying surface. A carpenter's level will tell you if you have a problem with a hump or dip somewhere.
 
Progress!

I spent hours fiddling with my cars, and have a bunch of them running really well now. Thanks for the tips guys - The tight/loose thing and the proper weighting made a big difference. Here's a video (again silly, sorry, I can't help it) of 3 low cost Bachmann SD38/40 diesels pulling 43 cars:
http://www.youtube.com/watch?v=lEi_IUDZlBo
Also making an appearance is my Athearn BigBoy which can easily handle the 43 cars by itself too. When I get more of my cars "fixed", I'll see how many more I can move, but for now, I think this is great, for the size of my layout.
 
Cool video, Mike. I see you have kind of mini Tehacahpi loop there. Looks like you've got engines and cars running pretty well. I can see that some of the cars are old Tyco and AHM cars that you'll probably not want to keep once you get further into the hobby but it looks like you've picked up some nice Athearn cars as well. You've made a good start.
 
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