Cutting down on String Effect

Model Railroader General Discussion (Model Railroader)
1

I have some idea on how to do this but still a little foggie on how to get the most out of my track and trains.

First what I know.

1 Larger turns help, 22" is better than 18".

2 Make your rolling stock roll as easly as you can.

3 Avoid grades, make the effect worse.

What I have at this point.

1 Still have 18" turns.

2 Track has around 2 degree grade and not what I was trying for.

3 Rolling stock manily Cheap LL and Tyco but 70% have been up grade and roll about the same as my Atherans.

4 Power is not a problem, doubled (spell check) or triple headed E-6’s Protos.

So far the max I have hauled is 36 cars, but then in the 18" turns string effect happens and on there sides they go.[xx(]

I know get rid of the 18" turns and the grade and up grade all the cars.

With what I have here are a few missed spelled questions.

1 Should the easyer rolling stock be in the front or rear of the train?

2 Will the lenght of the rolling stock effect the stringing effect? In other words should the shorter car be toward the front or the rear of the train?

My goal is 40 to 50 cars. I did make a few laps with 40, but then the shorter cars fell off in a 18 turn.

Thank You for the answers that are coming.

Cuda Ken

2

I don’t run trains long enough, nor is my history long enough, to have encountered this problem. Your questions are interesting, though, so I will give what I hope is an educated guess and see if the more knowledgeable members agree.

First, get rid of the cur…oh, you already said that.

Since the effect is caused by tension on either side of the tumbling cars, I would guess that it doesn’t much matter where the better rolling ones are. It could be that the pulling engine in front of the offending cars is not contributing to their tumble, and that only those behind them are doing it, but it doesn’t make sense to me… both the front and rear of those cars are getting lateral forces imparted to them, although one may be less than the other. It would be useful to identify and label all the good cars, place them behind the ones that tumble, and see if the tumbling stops. My guess is that if the rolling resistance is all that matters, they may stay on the tracks. However, there are other factors, and the curvature and coupler lengths, not to mention car lengths, will all have a hand in the phenomenon. Even WHERE the couplers are mounted will be a factor; truck-mounted couplers are going to be more forgiving that those mounted directly to the frames of the cars.

Car length, if it is a problem, will be a problem wherever the car is placed if the couplers are not right or the curves are too tight. If the cars are too long, or their trucks are too long, or their coupler shanks too short, you won’t get two of them around tight curves let alone 25 of them! So, if the curve is the main offender, the long cars won’t work anywhere, not directly behind the loco, not just before the caboose.

There is more to this, such as trucks out of tram, wheels not spaced or positioned properly, and so on.

I had better stop and see if I am helping.

3

I think what you are refering to is more commonly called stringlining. When cars fall to the inside of a curve. I think your biggest problem is that your curves are too tight for the length of trains you are running. Usually on my layout the longest train is a 50-60, rarely 70 car through freight. Then again my mainline radius is 42". So you need to cut down train length until you get your wider curves.

In response to your last 2 questions. I dont think car length really matters in the order as long as they can make the turn. but try to put a couple of short cars between very long ones. Your cars that roll the worst should be at the front of the train and the cars that roll easiest should be at the rear of the train. For realistic operation though you should make all of your cars roll well so this doesnt affect train order. Train order is important in switching.

4

One thing that adds to the string afffect is cars that aren’t properly weighted. So you may want to look into that also.

5

There is an issue that was not outlined. The cheap life-like and Tyco are going to have truck mounted couplers while the Athearns are going to be body mounted. This will effect their performance in the curves. Truck mounted couplers follow the curvature of the track so don’t have “swing” issues. But as trains get longer (heavier) they start binding in the curve. Mixing the two in one train is a really good formula for derailments.

Rear

see above about mixing coupler mounting. For truck mounted couplers length is not an issue. For body mounted the longer the car the greater the swing and hence lateral stress in a curve. Put long cars toward the rear and don’t couple a short car to a long car.

Why?

6

Since you have a mixed-bag of car quality, check the weight of the cars. For your long-train goals, put the heavier cars in the front, and lighter ones in the back. The forces which are in play here are drag (caused by poorly-rolling cars) and weight, but weight is much more important when you’re going up a hill. If the curve is on the hill or at the top, so the caboose end of the train is being pulled up while the locomotive end is rounding the curve, you’re going to have problems. You may find that the derailment problems can be reduced by taking the curve in the other direction, if that’s an option.

7

I see that lots of excellent advice has already been offered here and I have nothing to add to it, but I’m curious:
If you have enough real estate that you can run trains that are 40-50 cars in length, why couldn’t you broaden the radius of your curves [using flextrack]? My trains are no longer than 25-30 cars, but I have a minimum radius of 30" on my main line. (I needed that so my Walthers 89-foot auto racks wouldn’t look too toylike.) In the long run I believe you’ll be much happier with wider curves in terms of appearance and performance.

8

Cudaken,

We got re-started in the hobby when my son received a cheap LL trainset for his birthday. He got another one for Christmas, and picked up two Model Power sets with military trains as well.

All of this rolling stock uses cheap trucks, with truck mounted couplers, and those are attached to the car using snap in plastic pins that are part of the truck frame.

Every one of these cars sits on the lowest priority storage shelf, and there they stay. They never get on the layout, and when they did, in the beginning, they fell off almost immediately, on curves, on turnouts, on rail joints, and on straight flat sections, it makes no difference.

Why?

