Lionel Big Boy 4006 Tender Question

@FrankM posted:

I have the above, fairly certain it is a 6-28029 manufactured in 2000, purchased  it new in box a couple years ago.  Its pulling a long train of 37 Christmas cars.  The rear of the tender, where the 5 fixed axle wheels are derails when it goes around an 072 turn, actually there quarter turns, (90 degrees) with a straight section in the middle of the turns.  Seems to me that the distance of the 5 fixed axles is too long and allows the rear axle to ride up over the rail out of the turn which derails the tender.  I know 37 is a lot of cars but I have several other Lionel steam locomotives that doesn't have this problem of course they don't have as many fixed axles.  Any tricks to help this problem?

Check your track work these tenders with many fixed wheels will find and issues and derail. I had the same issue with a Lionel scale turbine, the tender would have an issue in one turn. I reset the turn and poof ran fine.

FWIW, I've pulled 70 boxcars with one of my Vision Line Big Boys with the same centipede tender, and it's never had any issue with O72 or larger curves.  However, that tender is right at it's limit on O72.  A few years ago when I first got the BB, I tried O60 curves.  The locomotive has no problem getting around the curves, but the tender derailed pretty early in the curves every time.

If your tender is derailing in true O72 curves, I agree with the comment about checking the track work.  There are certain locomotives that will seek out any defect in the track work and point it out vividly.

Thank You

Just my suggestion, sometimes all it takes is a shim one side or the other to level out the switch or even knock it up a hair to fix a problem like this.  Good luck.