Large Scale Central

Bachmann 4-6-0 Periodically Stops and Whines


My favorite roundhouse queen, North Star, is back in “his” favorite place again: the workbench.

This time, “he” runs fine for several minutes, gets progressively slower on the curves, and then eventually stops. Power is still flowing, as I can hear the engine whine. If I give the old boy a push, “he’ll” go for a couple yards, stop, and whine some more (petulant little thing!). The same thing happens in reverse. At first, I thought North Star ate his gears (again). Over a couple evenings, though, I placed him on the tracks, and “he” ran fine. Long runs, however, resulted in the slow-stop-whine pattern listed above. I should mention North Star got a new chassis a couple years back with nice metal side rods. I understand these don’t have the gear issues of earlier models.

I am hypothesizing that the motor is somehow rising out of its mount, causing the worm to disengage while we are running this loco, then, over time, it settles back into place. Looking at one of the spare chassis @dansgscale kindly sent last summer, though, I don’t see how this is possible. The motor bolts to the gear box pretty firmly. Does anyone have any better theories or previous experiences that could guide my troubleshooting? We can crack North Star open (again), but, to be frank, beyond shredded gear bits and loose mounting screws, I don’t know what to look for.

Thanks in Advance!


I think you are on the “right track”.

Can you run JUST the chassis so you can view what is actually happening?
That wouldn’t look great, but at least you could see if your theory is correct.
Optionally, running it on a test stand might give you the same insight.

If I remember correctly, and that is always open to question, on some of those early bighaulers there was indeed an issue with the motor tilting up out of the cradle and allowing gear slippage. The quick and dirty fix is a cable tie wrapped around the gear box frame/motor cradle and cinched down tight.


If your gear box looks like this, then a tie wrap is not the answer. It would help (as Bruce stated) to get her down to just the chassis and run it on the track to see just what is happening under running conditions.


There is some information available here:

Thanks, everyone. I’ll see if I can get North Star stripped down this weekend. I was hoping to avoid that. We have had to strip it and rebuild it so many times, the tabs on the boiler are getting brittle and at least one of the screws in the bottom no longer bites.



This might call for a small sliver or two of plastic glued in the hole to give the screw a fresh bite

Or, just the next larger screw size…and drill and tap for it.

Thanks, everyone.

I field stripped North Star this afternoon. Nothing seemed out of wack:

The gears are all aligned with no significant wear obvious. The gear box itself and motor cannot rotate up away from the drive gear. There is some wiggling, but no more than in another 10-wheeler chassis I have from the @dansgscale supply pile. There was nothing obvious hanging into the gear box, either. I didn’t want to cut all the wires leading up to the light, smoke, on/off switch, etc., so I put the chassis on the blocks, applied power to the drivers, and let it run for 5 minutes. No issues… I saw no gear slippage; the driver didn’t wander; the worm didn’t lift. I also turned the chassis over, removed the plate, and made an inspection. No issues.

I’ll let just enjoy North Star for what “he” offers, consider retiring “him” to Christmas service, and contemplate saving for a new mainline, American profile loco to serve the rest of the year.


Eric, I’m working on a couple of 4-6-0s with cracked final drive gears. On one it is very hard to see the crack. Try holding the final drive gear so it can’t rotate, and try turning the wheels. (Don’t try too hard or you may crack the gear!)

The other possibility is the worm. (That and the final drive are the only gears in this rig that are tight on their axles.) It is very unlikely - as you know, removing worms from Bachmann motors is not easy!

@PeterT , Thanks. I had buttoned North Star up, but, no worries, my other tests were for naught, so I will be able to try this shortly!

I did want to see if I could isolate a cause by running the train (loco, combine, coach, and drovers caboose). It ran for 10 minutes, the it stopped and whined. I pushed it off to an electrically isolated passing siding and let the train sit for an hour. No joy… I let it sit for another couple hours, and I got about 5 minutes of run time. Pushing the loco got it rolling a bit, but, inevitably, it would stall. I lifted North Star’s drivers off the track so only the leading truck had power, and, sure enough, they started to spin. Clearly, this is a load-induced condition. I put North Star back on the tracks, coupled up the coach, and off “he” went, but not well.

