Derailing Issue

Model Railroader General Discussion (Model Railroader)
1

Hello all!

I am here with another knowledge question. When i started the hobby earlier this year I purchased a Bachmann Industries EMD GP40 Locomotive. Att hsi point I ma basically operating on a 4 x 8 sheet of plywood and thought I would be ahead to have mainly small length cars. BUT now every time I try to run the engine around with the smaller cars they want to derail. I have checked the track height and it seems to not be the issue. Is there a rule of thumb about the length/weight of cars with an engine such as the one I mention?

2

Hi Joe. Derailment issues can be frustrating and take effort to troubleshoot. It might be the cars, it might be the wheels, it might be the track, and it might be the couplers.

The cars. Yes there are standards for car weight that the NMRA has propounded and you can find them (and other helpful discussion ) here. http://www.nmra.org/beginner/weight Some guys say the NMRA standards are excessive. What is really important is that there be enough weight, correctly centered in the car, and that it be reasonably consistent with the length of the cars. To mix overweight and underweight cars particularly on tight curves can indeed result in derailments. Is it possible to put some sorts of weight on all your car’s roofs or tops - and if so, do you still have the derailments? If they cease then weighting of cars is a likely cause of the problem or at least one of the causes.

Wheels and flanges. If the wheels are not to correct gauge (which can and does happen) that can cause derailments on curves and in particular where straight track meets a curve. Also on switches. If flanges are too deep they can derail on the frogs and guardrails of switches. The NMRA makes a handy took that measures gauge and flange depth and much else besides. Many hobby shops sell it.

Track. Track can also be out of gauge although thankfully that is now pretty rare. The NMRA took also tests for that. But there might also be kinks in how you laid the track, or even sometimes the rail is resting ABOVE the railjoiner rather than in it. Notice any rough spots when you run your finger on the top of the rail? Are there visible gaps between rails on one side that are not matched by the same size gap on the other side? That is a likely kink assuming you have sectional track.

Also, there might be irregularities in how the tr

3

Joe,

I am assuming HO scale here?

If so, NMRA recommendation is : 1 ounce, plus 1/2 ounce per inch of car length.

So, if the car is 6 inches long, it should weigh 4 ounces, 8 inches long would be 5 ounces, etc…

However, I would ask a few questions in addition.

What radii curves? What type of track, as in flex, Bachmann EZ-track? Kato?

Are there any joints that are “off”: Not seated fully, kinked, where one rail sits above another?

Flat or grades?

What style couplers? Truck mount, or body mount?

Is it always the same spot? Same car?

Metal wheelsets, or plastic?

What type of cars? Freight, passenger? If freight, box car, flat car, well car, hopper? Mix?

And, define small length cars, 40’, 50’, shorter, longer?

EDIT: Look like some of this post got Ninja’d in above me…

4

I am assuming you are in HO. I am also assuming that these problems have been there pretty much from the start.

Do your cars have body mount or truck mounted couplers? Sometimes running a mix of the two can cause problems. If you started with cars from a set that had truck mounted couplers and added some with body mounts, that could be the issue.

Also, get an NMRA gauge to check wheel spacing. If you have a car that the wheels are too wide or narrow, that could cause problems. The gauge can also be used to check coupler height an track width, as yo may have a piece of track on one of your curves that is out of gauge.

Yes, there are weight standards. There is a formula, which I can’t remember, but a local club printed up a nice little card for visitors to their show. 40’ cars 3.75 oz, 50’ cars 4.5 oz. These are NMRA standards and a full list can be found on their web site.

Good luck,

Richard

5

Can someone clarify the difference in body mount and track mount couplers?

The more i think about it I wonder about the engine coupler. Sorry for the lack of details.

It is HO Scale. My track is Atlas Code 100 laid on a piece of plywood at this point as I think about my layout design. The rolling stock i am using is the smaller box car types.

6

A truck mounted coupler (sometimes called a talgo truck) means the trucks have an attachment to the coupler, so when the truck swings on a curve the coupler swings too. While in theory that can work better on very super-sharp curves, truck mounted couplers tend to work poorly when backing up because of the sideways lateral forces they exert on the wheels. Also on locomotives, truck mounted couplers typically mean that a gap has to be left in the ends for the coupler to swing, meaning the locomotive does not look very realistic.

Body mounted couplers are attached to the body of the freight car (or locomotive) as do the real prototype couplers. They work better on regular curves and when backing up, and look better because the cars and locomotives do not have to be modified to accept them. On sharp curves, however, body mounted couplers might swing out towards the rails rather than be centered, unless the coupler draft gear boxes allow for plenty of side play.

I do not know your Bachmann engine but some of the older Bachmann engines had truck mounted couplers. It might be that when the coupler moves because the truck under the locomotive has enterred a curve, that the coupler is grabbing the car it is coupled to and trying to make it move too. Is that where your derailments occur – the first car after the locomotive? Again it could be a kink in the track at crucial points. Or it could be a bit of a bump where your track is held onto the plywood (even cork roadbed can have bumps which is why guys sand it down a little before laying track on it).

I suspect I (and the other guys who have posted) could be more useful if we were just THERE to see your layout and trains. Do you have any model train friends who have a bit more experience who could visit and take a look?

Dave Nelson

7

Unfortunately Dave I am a man on an island right now. I don’t know any friends in the hobby. I have found some great sources of wisdom at some local train shops and plan to visit my first show in a couple of weeks. I am trying to read all i can and ask questiohns, but the learning curve is steep.

8

Hi Joe:

Try not to worry about the learning curve too much. Eventually you will get there, although problems like the one you are experiencing can be very frustrating.

