I recently acquired a BLI N&W Class A DCC + sound locomotive. Only one problem - the tender derails when going around a curve in reverse, with no load/cars. The radius is 33.5".
I think the problem is with the six wires that connect the loco and tender, coupled with the tender pin connected to the second hole in the drawbar. I did that to close up the gap between the tender and loco.
I suspect either the drawbar is either interfering with the leading truck pickup, or the wires are forcing the tender off of the track.
So, I am curious if any readers have encountered the issue, and what they did to resolve it.
You may be looking in the wrong place. Despite their bult-in sound systems, BLI tenders are known to be rather light and they sometimes don't track very well.
I own two of the BLI Santa Fe 3800 Class 2-10-2s, and both tenders derailed regularly until I checked the tender trucks to see if they sat pefectly flat on the track.
They didn't.
So I dismounted the trucks and had to physically twist the front trucks of *both* tenders until all 6 wheels sat down on the rails at the same time.
The rear trucks weren't twisted like the front ones, but the front wheels of the rear trucks *were* being held about .015 above the rails by the tight -and imperfectly alligned- rear truck screw. So I drilled out the rear truck's mounting hole a few thousandths of an inch and twisted the drill bit from side to side and front to back while I was drilling it; working on the theory that tender trucks should work like car trucks: one able to pivot but *not* able to flex (which keeps the car from wobbling), and the other truck able to flex a bit in all dimensons in order to track better over uneven rails, switch frogs, etcetera.
Now the rear (but not the front) trucks are free to pivot a few degrees from side to side and front to back, and I haven't had a single tender derail since; moving either frontwards or backwards.
The other thing I noticed was that the hole in the engine's drawbar was a rather tight fit to the pin mounted on the front end of the tender, and since both are made of plastic the friction between them sometimes tends to either lift or depress the front end of the tender as the engine transists onto or off of grades or passes over uneven track.
Again, I drilled out the hole in the drawbar just a few thousandths of an inch, and it no longer hangs up on the tender pin, or trys to lift or depress the tender body.
One thing: If you decide to try this, be aware that the plastic BLI uses for their trucks is rather soft, and it's easy to take off more than you really want to.
[snip very useful advice, which applies to any rolling stock BTW]
I'll just add that the tender should be weighted to NMRA RP20 guidelines:
weight of car = 1oz + 1/2oz per actual length,
eg, if it's 4" long it should be 1oz + (4 x 0.5oz) = 3 oz.
IMO, a tender should be a little heavier, because of the way the pushing forces are transmitted from the engine when backing up, so I would add an ounce to the calculated weight. But if tracks fine at teh recommended weight, leave it as is.
Twibil wrote: : : You may be looking in the wrong place. Despite their bult-in sound : systems, BLI tenders are known to be rather light and they sometimes : don't track very well. : That is what I thought, but at 7.5 oz, it is actually over- weight, at 6" long. : : So I dismounted the trucks and had to physically twist the front : trucks of *both* tenders until all 6 wheels sat down on the rails at : the same time. : : One thing: If you decide to try this, be aware that the plastic BLI : uses for their trucks is rather soft, and it's easy to take off more : than you really want to. : Thank you - you offer a lot of good advice. I think I actually got it wrong - it appears the rear truck derails initially, then the front truck eventually derails. I'll have to investigate the mounting wheels, but I suspect even 33.5" radius curves are too sharp for the forward drawbar location - the tender behaves itself when it is on the rear mounting hole.
I am thinking the cab swing, due to the pivoting rear truck, is forcing the tender off, since that moves the connecting wires, which appear to force the tender to derail...
Frank A. Rosenbaum wrote: : Does the locomotive have a 'deck plate' that spans the gap between the loco : and tender? If it does, and you are using it, could the deck plate be : jamming and lifting the tender? : No, no deck plate, fortunately.
Bruce Burden wrote: : : I recently acquired a BLI N&W Class A DCC + sound locomotive. : Only one problem - the tender derails when going around a curve : in reverse, with no load/cars. The radius is 33.5". : RTFM, Idiot!!!
Sigh. First page, second step (or so) says to tuck the wires from the tender back into the tender. Once I did that, I had a derailment in reverse, but then it seems the loco acheived a happy medium with the tender, and no longer derails the tender in reverse.
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