You are here:

Model Railroads/engine keeps derailing


QUESTION: I have an N scale layout that I just built.  I am in the running trains phase right now checking for any kinks in my track work.  I have one (brand new Bachmann) diesel engine that will not negotiate one of my switches running forward but if I turn it around and run it backwards it works fine with no problems. What could be causing the problem.  I've checked for any obstructions in the wheels and gears and also the switch itself. All my other engines work just fine on this switch and that's why I suspect the engine is the problem.  Any advice would be greatly appreciated.  Tim

That's a real "head-scratcher".  Just out of curiosity,what brand of track are you using and just where does the loco actually derail or does it just stall.  Does it happen on one or both of the diverging sides or upon entering the other end) and how far from the turnout frog itself? The problem, if it is with the engine(locomotive) and not the switch(turnout), could have to do with the loco's electrical pick up or it might be, if only one of the trucks is powered, that the wheels on the unpowered one are not making good contact with the rail, or might be too light and not sitting correctly on the rail.  Another possibility, even if both trucks are powered is that the electrical pickup wiper on one of the trucks is not making proper contact with the rail. Also, the moving rails on turnouts can cause problems, sometimes with just one type of loco since the wheel sizes, geometry, number and type of electrical pickups etc. can vary greatly. That is called "picking the points". It that case, the moving rail is not "nesting" tightly in the groove in the stationary rail.  This can be remedied with judicious filing of the moving rail at a shallower angle.  Finally, check both ends of the loco and look for low hanging step stirrups or other pieces on the either end.  

---------- FOLLOW-UP ----------

QUESTION: I'm using Atlas 80 track and the switch/turnout is a standard right hand turnout. It derails to the right when going straight on the turnout but will negotiate the right turn with no problems.  The engine is a RS3 from Bachmann. It just derails on this turnout and none of the other 12 turnouts.  The truck in the front seems to be a little tighter then the back truck which moves freely.  I've had the engine apart and cleaned any burrs I could see on the truck and put it back together and it still derails. I have an appointment to get to but, when I get back I'm planning to switch trucks, put the front one in the back and the back one in the front and see if that will fix it. I didn't mention before that it's all, 8, wheel drive and it doesn't derail backing up in reverse over the turnout. Tim

Hi Tim,

Sorry to be so tardy with my reply to your follow up, but sometimes real life interferes with model railroading!  You seem to be very thorough in your analysis of the problem. The culprit seems to be one or both of the following two issues. The truck may not move as freely as it should or that issue in combination with a slight defect in the nesting of the moving rail or frog could be the cause.  Usually more than one issue is involved.  The only other thing you might try if the track is not permanently affixed is to exchange that turnout with another one and see if the turnout is part of the problem or not. Best of luck to you in finding a solution to your dilemma.


Model Railroads

All Answers

Answers by Expert:

Ask Experts


Larry Weinberg


I can answer many questions regarding N scale model railroading in general as well as questions about the NY Central System, especially questions about the N scale models of their passenger and freight cars.


I have been a model railroader since 1949 and have been an N scale modeler since 1971. I have an extensive N scale collection as well as an extensive model and prototype library to consult.

I am a member of about two dozen online forums covering N scale model railroading and the New York Central System. I am a member of the Northern Westchester Model Railroad Club.

College graduate/Retired.

©2017 All rights reserved.