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Lighter freight cars derail easier?

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Posted by 7j43k on Friday, November 9, 2018 5:18 PM

Penn Central
PS - should've mentioned these are all horn-hook couplers if that makes a difference. from the sounds of it above it may not.
 

It does make some difference.  Those couplers, because of their design, have a sideways force at each end of the car.  "Regular" couplers (Kadees and all their clones) don't.

Whether that sideways force is causing or contributing to the problem is a good question.  But if/when you change to the good stuff, it surely won't.

 

Ed

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Posted by dknelson on Friday, November 9, 2018 4:54 PM

7j43k
Lighter cars don't derail because they're light. They derail because they're surrounded by heavy stuff.

Absolutely, which is why consistent weighting is so important whether or not you follow NMRA weight standards, although some cars are SO light - I am thinking of the old 1950s Varney plastic flatcar and ore cars that were pure plastic without a bit of weight anywhere that would derail if you batted an eyelash when they went by.

Mixing body mounted with truck mounted couplers can result in sideways pressures that can lead to, or at least encourage, derailments, especially if the old hornhook couplers have springs that are so taut as to not let the coupler move in the draft gear box.

Cheap trainset cars sometimes have poorly formed wheels and axles that make derailments more likely.  Couplers with very tight springs such as some trainset cars have can also make derailments more likely.

Dave Nelson  

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Posted by 7j43k on Friday, November 9, 2018 2:59 PM

Penn Central
...ie "youre crazy or doing something wrong" types. 

 

We are, too.  It's just that we're more experienced.

So OUR crazy gets real specific and detailed.

And OUR something wrong is so specialized that most other people couldn't tell.

 

Don't worry.  If you persevere, you'll be right up there with the rest of us.

 

 

Ed

 

 

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Posted by Penn Central on Friday, November 9, 2018 2:46 PM
Awesome! being a newbie I wasn't sure what to expect on - ie "youre crazy or doing something wrong" types. LOL. Ok feel better. I'll do a few things. To the earlier suggested I'll try putting them last, see what happens. Will use various things to weigh them down, and will use the NMRA guide given to see how close I can get. PS - should've mentioned these are all horn-hook couplers if that makes a difference. from the sounds of it above it may not. thanks!
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Posted by gmpullman on Friday, November 9, 2018 2:41 PM

7j43k

And the real railroads have rules about placing light cars at the head of the train to prevent the above.

 

Ed (other)

 

I agree with you there — Just think of the dynamics of the degree of curvature, super-elevation, the grade and two or more "Snappers" (helpers) shoving hard on the rear end and — wow! 

As I recall, there was a "misstep" in placing at least a dozen, maybe more, 86 foot Trailer Train empties all in a group within that train. I'd sure like to read the investigation into that derailment. Maybe someone remembers which issue of Trains that was?

Cheers! Ed

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Posted by 7j43k on Friday, November 9, 2018 2:12 PM

And the real railroads have rules about placing light cars at the head of the train to prevent the above.

 

Ed (other)

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Posted by gmpullman on Friday, November 9, 2018 2:08 PM

The big fellows have the same problem sometimes.

I recall a Trains Magazine photo spread where a photographer caught a sequence of shots of Trailer-Train flats (empty) derailing at Horseshoe Curve. It was back in the Penn-Central days.

I think the term is "string-lining". Liken it to pulling (or pushing?) a length of string.

Regards, Ed

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Posted by 7j43k on Friday, November 9, 2018 2:02 PM

Lighter cars don't derail because they're light.

They derail because they're surrounded by heavy stuff.

I used to run a string of about 5 Superliners with absolutely no metal weights.  Just the plastic body, floor, etc.  Didn't derail.

Put a bunch of heavy cars behind them, and go through a 24" curve = flop-bot.  

 

An experiment for the OP:  we know the light cars derail.  Try putting them all at the back of the train and see if it's still doing it. 

 

All that said, your cars should all weigh approximately the same.  Light.  Heavy.  In the middle.  So, yeah, you should weight the light ones to match the heavier ones.

 

The National Model Railroad Association recommends, for HO, a weight of 1 ounce plus a half ounce for each inch of length.  Not an unreasonable weight.

 

 

Ed

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Posted by tstage on Friday, November 9, 2018 1:55 PM

Rolling stock - particular flat cars - need to be weighted to track properly.  You can always add weight on the underside of the car.  Here's a few solutions:

  • Stick-on weights
  • Pennies
  • BBs
  • Lead sheeting (A-Line)

Tom

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Lighter freight cars derail easier?
Posted by Penn Central on Friday, November 9, 2018 1:46 PM

So I have a bunch of old tyco freight cars from when I was a kid (actually thats all I have as I'm getting back into the hobby :-).  Anyway I notice the lighter ones (flatcars, tankers) derail alot compared to the heavier ones (box cars). And I'm not talking about wheels falling off poorly connected track. I mean more like they're being pulled off going around turns (24" radius) and such. 

 

It this is thing or just me? 

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