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Discussion Starter #1
No, it has power through it (much of the time). Giving it nudge once it is stuck, there is sharp resistance, then it sort of pops on. Its like something is stuck underneath. Its definitely mechanical not electrical.

Its not the couplers. Why? Because my tester locomotive has no couplers (I accidently broke them off). Anybody know how to replace them and what to replace them with btw?

I have been endlessly fiddling with the track to get six wheel diesels to run around. I did a foam layout and much/most of it is on a slope. I now know how critical it is to not change the slope too quickly. Lessons learned. Plus the importance of the NMRA gauge.

It is a broadway limited F7A. I have had fewer problems with the Katos, but given past history with broken couplers, I am reluctant to use them as my test vehicle. The track is now all Kato unitrack. The turnouts are #4's and double crossovers. The double crossover also gives me trouble intermittently with electrical when the locomotive is halfway through.

I've looked under the locomotive, I can't see anything below the trucks that might be blocking it.

Ideas?
 

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This just sounds like something power-related.

Kato turnout are power-routing, so when a locomotive gets stuck as you describe, check to make sure you have power on both sides of the turnout. If it gets stuck in the middle of a turnout because of no power, it can get kind of hung on the turnout and will feel like it's dragging..

Those Kato cross-overs are really reliable, but I have hit situations in which I had to put another power feed to make sure there was power on both sides of the cross-over. Without it, the locomotive only made it through the first half of the turnout.

I use Kato #6 turnouts, which are pretty much problem free, and they handle Kato F units and E units just fine, except for when I don't pay attention to the way they route the power.

I'm just throwing some things out I have run into. But I'm new at this, so hopefully the big kids will wander by and can help you more.
 

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Does the locomotive rock at all when it rides over the frog? Do all wheels on both trucks on this locomotive have electrical pickups?
 

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So there was a lot to unpack in that post. Much more than a simple question about a loco getting stuck on a turnout.

Anyway, if you're sure you feel something binding, there are two things I would check. Take your NMRA gauge and make sure all wheels are in gauge, and all the parts of the turnouts meet spec. If it does, make sure that the point rails nest into the stock rails properly. If they stick out a little, the flanges of your locos can catch on them, causing the situation you describe.
 

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Discussion Starter #5
Thanks for all the advice.

I think the problem is that the front of the truck derails just BEFORE the turnout. Now why.....

Once it gets into the crossover, well its already screwed. I have taken many iphone videos (got to figure out which corner has the lens and put it down, put light behind and record and record). It always derails on a small curve section about 7-10mm before the crossover. Always derails to the outside of the curve.

Everything meets the NMRA gauges. I've gone to great lengths to make sure its all on one plane. Fiddling is my future. Just got a fancy micrometer. Going to play with that.
 

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Thanks for all the advice.

I think the problem is that the front of the truck derails just BEFORE the turnout. Now why.....

Once it gets into the crossover, well its already screwed. I have taken many iphone videos (got to figure out which corner has the lens and put it down, put light behind and record and record). It always derails on a small curve section about 7-10mm before the crossover. Always derails to the outside of the curve.

Everything meets the NMRA gauges. I've gone to great lengths to make sure its all on one plane. Fiddling is my future. Just got a fancy micrometer. Going to play with that.
When you have a loco that is derailing you need to get down close to the place where
the derailing happens. Have a good strong light. Run the loco as slow as it will go. Watch
carefully. When you see a wheel START TO LIFT...STOP! The fault is right there.

But there are other possibilities...truck swivel is not free...wheel flanges
are too deep for the flangeway...a pickup wire is hindering truck swivel...
wheels (or track) out of gauge.

However, there are always those odd balls. I had a pair of F7s. One had to
always be rear facing when consisted. If used as the lead loco it often derailed where no
other loco did but as the rear loco it ran perfectly. I swear, these things have
personalities.

Don
 

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So there was a lot to unpack in that post. Much more than a simple question about a loco getting stuck on a turnout.

