MTH Niagara Derails

 What jumps first? The front pilot? The main drivers? It does it anywhere on your curves? 

There's only flanges on the front and rear most main drivers correct?

Are you saying you have a Lionel Niagara which negotiates the same curves without difficulty?  Are all the wheels on the MTH loco properly gauged?  (Measure the inside-to-inside spacing and compare.)

How about a video.  The MTH Niagara has no trouble on 0-72.  

If I recall correctly, the draw bar on the 20-3047 has two holes that can accommodate the tender's draw bar post.   Even on 072 track, the hole in the draw bar that is closest to the engine might not allow enough clearance between the engine and the tender.  Try using the hole that is furthest from the engine.

I would check the tender and drawbar

Is there a turnout in the turn it has to contend with?

attached is a video of my Niagara going through 0-54 curves

Thanks for all the feedback as I try to solve this issue.  I finally had some time today to analyze and answer some of your probing questions.  I measured the distance between the inside wheels, 1 2/16” same as my lionel allegheny. Flanges on front and rear trucks.  Traction tires only on the rear drivers.  Track signal is 10. I attached a video of the derailment as well as some photos of the bottom of the locomotive.   The front trucks remain on track yet the derailment happens toward the rear of the locomotive as you will see on the video.  If I run the loco with or without the tender, same result,  but drawbar is in furthest hole toward the tender. No one particular curve is a problem. 

Ok I watched your video.  Where is the tether from tender to locomotive ?  I did not see it.  Was that changed ?  The tether should be sticking up in the air between tender and locomotive. Maybe I missed something. 

Almost looks like something is physically lifting the rear of engine up.  Run it slower and keep a keen eye between the two units.

Suspect that the rear pickup roller is slightly off center. It drops off the center rail and then forces the rear drive wheels off the track.

If this is the cause, press the roller in the proper direction to center it.

Alternately, if the derailment always occurs at the same spot, place a short  section of rail next to the center rail to prevent the pickup roller from falling off the center rail.

Good luck.

Thanks.  I checked the rollers and made several adjustments with them but still did not resolve it.  Even swapped out the rollers on another engine.  Your suggestion makes a lot of sense as to why the rear would be fallong off the track  Wonder if there are wider pickup rollers but all that I have ever seen are the copper ones. I will keep trying as I am determined.

Wow. she really jumps! I have to be honest and say I haven't seen that. Usually something up front leads the engine off. Maybe even something with the spings on the pilot or trailing truck in some instances.

 The way that jumped, I like the post above about the center pick-up roller causing an issue. Is there any defect in that one spot that would catch the center roller?

I run mainly 2 rail so I don't see that happen much.

I'm still curious about the tether can you take a photo of it on straight track. Close up between units.  This happens anywhere on any curve ?   Or just this one spot ?  what happens when you turn it around and go the other direction ? What about reverse in either direction ? different speeds ?  I had two of these and never had any problem. 

From your video, it appears that the pickup roller is falling off the center rail at a kink in the curve at the joint between curve track sections.

One possible solution is to eliminate the kink.

Another solution is to install a short section of rail or a piece of 1/4” material next to the inside of the center rail where this problem occurs. ( See attached photo.) I have an MTH A-1 NYC Berkshire that jumped the track at switches. So I added short pieces of rail as shown. That solved the problem.

I had the exact same thing happen to my MTH Premeire Reading Blue Mt. T1.  Drove me nuts.  What it turned out to be was a loose screw on the tender that was hit the drawbar and causing the derailment around the curves.  Check the screws on the tender, make sure they are tight,  along with the slack on the tether.  Hope this helps, sometimes it is the less likely things that cause the problems.

I fixed the problem!  Found the rear break shoes were incorrectly installed so swapped them between the sides. Took a photo in case anyone ever has such an issue.  She performs flawlessly now and the beauty of the fleet.