So…bad motor? Or is it a slightly cracked gear that starts off OK then, under load, slowly loses adhesion to its axel? Either way, it’s back on the shelf for North Star until I “De-Christmas” the lanai 6 January. Our LGB mogul Neurenberg will have to head the Christmas gloss this year, it seems…


OK, it is time to turn to on the roundhouse king, North Star, our B’mann 10-wheeler. To review, we swapped the chassis out a couple years back ( see Another Weekend, Another Fried Locomotive – Bachmann 4-6-0). Last Christmas, the old boy started to stall under load and to emit a whining sound when stalled. Visual inspections noted no obvious damage to gearing. Christmas festivities, the Mik, and sundry other projects relegated poor North Star to the shelf. Until now…

Today I ran North Star with no load. “He” ran for 10 minutes, then started binding on one of our R1 curves.

If you turn up the volume , you should be able to hear the whine. I pushed North Star, “he” got underway, and shortly bound on an R1 turnout. I included a video as the whining sound is a bit clearer.

I have Dan Stuettgen’s @dansgscale spare chassis and gear boxes, so that treasure trove is an ace in the hole. I also invested in some test rollers this year, so that should make a more scientific approach to the repair possible. On the downside, this loco’s age has left its plastic brittle, so many of the mounting tabs are broken. The poor thing has served as a classroom in loco repair, and my multiple ham fisted tear-downs and amateur repairs have left holes for screws stripped. I have explained to the crew that this may be North Star’s last trip to the shops before becoming a seasonal static display.

B’mann’s color scheme had allowed North Star to be a year-round favorite. “He” got us a spot in GR pulling the afternoon passenger express. I figure the old boy deserves one more tear down to see if he can return to at least special duty service (That and this is also on my 2022 goals list ( Triple O – 2022 Plans & Objectives)!).

Off to find my screwdrivers!



Kid-zilla and I set to work after reviewing this thread and the referenced Bachmann Big Hauler Tips. The first order of business was stripping North Star down and getting the chassis on the rollers to see iwhat we could see:

Holy shake, rattle, and roll!

We compared that to Dan’s donor chassis:

We selected the one that was most similar to ours for a test run of what we called the “Ghost Train,” meaning a 10-wheeler chassis with nothing but its weight pulling a train.

This removed the likelihood that this was an issue of the track, but it brought us back to Bruce’s (@Bruce_Chandler ) suggestion of last December that we figure out a way to run North Star’s chassis and see what happens when it binds. That’s really a lot of wires to cut and solder, so Kid-zilla and I loosely placed the boiler and cab on the chassis, ran the old boy until it bound, and while he held the boilre and cab, I jammed the phone (CINCHOUSE made me get a phone this year) into the gap to record what was going on:

Yay! Now we knew what the problem was! The aforementioned “Bachmann Big Hauler Tips” website said all we have to do is a tap a hole through the gear and axle and drop a pin in it. If only I knew how to do that… I am assuming my Dremel is too weak. Would my Black & Decker drill do the trick? Better yet, could I get away with a drop of CA glue or gear glue?

Never has one locomotive with so many details had so many design faults that offer so much teaching potential for the budding garden / large scale railroad enthusiast.

Have a great week!


Hi Eric,
First - the shaking is due to you running at full throttle and the wheels not being perfectly aligned on the axles. They are almost all like that. If you slow it down you will probably be able to see which wheel isn’t rotating perfectly!
The phenomenon is essentially normal for running on blocks, as we all run them too fast. And in my experience there’s nothing you can do.

Looks to me like the final drive gear is slipping on the axle. Probably cracked, like this one (4-6-0 on the left):

Don’t even consider it. That’s a 6mm stainless axle, and without a professional drill press you won’t make any impression on it.
Glue won’t work on the nylon gear if it is split, in my experience.

The gear is available as a spare from Jiro Yeramian - he made some for me last year.

I may have left my spare in Florida (sorry) but he has more. Do you want the whole how-to remove the old and replace with the new? I’ve got photos somewhere. . .

Pete, (@PeterT ),

Thanks. I just tried to PM Jiro via FaceBook. If he has any left, we’ll go from there.


He can make more. And I have a spare.


Thanks Pete. I ordered two from him just now. We should have North Star back on the tracks in good time, though I may retire the old boy to special service duty.

I cannot express how excited I am to get to tear apart a gear box. :rage:


I can tell.

A few tips from my days taking them apart. The pins holding the rods just pop out of the wheels, and an easy way to put them back is an adjustable wrench - like this.

The gen5 units have a pressed in wheel center that hides the screw, and can be pushed out from behind:

Here’s what it looks like when out, and you can unscrew the wheel.:

Then, with the various bits only held together by wires, you rest bearing and the side of the gearbox in your vise and tap the axle through. Replace gear and repeat tapping to get axle back.


Thanks! This validates my decision to buy two gears…just in case!