So you've got your new layout, or maybe that new locomotive you’ve been waiting for and you're excited to try it out. Yet try as you may, the worst happens, Derailment. We've all been there, so why is it happening? And more importantly is it your fault?
Well as I said probably not. But there are some important things to remember, for one your model train is not a fairground bumper car. Now this sounds obvious, but the large trains they are based on, take long sweeping curves for a reason and your layout is likely to have sharper corners than the scale equivalent of these bends. There are limits to what a model train can do, so be realistic with your speeds when cornering, coupling or crossing difficult sections of track.
Remembering this fact will greatly reduce any derailments caused by your driving; however remember we all make mistakes occasionally.
I estimate 90% of all model railway derailments are down to one of two things, a problem with the track or a problem with the train. It’s usually easy to tell between the two, if only one locomotive or car constantly derails then the issue is most likely with that model, however if many different locomotives derail at the same spot then the issue is with your track.
For issues with a locomotive or car there are a couple of simple things to check:
A catching or stiff coupler can cause model train derailments. Also check your coupler heights and centering, if they don’t match you can often get decoupling or derailments.
Sometimes a tiny drop of light oil will cure a problem with your model train derailing. An un-lubricated wheel, or coupler, can cause a jar, which will force the wheel to catch the rail and derailment will occur.
However don't forget the effect loose oil can have on your models, including damage to paintwork and stains on your layout, so don’t use more than required.
Often you will find that modern cars are made from very light materials, whilst this does reduce costs, it can mean that there is not sufficient weight on the track to ensure smooth contact with the rails at all times. Adding a small amount of weight, low on the cars can improve running and reduce derailments. Just be careful not to add too much.
Check your wheels are not wonky and that they are all in gauge for the track you are using. Even a small difference in gauge can cause your rolling stock to catch and rub the rails or simply fall inside, both of which cause derailment.
Always remember that all of your model railway, both layout and models will require regular maintenance as wear and tear can always cause new issues. Large changes in temperature can cause expansion and contraction in the metal of rails and wheels, so you may need to adjust for season of your layout is affected.
For issues with the track often small adjustments are all that is required.
Probably the biggest cause of track related derailments, your joints should be smooth, level and well fitted. The gap between joints should be as small as possible and you can add solder to joints to help adsorb and contraction and expansion from change of temperature, filed smooth you should be able to get joints as smooth as the rest of the rails.
Again this one sounds obvious, but this can be an issue, especially on layouts that meet the general public at exhibitions. Check your rails for dirt, oil and "sticky patches" left by people handling your rails.
Like your trains, rails can go out of gauge, if you often derail in the same place you can check that there is not a wide spot or pinch in the track causing it. Small discrepancies can be fixed by heating the track with a soldering iron and moving correctly into place, or by simply replacing that section.
Points can be a big issue with derailing, moving track is the easiest to go off gauge as it has to match in two positions and often the movable switches don’t smoothly meet the rails. Usually a small file can be used to fix this but again it can be simpler for a beginner to simply replace the section.
Sadly it does happen, sometimes track can be miscast with large bumps or dips, sometimes bumps can be smoothed but it's often best to simply take it back to the shop and ask for a replacement. A big clue to this is cars becoming uncoupled at that point.
If it isn’t immediately obvious what is causing a derailment, the simplest way to diagnose the problem is to repeat it. Try the model at the same speed faster and slower, if it repeats at the same speed but not at lower ask yourself "is it me?" if you are sure it is not then work through the steps above and you will have a smooth running line in no time.
Just remember, random derailments do happen, but with a little care and attention you should be able to run your layout with the minimum of derailments.