Large Scale Central

Bachmann 4-6-0 Periodically Stops and Whines

Aloha,

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!

Eric

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.

Eric,
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.

Eric,

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.

4-6-0_Gearbox

Eric,
There is some information available here:

http://www.girr.org/girr/tips/tips1/big_hauler_tips.html#mounts

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.

Ugghhhh…

Eric

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

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…

Eric