Bachmann Mogul - dreaded split gear issue

T

Tim Brien

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About ten years ago when first released I picked up two Bachmann Spectrum Moguls on a whim. It was an expensive whim as they were $975.00 each. They really did not suit me so they sat forlornly unused in storage. Today after ten years I decided to try them out. first loco was serviced and tested. It ran just fine. Second loco got about two metres down the track and stopped with just the hum of the motor turning.

Disassembly proved to be very simple (probably easier than an Annie). I feared those dreaded eccentrics, however, disassembly does not require the links to be totally removed. I had to dismantle the loco to determine the number of teeth on the driven gear. NWSL states a 24T gear is required, however, mine has the 25T gear from the Connie (no wonder it split through). I will need to source two new gears from NWSL now that I know which part number to order (NWSL #2226-6).

Both these locomotives were purchased new from a local dealer but never tested. Today was their first ever run attempt.

I found a You-Tube tutorial on replacing the gear, however the reviewer made a statement that I have never heard before in replacing these gears. He stated that the new gear will not immediately fit the shaft and is required to be 'cut' to fit. He does not explain how he 'cut the gear'. He then retained the gear with red thread locking Loctite.

I thought that the new gear from NWSL was simply drifted onto the shaft with no bore relief required. Any thoughts from some one who has changed a gear, please?
 
Think if you got a nylon(?) replacement, then the bore is slightly too small.. - Hence the originals splitting..
Believe the early 'fix' was to bore out the new gear slightly ??

Might have this totally wrong of course!

Those I have repaired, I have obtained a replacement axle (with brass gear already on) and a idler. These as a 'kit'.
HTH.
 
PhilP said:
Think if you got a nylon(?) replacement, then the bore is slightly too small.. - Hence the originals splitting..
Believe the early 'fix' was to bore out the new gear slightly ??

Might have this totally wrong of course!

Those I have repaired, I have obtained a replacement axle (with brass gear already on) and a idler. These as a 'kit'.
HTH.
Click to expand...

phil where did you get the kit from
 
PhilP said:
Think if you got a nylon(?) replacement, then the bore is slightly too small.. - Hence the originals splitting..
Believe the early 'fix' was to bore out the new gear slightly ??

Might have this totally wrong of course!

Those I have repaired, I have obtained a replacement axle (with brass gear already on) and a idler. These as a 'kit'.
HTH.
Click to expand...


Alas, the axle replacement with the brass gear is for the 2-8-0 Connie. Bachmann still sell the original plastic gear fitted to a shaft.
 
However,

Culled form a post by Kevin Strong on the Bachmann forum..

"You can order a Delrin replacement gear from Northwest Short Line. The 4-4-0/2-6-0 gear (24-tooth) is part #2223-6, and the 2-8-0 (25-tooth) replacement gear is part #2226-6. Note, however, that despite NWSL indicating that the 4-4-0/2-6-0 gears are 24-tooth, I have yet to remove one that was 24-tooth. I've had three apart and they're all 25-tooth. Others have reported the same thing. I don' t know if there were two different gearboxes or what the deal is. If yours is slipping or broken, take it out, count the teeth, and order the appropriate one."
 
Phil,
I did just order two 25T gears from NWSL. The one removed was 25T as indicated by Kevin that it might be. For my other mogul while still working as it should be as it is brand new even if many years old), I ordered a second gear as no doubt this one will fail at some point. The cost of both gears was $47.00 including postage.
 
I've noticed that my Mogul (I call it a Centenial) is prone to locking up with its motions fouling the sliders on one side and sometimes needing a little push to start. Could this be a related problem to that of the gears ? I think I will take a look at NSWL and get a gear as a precaution. Real b@@@er if you need to reassemble the inboard "eccentrics". Max
 
It seems that a high percentage of my Bachmann locos which have not been run for while are having split gears when taken from the boxes to run again, they were perfect when put away therefore it seems that the splitting is due to the plastic shrinking.
 
funandtrains said:
It seems that a high percentage of my Bachmann locos which have not been run for while are having split gears when taken from the boxes to run again, they were perfect when put away therefore it seems that the splitting is due to the plastic shrinking.
Click to expand...

Sounds the same as the well known problems with N gauge Graham Farish locos of a certain age. I've also had a few splits in Arnold and Minitrix locos, so far they've been fixed with replacement gears sourced from small firms such as MikroAntriebe (cheaper than trying to get hold of original spares).

I know there's a view that these nylon/plastic gears wear better and are no doubt cheaper, but I long for good old brass gears! Didn't get splits with those and simple to keep lightly lubricated.
 
The NWSL replacement gear arrived and was installed. Excellent service from NWSL. Slight issue with refitting the lower cover. I had to resolder a new power pickup wire on one of the rear axle bearings. The stock wire length allows minimal access when refitting the motor.

While the gearbox was out I check tightened the motor retaining screws. As I guessed they were only finger tight. This loco was new (purchased from an authorised dealer when first released) with less than two metres running so the screws were not tightened at the factory. Similarly the rod retaining screws were only finger tight.

Locomotive has been running now for half an hour and draws almost no current (less than 0.5 amp). I will change the other loco gear (not broken as yet) in the near future.
 
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