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Bachmann HO Scale EMD GP40 Locomotive Derails

Trevor W asks readers:

“I’m finding my Bachmann HO Scale EMD GP40 loco derails at different spots along the track and it’s not happening with my other engine. I sense it could be a power or wiring issue as it is a bit sluggish at times. I recently did redo a large portion of my track and the problem has started since doing that, so wonder if that has contributed. What would be my best course of action for resolving this problem please.”

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14 Responses to Bachmann HO Scale EMD GP40 Locomotive Derails

  • Check the drive shafts inside the engine. May not be “locked in”. Then check your traction belt on the drive wheels. May need replacing

  • Richard Bakersays:

    Hi Terry,

    Are you running it on the correct track?

    Does your class 40 have 12 wheels? My Bachmann Class 37 doesn’t run that well on R605 rail so I run it on R607.

  • Russ Graysays:

    if you are using the snap together track make sure you have snapped it in the proper alignment, run your fingers over the joints to determine if they are uneven. I had that problem and the track appeared to be even but looked very closely and found out some were uneven. Fixed that problem and I had no more derailing.

  • Robertsays:

    You don’t say whether the derailing occurs on straight or curve. If you have redone the track then you should lay a ruler along each rail to see if there are hills or dips that would contribute to the derailing also check the track gauge as if this has spread then wheels will drop. If you have redone a curve check that the radius isn’t too tight for the loco bogies.

  • Anandasays:

    Check the wheels and the track with a gauge to make sure they are properly spaced.

  • JR Edwardssays:

    Three things to check, on the loco itself:

    Internal drive shafts for free movement and security,

    Free movement in both directions of the pivot points.

    Back to back dimensions of the wheelsets with the correct gauge.

    The design of the bogies with some types tends to have the centre axle installed at slightly higher ride heights to allow for lifts in the track, it reduces the tendency for the lead axle to derail at pointwork and curves, it is hardly noticeable, turn the loco upside down and lay a fine steel rule across the axles inside the wheels, the centre one should move up and down very slightly to allow for hogging, if it does not or any axles appear to be raised over height it needs looking at and could be the cause of the derails.

    The layout,

    Check the type/make of track, some rolling stock is noted to have problems with some older types, some older track makes have issues with newer rolling stock.

    Look at were is derails, mark it, try it a number of times if it occurs at these points the issue needs sorting out, relay or adjust, tight radius curves can cause issues.

    Pointwork, frogs & check rails, insular frogs, the plastic can at times be of dubious dimensions and need a little fettling, check rails can also be a little tight, a few wipes with a file can sort this, Hand builts, well someone did something wrong,

    Without finer details of were and when it is derailing not much else we can advise.

    • Michel VALLIERESsays:

      check if engine have tyre to big its aproblem i have resolv with bulllfrog snot

  • Norm Eddysays:

    Use a Kaydee rail gauge all over the layout , make sure all is secure and check periodically . Dampness can do a job on a layout. If needed use a dehumidifier

  • philsays:

    you say the other engines have no issues, so that almost takes care of the track. Check wheel gauge with NMRA gauge. Ensure the trucks swivel easily and move fore and aft along with laterally. My old Spectrums I had to loosen the truck screws a little. Watch as the engine hit the problem areas to see what may be an unknown cause.

  • Ralph Cunninghamsays:

    From what you say I’d guess it’s your trackwork. Trackwork is CRITICAL (I don’t recommend sectional track, too many joints) and must be done with the utmost care. Check the gauge and fix any dips or high spots. Also make sure all joints are smooth both on the top of the rail and on the inside where the wheel flanges run. I always made a transition into any curve, especially if you are using tight radius curves. Next check the gauge of the loco wheel sets and be sure they swivel freely. Hope the other comments and mine help you to solve your problem.

  • Dale Tronfalesays:

    If you’ve spiked or nailed the track down you could have driven the spikes/nails in too far and pulled the rails inward thereby changing the gauge of the track. If that is the case, the engine wheels, being more rigid in their frame, will lift up off the track and derail. Pull the nails/spikes back out and spread the rails back out to their normal gauge width or replace that section of track wherever the problem occurs.
    As others have pointed out, check the gauge of your wheel sets on the engines as well as your rolling stock and make sure each wheel/axle is the same gauge. Under or over gauge wheels will derail just for that reason. Also, as others have stated, run your fingernail along the inside edge of the rails and identify and fix any snags you find. Those will derail some cars and engines as well. Also ensure that the transition from a curve to a tangent piece of track is smooth and flawless. Sudden changes in the rail could make a car or engine jump and derail. Just my two cents worth.

  • Timothy Morloksays:

    When you check your wheel sets with the gauge also check the flange depth. Some older equipment does not run well on the newer low profile rail, ie: code 83 verses older code 100, because the deeper flange depth causes the wheels to bounce off each tie/sleeper plate and turnout frog rather than riding smoothly on the ball of the rail.

  • Bill Poehlmansays:

    I agree with Timothy Morlok…Older equipment may give you problems with Code 83 track. Also, if you use the snap track or EZ track systems, you have to be aware of the fact that the track will creep apart with use and needs to be correctly installed and constantly inspected. Also, the track and wheels need to be cleaned regularly. To keep the track in place I use a dab of clear silicon seal caulk. I have only room enough for a 4’X8′ train board and I change the entire layout about once a year and find that the caulk is easy to remove and does not damage the track sections.. About 60 years ago I tried to nail each section of Atlas track with the small track nails and the following year when I tried to change the layout, I ruined half of the track sections. I’ve been using silicone seal since it came on the market.


  • Kevin Chingsays:

    You don’t say if you have ballasted the track or not this could be a problem with older loco’s with deeper wheel flanges or some ballast has lifted the track or it’s too high against the rail everything else seems to be covered. Also, check if it’s derailing at a join in the track it may not be aligned properly or the fish plate may have moved and the join is spreading when the loco goes over it. enjoy the hobby these things are a nightmare some times.

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