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6 axle diesels and tight curves

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  • Member since
    March 2008
  • From: O'Fallon, MO
  • 96 posts
Posted by kbaker329 on Friday, October 3, 2008 1:09 PM

Thanks again to all for the advice and information.  It looks like I have some work to do as far as checking trackwork and my engines.  If I can make it work, I'll definitely post the results.  I just can't give up on seeing high nosed N&W SD45's running long nose forward pulling a coal train!

Thanks again, Keith Baker

HO scale modeling N&W and Union Pacific, somewhere in Missouri between 1940 & 1990!
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  • From: Elmwood Park, NJ
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Posted by trainfan1221 on Friday, October 3, 2008 2:14 PM
Keith, In case it wasn't mentioned already, try to have one of those NMRA track and wheel gauge things.  They are good to make sure everything is the right spacing and it could help with the tighter curves.  Just a suggestion, but I have managed to operate some larger equipment on some pretty small curves in the past.  Yeah it didn't always look the best but it worked.  Good luck.
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  • From: Spanaway, WA
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Posted by SMassey on Friday, October 3, 2008 3:50 PM

I ran into a problem once apon a time ago with a couple of Athearn Locos I had.  I tried checking the guage and it was fine, I still derailed.  What I found was the side frames on the trucks were not allowing enough side play on the wheels.  After moving the truck sideframes out a little the problem went away and my Sd40-2s and an SD60 could negotiate an 18"R curve with no problems.  I did find a problem with the Genisis SD70MAC, the loco itself would make the 18s just fine but the couplers would not deflect enough and it would throw the first car behind it off the tracks.  I didnt fix this issue but I figured if I shaved some of the plastic out of the sides of the coupler box (part outside the loco's body, if you own one you will know where I am talking).  I sold the Genisis in favor of the same loco made by Kato. 

 

I have never had an issue with my Atlas 6 axle locos on tight curves.  I cant help you with those,  I know that good trackwork will prevail over any modification you do to your locos.  If you find that ALL of your 6 axle locos derail in the same exact spot then that is more likely a track issue over a loco issue. 

 

Hope this helps you.

 

A Veteran, whether active duty, retired, national guard, or reserve, is someone who, at one point in his or her life, wrote a blank check made payable to "The United States of America" for an amount of "up to and including my life."

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Posted by mlehman on Friday, October 3, 2008 4:41 PM

Keith,

I think GMTracing has a point here. The transition between level track and the grade that he's talking about is called the vertical curve. Especially when a sharp transition to the grade is combined with sharp horizontal curves, you can run into the intermittent derailment issues you seem to have.

It's as much about long wheelbase on both the chassis and the the three-axle trucks as anything. This will be much harder to cure than going around small radius horizontal curves. If you can get some more front to back rocking in the the connection at the king pin on each truck, that may help.That will help some with long wheelbase trucks. It's awful hard to change the wheelbase between truck king pins on a model, though.

Mike Lehman

Urbana, IL

  • Member since
    July 2006
  • From: Miltonfreewater, Or
  • 284 posts
Posted by RRTrainman on Friday, October 3, 2008 8:23 PM
All of my 6 wheeler's run fine on 18"r turns.  Sometime your curve is to sharp for it tostart into the curve.  I run a transitional curve first before I run the actual curve.  Start with a 22"r curve and transit to a 18"r curve.  This help set up the trucks on the curve so it prevents derail on the main part of the curve.  Even my articulated steam locos run fine.  If you are going straight onto a cuvre like 18"r the trucks sometime run off because they don't have time to react to the cuvre in time. I hope this helps.

4x8 are fun too!!! RussellRail

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  • From: New Joizey
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Posted by SteamFreak on Saturday, October 4, 2008 8:31 AM

Keith,

You're getting (mostly Whistling [:-^]) good suggestions here.

While gauging and checking for interference, another thing to check is that the trucks are level. You can set the loco on a pane of glass and inspect the wheels to make sure that all 12 are in contact with the glass at the same time. It is possible for a truck to be slightly warped, or a burr or other manufacturing defect to cause a wheel or wheelset to ride higher or lower than the rest so that the truck will rock a bit. It sounds like the front wheels on the front truck are derailing, if I read you correctly. If the middle axle is lower than it should be, or the front axle higher, then the front wheels will tend to derail on curves.

Good luck, and let us know what you find.

  • Member since
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  • From: Pacific Northwest
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Posted by Don Gibson on Saturday, October 4, 2008 12:08 PM
 kbaker329 wrote:

I was looking for responses from people with ideas or who had tried something that actually worked for my situation.  If there aren't any, then fine.  But if there are, I didn't want them buried underneath simplistic responses like, say, yours, for instance. - Keith Baker

ADVICE: I don't think getting 'snippy' with 'Midnight Railroader' or anyone else, is helpful;

YOU have the problem. YOU chose your equipment. YOU choose to NOT change your radius,  - not he.   YOU asked for options.

(YOU got them). Now, go do the right thing.                            

Don Gibson .............. ________ _______ I I__()____||__| ||||| I / I ((|__|----------| | |||||||||| I ______ I // o--O O O O-----o o OO-------OO ###########################
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Posted by Autobus Prime on Saturday, October 4, 2008 1:24 PM
 Don Gibson wrote:
 kbaker329 wrote:

I was looking for responses from people with ideas or who had tried something that actually worked for my situation.  If there aren't any, then fine.  But if there are, I didn't want them buried underneath simplistic responses like, say, yours, for instance. - Keith Baker

ADVICE: I don't think getting 'snippy' with 'Midnight Railroader' or anyone else, is helpful;

YOU have the problem. YOU chose your equipment. YOU choose to NOT change your radius, (too much work?) - not he.    

Now, go do the right thing.



DG:

I don't want to be rude or start a fight, but I think something should be pointed out, because of the way threads work. This was the original post (boldface mine):


I have a question concerning 6 axle diesels and curves under 22" radius. Most of my Atlas engines and a few of my Athearns handle 18" with no problems. However, a few others like my new Athearn N&W SD45 and my Southern SD40-2, don't. Has anybody modified a 6 axle diesel to work better on tight curves, i.e. modifying the trucks to allow more slop, allowing the truck to swing more, etc. I'm looking for ideas to try. And please, before the bandwagon starts rolling, I know 6 axle diesels look and run better on curves greater than 22-26 inches of radius, but my layout isn't going to be changed anytime soon, so that's what I've got. I can live with the overhang but not with the derailments! Thanks for any info.


The OP made it clear he looking for ideas, not ideals.

 Currently president of: a slowly upgrading trainset fleet o'doom.

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