You have received good advice so far but I would add one point. Make sure your wheels spin freely. You should be able to give them a flick with your finger and they should spin for a couple of seconds. If some of the wheels are sticking that can cause ‘string lining’ where the cars are being pulled to the inside of the curve.

I put all my cars through the same test/adjustment procedure:

  • Install metal wheel sets if the cars don’t already have them and then make sure they spin freely. I buy InterMountain 33" in packages of 100. Good quality and good price. I check the wheel spacing with an NMRA gauge but I have yet to find an InterMountain set which was spaced wrong. If you are doing passenger cars, use 36" wheels.

http://www.modeltrainstuff.com/Intermountain-HO-40055-33-Wheels-bulk-100-p/imr-40055.htm

  • Install Kadee #148 couplers and check their height and trip pin clearance with a Kadee coupler guage. Most of the time I find I need to raise the coupler height a bit. Kadee sells fibre washers in two thicknesses that go between the the truck pivot and the bottom of the car. There are other solutions if the washers won’t do the trick.

http://www.kadee.com/htmbord/page14.htm

http://www.kadee.com/htmbord/page208.htm

http://www.kadee.com/htmbord/page209.htm

http://www.kadee.com/htmbord/page206.htm

  • Bring the cars up to recommended weight using the formulas mentioned in previous posts. I use lead sheet but you can
9

First and foremost don’t get hung up on the learning curve our models can be forgiving if we help them.

First,let’s not worry and get tangled up the weight of the cars.There are other factors at work here. I never found the need to follow RP20.1 since 100% derailment free operation is found in proper track laying and all wheels in guage and couplers and trip pins at their correct height. This comes with early experience in the hobby since nobody likes derailments…

1.If you haven’t done so then buy a NMRA gauge-very important to check wheel and yes track guage.

  1. If your cars have truck mounted couplers then those cars can be easily converted to body mounted couplers.

3.The KD couplers and coupler height gauge can work wonders and save a lot of derailments.

4.Track. Even sectional track can be laid for derailment free operation I’ve used it on small 1’x6’ switching layouts with zero issues.It just takes extra care when laying it. Switches should be checked with a NMRA guage before and after installing the switch… Any bad switches should be returned or fixed once you gain experience.

10

[I assume in what follows that the various axles on the rails are all in gauge.]

A string of cars has to be substantial in order to derail a locomotive. If your string is as few as 10, it’s highly unlikely that the trailing resistance, and any other problems back there that may be extant, are causing the locomotive to derail. Instead, look for either track problems or problems with the ability of the trucks to pivot sufficiently on curves without contacting some part of the frame or details.

In my experience, derailments, if the gauge is good throughout, and if the flangeways check out, especially through the points and frogs (including through the guards), the rails are dipping someplace or rising someplace, and not evenly across them. One rail, usually the outer on a curve, is too low; the flange on the outer wheel, often on a leading truck, will pop across the rail head. When that happens, the flange on the opposite side of the axle has nothing against which to resist, so that wheel follows and it falls onto the ties.

One other possibility that is most common is a curve that got away on you. It is actually somewhat tighter in radius than you had thought.

Finally, instead of flowing smoothly at a joint, the rails’ ends actually form a kink. On tight radii, especially at the minimums engineered into the rolling stock, even a very slight kink can make the difference.

11

Joe,

A suggestion on finding someone to come take a look at your problem. You say that you have a local hobby shop. Make up some little cards with your name and phone number (best not to leave address for now) and ask the folks at the counter to give them to local modelers that shop there. By doing it that way, the owners are not breaking confidentality of their customers, by giving you their name, but you have offered yours. Hopefully someone will respond. Also, at the show talk to the members of the group putting it on and other groups from the area that are at the show, you could visit the club and maybe find someone to look things over for you. Whether you join the club or not is up to you, but most clubs are looking for more members, thus put a good foot forward.

I have been surprised to find out the number of people living nearby, that I have known for some time, and didn’t know they had layouts or at least an interest in model railroading.

Good luck,

Richard

12

Island or not, if you have a smart phone, you have a lawyer, and you have Youtube. Take a close up video of your derailment, with decent lighting and avoid panning the phone too much or we will get sea sick. At least I will.

I transfer the videos to my laptop, but maybe you can upload them directly, and I think you need a gmail account to upload videos, but that costs nothing.

Make sure your upload video is not upside down or sideways then post the share link here.

13

I would check to make sure that there’s no gunk or fibers or other stuff stuck in the cars anywhere, and that the screws on the trucks and coupler boxes are not too tight. And make sure that your track is level and not flexing too much.

Short cars and a 4-axle diesel should not be having trouble going around an expanded trainset oval, whether the wheels are plastic or metal and whether the couplers are horn-hook or operating knuckle.

14

The otter consideration that the LION has observed, but yet has not been mentioned here yet is where thid the truck derail? IT MIGHT NOT be the spame place where the train derails.

A wheel might be riding off of the rail for some distance before the train derails. LION has a problem with some trains (not all) getting thier derailment started just north of Union Square, but it threain does not derail until is arrives at 34th street. Somewhere in the tunnel the car, not riding on the rail correctly strikes the tunnel structure causing the major derailment.

Put plenty of light on the subject, and while watching carefully , observe the wheels as they approach the problem point. If one is off of the track when it arrives here, the problem is elsewither, ergo, over there, usually in a tunnel where you cannot reach or observe it.

Or it could simply be that your tail is on the tracks. Do not let your tail get on the tracks, or even on the layout.

ROAR

15

A GP-38 counts as a “short” four axle locomotive, as opposed to say an E9. It ought to work just fine with 40 foot cars. Or any other length car. The other posters have covered all the derailment tricks that I know of, so I won’t duplicate their work.