Because the trucks flop side to side an eight inch of total travel, versus zero side to side play for quality screw mounted trucks. The truck mounts have up to 3/16th inch of up and down play, versus zero for screw mounted trucks. The cheap plastic pins allow up to a quarter inch of tilt, versus maybe 1/16th inch of tilt in quality screw mounted trucks.

You can bring these cars up to NMRA weight specs, you can replace the truck mounted couplers with body mounts, and still these cars are not going to stay on the track well because of the truck mounts.

When you pull these cars around a tight curve, in a long train, two things happen. One, the car slides sideways in relation to the truck, and tweo the car tilts sideways in relation to the truck. Both of these have the effect of placing the line of pull off center, both act in the same direction, and the net effect is, as you’ve noted, cars that roll over and play dead.

That leaves you two options. You can remove the trucks, fill the holes with glue and sprue or with glue and sized styrene rod, which may require drilling to size the hole, then drill and tap a screw hole, then replace the trucks, and unless you get lucky, you will need to adjust the coupler heigth as well. If you’re going to do that, you might as well repl

9

Everything above is right on and valid - good advice all around. My guess is that given the best of circumstances you will not be able to operate 50 car trains on your sharp turns and steep grades unless you do what the prototype would do. Use pushers. Take some of that power off the front and put it on the rear. Try it and see.

10

Some carefull observation and “incident” reconstruction may give you some added facts to address the stringlining. Longer cars have more overhang than the shorter cars, and thus more coupler offset, which produces forces to the inside of the curve. In addition check the offending cars to see if the corners of the cars are coming in contact further creating forces to the inside of the curve and spilling them. Car weight has already been addressed. Years ago on a layout tour I came across an individual who had used reverse super elevation to address the problem and swore by it to allow him to run 75 shorty ore cars up grades and around broad curves. I am not sure that the reverse elevation is as critical as the radius of the curves and some transitioning into the more severe of the radiuses.
Just some thoughts to help you evaluate the solutions to your issues.
Good luck.

Will

11

Your three main culprits are coupler mounting (truck mounted with body mounted, cause problems every time.) Tight curves (though I run 18" radius with 30+ car trains with no problems), and the biggie, car weight. If the cars are too light light, there’s no way they are going to stay on the track in a long train. I’ve had Life-Like standard line and Tyco trains in my youth and came to the conclusion that the cars were so light so that the cheap two axle drive could pull them easily. This link will be a big help for you. http://www.nmra.org/standards/rp-20_1.html

12

This is one of the reasons (being able to run big locos/steamers if I want to is the other) that having broad curves on my mainline is a priority–I plan on 30/32 inch curves.

Jim

13

‘STRINGLINING’?

All answers here are good! Problem is saused by a combination of things: too many cars on sharp cures, poor trucks, and ‘Talgo’ (truck mounted) couplers. Your cars find it EASIER to tip over than follow the track, So …

Answers: 1. Add weights to get 1 oz per car + 1/2 oz per inch - NMRA spec.
2. Substitute Kato trucks. Better rolling.
3. Get rid of truck mounted couplers = 100% Body mount.

Results Gauranteed! You can do this one car at a time.

OR you can run shorter trains!

14

I second the above and raise you one more thought, when you upgrade to proper car weight and go to all body mounted couplers, spend a little more and go to all metal wheelsets… They roll so much easier, thereby lowering the total drag. I have run 65 cars on 24"radius curves AND a 2% grade on a club layout. My 4 unit Stewart FT’s pulled with no problems at all. Happy railroading!

15

Why pray tell, are you using 18" curves with 36-50 car train?

Dont you have the room to broaden the curves out a bit? Say, 30-40"?

All of the previous posters have good posts which taught me a few new things and reminded me how much I hated the old tyco type cars.

16

Boy folks so many answer and lots to think about. I will answer some of the questions I was asked.

Teaxs, why 40 cars? Well I am the type that need a quest. something to look forward to. Rather it be the quality of my board, lowering my ET (old drag racer) or how many cars I can haul. Guess it a guy thing. Like my 4-6-6-4 is bigger than your E-6.[:D]

Do I really have the room to run a 40 to 60 car train. Well yes and no. For a hard core MRR do I don’t. Long main line straight is only 19’ long and unless or when I take a wall out that will be about the max. Train cover about 1/3rd of the board at 36 cars. So do I have more room for a longer train, well yes and no again.

Why do I have 18" turns. Board was made for a good sizes HO slot car track, to say the slot cars could turn on a dime comparied to the trains is a understatment. Board is only 45" wide, hences not all the turns are 22", there are a few. After the up coming bench work they will be gone.

As far as the up grading. First I am sort of done with the LL and Tyco cars as far as buying them. There are a few more of them I would like to get like the Blue Rock cars and 50 foot green Reading box cars.

I do spend about a hour a car up grading, but no where near $5.00 a car. I use Atlas axels, 12 pairs is only $3.95 a pack at LHS. That is $1.32 a car. I clean up the trucks with one of drill bite made for doing the job. Most I can get close or as good as the Athearn cars. Bachmans will get up graded Kadee couplers, get 20 pairs for $12.95. So that is $1.29 plus $1.32 plus I weigh them down with 3 pennys = $2.64 a car.

But, if I buy more rolling stock and that will be some time off now so I can afford good bench work but after that it will be Athearn.

With some luck this Thursday I will get to haul all my junk to K-10 trains and see what my PK’s E-6’s can haul. No 18’ turns on his board[:D] His reocrd is 135 cars. I will be quad headed and hope to haul 120 cars plus.

17

120+ Huh? I wonder what my ABBA Set of BLI F7’s can do.

Best of luck! Let us know what you find out.