# Bachmann Spectrum UP DD40ax #6922



## BIgOtto (Dec 14, 2012)

I recently picked up a Bachmann Spectrum UP DD40AX #6922. It's running a little rough and it's slipping when it pulls cars. I'm running it on a couple short 22 turns but mostly 35.5's. I can run multiple other engines on the track at the same time without any power issues. Is there somethnig I'm missing here?


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## Sasha (Jul 8, 2012)

Do you mean the wheels are slipping on the track? Or is there slipping inside the drivetrain? I have four (4) Spectrum DDA40Xs, and all four had slippage on both motors where the worm gear couples to the driveshaft. It's a metal shaft that fits into a black plastic collar. That's where the slippage occurs. I simply and carefully dabbed a tiny amount of super glue, then replaced the plastic collar. Worked perfectly, and there's no slippage. These locomotives pull a lot of cars when running properly!


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## BIgOtto (Dec 14, 2012)

I've been putting together tracks since I was little but pulling apart an engine is going to be a little new to me. Your kind of speaking another language to me about collars etc. I'm sure I'll understand more once I open it up and look at the mechanics. I really like the engine. The front body is beat up a little as well but I think thats repairable. Would Bachmann be able to repair this for me or is it something I should undertake myself?


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## Sasha (Jul 8, 2012)

I don't know if my descriptive terms are what most others use, but I'm sure the experienced guys know what I'm talking about. I'm not an expert at all, but I have made lots of repairs and modifications on those particular engines. I don't know what Bachmann's policies are on repairs, though..


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## BIgOtto (Dec 14, 2012)

I've been reading alot more now and I've come across alot of similar problems with gears, drive shafts and collars.


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## BIgOtto (Dec 14, 2012)

I'm thinking the 22" turns are way to tight for it.


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## New Berlin RR (Feb 11, 2012)

the DD40AX (or DD40X as its known as also) is designed to be a "super freighter" meant to run on curves as smalll as 18" however not what I would recommend (i have one of the early Athearn units that loves to have pin issues on the truck so I think a remoter is in order for it) 22" or larger curves, more then likely its a drive shaft issue or if not its an issue potentally with where the worm gear meets the drive shaft, I haven't torn mine apart in a while and looked and compaired it to your model so I can't remember if the two were at all close tho. I may tear mine down again to look at it again once Christmas rolls around tho...


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## BIgOtto (Dec 14, 2012)

With it being about a foot long it looks very odd going around a 22" let alone an 18". That being said it seems to have trouble making 22" turns as is.


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## Sasha (Jul 8, 2012)

Having four of them all with the same issue, it's _*very probable*_ that your DDA40X (the only real designation) has the same problem. The shaft that couples the worm gear to the ball-and-cup collar (cup side) is spinning under load. A dab of super glue has never failed me.


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## mr_x_ite_ment (Jun 22, 2009)

Sasha is correct. I had a Bachmann engine that did the very same thing...it would just sit on the track and not move while the motor was spinning. I simply took the shell off and glued the two shafts together where they meet at a round collar. No more trouble!

Chad


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