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Discussion Starter · #1 ·
Hello,
I am very much an amateur with model trains. I bought the HO scale Bachmann Thomas Kinkade Christmas Express set that comes with the track and power supply. I can barely get it to make one revolution without it derailing and it's always the locomotive that derails. I'm thinking it might be the track because when I make a minor adjustment, it helps but then just derails in another section. This is the E-Z track style. I know making sure the track in connected properly is important, but something doesn't seem right here. Any ideas?
 

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As Michael suggests, model train tracks need a
solid stable base. Anything like carpeting can
permit the track to change levels which can
allow train wheel flanges to over ride the rails
and derail.

There is a test that can help you determine why
a loco derails. Go to a place where the loco
derails. Get down close with a good light. Run
the loco as slowly as it will to to the suspect spot.
When any wheel STARTS to LIFT...STOP. There
is something there that is not right.

Don
 

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Check the rail joiners (the thin metal slots where the rail sections meet). If the set came with EZ-track, you may have the plastic roadbed clipped but rails might not be level, so you will need to pull the track apart and reconnect. I find it better to align the rails first before trying to mate the roadbed.
 

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A model train, like a prototype train, can run along undulating tangent tracks without too much of a problem, and even over substantial gaps in the rail, as the US Army showed on a documentary still available on YouTube. But, curves present a different circumstance, and undulating tracks, or tracks where the outer rail on a curve is too low, will cause derailments.

But, there's more. The pilot wheels, the swinging pair just behind the 'cow catcher' (properly called the pilot), might not be swinging well and it can lift the front axles a bit if the truck is screwed in a little too tightly. Also, one or more of the 'driver' axles, the ones connected with the side-rods, might not be seated properly in their boxes. Place the locomotive on a shiny glass surface, or a clean and flat countertop, and shine a light toward you at track level, but with the light behind the locomotive. If you see light under any of the flanges, that's where the problem lies.

The connector to the tender might be stiff, and if this is the case, when the locomotive attempts to negotiate the curve that it is entering, the tender and the other cars' resistance to rolling might lift the locomotive's lead driver axle out of the gauge.

Finally, to end the most likely problems, the tire gauge of the drivers might be too wide or too narrow. The flanges must all be the same distance apart. One other thought...our models negotiate impossibly tight curves for the prototype locomotive, and this is necessary because of the space constraints the owner has. All of the drivers may, but the central drivers certainly will, have a lot of engineered 'side-play' so that the axle and connected pins and rods can move one side or the other by as much as 1/8". Maybe your axle is being prevented from this accommodation by something.
 

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My first guess would be that you've got rails sitting on top of joiners instead of through them. If you run your fingers over the rails and there are sharp bumps that is probably the case.
The next most likely would be that your engine trucks are fouled somehow.
Pick the engine up and rotate the trucks by hand, see if there's any resistance.
 

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Note that a weight-bearing truck behaves substantially differently from one that's flopping around as you lift the engine off the tracks. The idea is to lift the train, set it upon a clean, flat, surface, and use a finger tip to gently nudge the truck left and right for an arc total of about 70 deg. If there's no resistance, then that's not your problem.
Don't forget wheel gauge. There is also the problem of axles not being aligned sufficiently due to wheel placement on them. I'm talking about line-astern. Following flanges should be aligned. If a pair of wheels is in gauge, but not centered on the axle, you can get derailments at turnout frogs.

<=)(========)(=>
<==)(========)(>
 

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First if all, despite Bradford Exchange assurances, you do NOT have a top of the line piece of equipment there.

My research is showing that this is an On3 scale set -- that is, an O Scale (1/48) model that runs on HO gauge (1/87) track. That's already going to make it slightly unstable, especially on curves. ANY issues you have in your track are going to be amplified by this arrangement. When using track with attached plastic roadbed, it's easy to be lulled into thinking that it's impossible to have bad trackwork, but that's not true.

Check the following (most of these have been stated already):
1) No track segments have mis-aligned joiners.
2) Each segment aligns properly with the ones on either side -- that is, smooth curve arcs and perfectly straight legs. Even a small kink is unacceptable (this is suggested by the fact that you can "move" the derailment point around the layout).
3) No bumps or dips.
4) Track is level side to side, or at worst, VERY slightly inclined towards the center of the oval..
5) Track does not move up or down as the heavy locomotive passes over it.
6) The leading 2 wheel truck on the locomotive is free to pivot and sits firmly on the track.
7) the 6 driving wheels jn the locomotive have a little (about 1/16") side to side play, and can be perfectly aligned one behind the other on each side.
8) The tender sits level behind the locomotive, without any upwards or downwards force on the drawbar connecting the two (press down gently on both sides and see if either piece moves).

Many or most (the first 5) of those problems can be caused or exacerbated by running on carpet. If you are, Try running it on a countertop / table, or at least a piece of unwarped plywood and see if you get better results.

Good luck, and let us know what you find.
 

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Discussion Starter · #9 ·
Thank you to all who have replied. Such a massive amount of experience is evidenced in all of your responses. I took the track apart and when I put it back together, realized that some pieces fit together better than others. So through trial and error, got the track together so that all the rails are nice and smooth. The track is placed on hard, level tile at ground level. I have only the locomotive on the track when testing. It is derailing when it hits a curve and the pilot wheels are the first to derail. It will run in reverse all day without any trouble. I have tightened and loosened the pilot set many times looking for the sweet spot, but it's still derailing every time without even making a full revolution. What do you all think?
 

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It is derailing because it doesn't have enough weight on it or it can't smoothly swing in azimuth when the locomotive is seated properly on all drivers and trucks. I take it that you have accurately determined that the axles on the engine truck are in gauge.

It would be useful to place a foot-long bubble level, straight edge down on the rails, and get your eyes down as close to rail height as possible. Does the nether flat surface of the bubble level show any daylight above the rails, especially along curves. There's your problem.

For weight, you can use stickum or something like it and glue two pennies atop the truck frame if they won't interfere with azimuthal swing left and right. Or maybe some lead putty, lead solder...anything to add even half an ounce to the weight of the truck.

When you have the engine inverted and are loosening or tightening the screw, have you actually removed the truck and seen a leaf spring meant to press the truck down a bit? They interfere if not properly situated or shaped.
 

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If you refer to my post #8 above, have you checked items 6 through u thoroughly? Any of those could cause the symptoms you are describing. When you say you are loosening and tightening the pilot wheels, what exactly are you doing? Just loosening or tightening the mounting screw will only make sure that it isn't overtightened. You also need to check the gauge of the wheels, and whether anything under the locomotive is interfering with them (steps and coupler boxes are common culprits). Make sure it sits firmly on the track -- reach underneath with a screwdriver and press it down. You can also check to see if there is a gap between the tread of the wheel and the track.

Also, when you say "just the locomotive", do you mean without the tender? Because the tender may be the cause.

Get your eyes right down at track level, with good light under the loco and WATCH. You will see the wheels start to lift. Stop the train immediately and check for the cause.

And lastly, are you ABSOLUTELY CERTAIN that the pilot wheels are properly railed on to begin with?
 

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Get a NMRA (National Model Railroad Association) track and wheel gauge and verify all your wheels and rails are the correct distance apart.

Take a free rolling car, I like using flat cars, and with the lightest of touch roll the car by one finger around the track. Check out any place that even the slightest of bumps or resistance to rolling.

Al for the loco pilot wheels, can they pivot enough for the curve you are entering? Can you get one section of a larger radius to test? I suggest flex track to test as you can change the radius to whatever you want.
 
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