Anyway, if you're sure you feel something binding, there are two things I would check. Take your NMRA gauge and make sure all wheels are in gauge, and all the parts of the turnouts meet spec. If it does, make sure that the point rails nest into the stock rails properly. If they stick out a little, the flanges of your locos can catch on them, causing the situation you describe.
DavidJones & CTValley;

The Kato Unitrack #4 turnout has some history directly related to CTValley's suggestion regarding the point rails being able to recess into the stock rail. There is a video online by Mike Fifer, of Fifer Hobby Supply, concerning a modification to a Kato #4 turnout. He marks the outer stock rail at the place where the point rail rests against it. He then pulls the stock rail out enough to cut a notch in the stock rail for the point rail to recess into. Apparently at least some Kato #4 turnouts, or possibly all of them, come from the factory with no notch in the stock rails.
I would cut the notch in the inner stock rail too, just to be thorough, and prevent any possible problem. Fifer notches only the outer rail, and also says that the Kato #6 turnout does not have the same problem. I don't use Kato turnouts, (I make my own), but I thought I'd pass this on, since David says he has Kato #4s, and CTValley's comment about points not recessing into stock rails is true for any turnout. Itt would certainly be worth checking, both visually, and with the "points" tabs on your NMRA gauge.

Traction Fan
 

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Sooooo- I finally got it fixed this morning. Partly by accident. I had identified where the locomotive had come off the tracks each time. Always in the same place. A slight curve. I checked the gauge (Got a new micrometer- anybody want to know the thickness of their garbage bags?). They were pretty much perfect. I reasoned that they would need a slightly wider gauge on a curve. I fiddled. I ended up using a dremel cutting disc which came loose while I was using it. Damaged the profile of the rail. So I cut it out, replaced it with another piece of curved rail (just the damaged part- which went onto the crossover, so I cut the rail on the crossover. Here is a picture of what I did. I know it looks messy. I'll fix it. Now, it works. All the time!

Interestingly all the wheels on my Broadway locomotives are too close together for the NMRA standards. The kato ones are as well, but are closer (but still outside the allowable deviation). Can you adjust the locomotive drive wheels on a truck to make them further apart and into gauge?
 

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That first one wasn't a curve, it was a kink! In the new version, it's better, but there is still a kink in your track work there. I'm surprised you could get anything through that original alignment. You still might want to pull that out and replace it so that you have a nice, smooth curve through that spot.
 

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Sooooo- I finally got it fixed this morning. Partly by accident. I had identified where the locomotive had come off the tracks each time. Always in the same place. A slight curve. I checked the gauge (Got a new micrometer- anybody want to know the thickness of their garbage bags?). They were pretty much perfect. I reasoned that they would need a slightly wider gauge on a curve. I fiddled. I ended up using a dremel cutting disc which came loose while I was using it. Damaged the profile of the rail. So I cut it out, replaced it with another piece of curved rail (just the damaged part- which went onto the crossover, so I cut the rail on the crossover. Here is a picture of what I did. I know it looks messy. I'll fix it. Now, it works. All the time!

Interestingly all the wheels on my Broadway locomotives are too close together for the NMRA standards. The kato ones are as well, but are closer (but still outside the allowable deviation). Can you adjust the locomotive drive wheels on a truck to make them further apart and into gauge?
DavidJones;

I'm glad to hear that you got things working!
What brand of turnout is that in your first photo? I don't recognise it.
To answer your question, yes, in most cases it's possible to adjust the wheel spacing on locomotives. Car wheels are easier, you just hold the wheelset in your hands, pull, or push the two wheels while twisting them in opposite directions. You can't do that with most locomotive wheels. Instead, I use a small screwdriver to pry the wheel out a bit. Do your prying close to the axle and in very small increments. Also pry from several different points around the wheel so that all the position change isn't on one side of the wheel.
Before prying steam locomotive driving wheels, use a scribe mark, to show exactly where the wheel is on the axle. You pry in very small increments, partially because You really, really, do not want to pull the wheel all the way off the axle. This can mess up the "quartering adjustment, which can cause serious binding problems. If you accidentally do pull the wheel off the axle, then that scribe mark will help you get it back on in exactly the same quartering position as it came off.
Many steam locomotives have groves in their axles and wheels. The purpose of these groves is to prevent the wheel from rotating with respect to the axle. This is done to keep the driver wheels "in quarter." If you look carefully at the drivers on a steamer, you will see that the drive rods are 90 degrees either ahead of, or behind, the rods on the other side of the locomotive. On a real steam locomotive this" quarter" (of a 360 degree circle) difference from one side to the other was important to the operation of the loco. On a model, it's to keep the rods from binding the wheels. As far as pulling the drivers out a little to gauge them, these groves just make it harder to move the wheel out, but it can be done.
Seeing your photos, I have to agree with the others that your track pieces are not joined as straight, and as closely, as they should be. The joints are kinked and there are gaps between the rail ends. Still, I don't argue with success, so if your track works well, and the wheels all stay on the rails consistently, that's all that really matters. Congratulations on fixing your problem!

Traction Fan 😊
 
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