Troubleshooting derailing rolling stock - Model Railway Engineer

Troubleshooting derailing rolling stock

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troublehshooting derailingIf you’ve got rolling stock that always derail this may be the answer.

I’ve written before on how to troubleshoot derailing trains. That post covered the most common problems and solutions but I recently noticed a particular wagon derailed frequently and none of the usual suspects solved the problem.

No matter what I tried if this unit, a GWR wagon, was being pulled it would come unstuck.

It was only after some investigation with a magnifying glass and calipers that I identified the problem and it all came down to size.

Watching the wagon move, either as part of a rake or on its own, it would just slip off the rails.  Closer examination of its movement with Jewelers Loupe showed the front wheels to be at fault.

More out of hunch that for any other reason I measured the distance between the wheels on the axel.

It’s an N gauge wagon so this distance should have been 9mm. The LCD display on my digital calipers however showed the front wheels were fractionally closer together.


Digital Calipers?
Digital calipers measure internal, external and height and depth dimensions to great precision with the distances shown on an LCD display.

They’re a great tool for all manner of small jobs that crop up when railway modelling including not just for wagon troubleshooting but model making and checking clearance around track. I use these available from Amazon.


Something I wouldn’t have detected if not for precise measurement and digital display of the calipers, but big enough to cause problems.

This wagon was picked up a boot fair a while back and was found at in a box of other rolling stock so the wheels probably slipped when rattling around in the bottom of this box and getting knocked against other items.

I swapped wheels with a spare set I had to hand and sure enough the wagons ran perfectly.

Examining the original wheels set a second time again confirmed the wheels had moved on the axle. Very gently pushing them apart with pliers returned the wheels to their correct distance apart and on being swapped back my GWR wagon ran without further problem. Hurrah!

I’ve not seen wheels move on axles before but if you have rolling stock that regularly derails it’s certainly something to check.

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