My 4-4-0 recently coasted to a halt so I suspected the axle gear had cracked.  (It hadn't - that's another thread about different gears breaking.)  I ordered a new one from Parts and got this:



It's clear the NWSL gear won't fit on this axle, though it should fit on the original axle.  What isn't clear is whether they updated the material so this gear won't crack?

Looks like I may have a solution (or two.)  I'll let you know if it works.

Quotebut how did we get from a demolished worm gear to axle gears? Combination gears are often used in multi-reduction gear trains, and in the case here, are most likely injection molded making them near impossible to directly replace in any other material.

They are all part of the problematic gear train - I thought the "D" axle was an interesting aside as that is usually the gear that fails, not the worm gear.

I'm not worried about the compound or combination gear.  As you suggest, I can split them in half and pin a new worm gear to the existing spur gear.  [If you look at the exploded view of the new 2017 2-6-0, it's brass gears are pinned to keep them spinning together.]  I have a replacement worm/spur combination on its way from Dave.

Jerry, who makes gears for problem engines, is on Facebook, and has offered to machine one for me. He indicates the angled teeth will not be a problem.

I am reliably informed that the NWSL gears (I have ordered one but it is waiting for the reorganization,) do not have the "D" axle shape.  Not clear how you would fit one.

And that raises the question of these replacement axles and gears from the Parts dept.  If they made a different gear style, did they use different plastic for the gear?  Only time will tell.  I note my existing gear and axle is the same "D" style, so I suspect it was already changed from the original round axle style?  Shows no sign of wear - unlike this worm gear.

I have had an offer from Jerry to make a copy or two, so that will be the next order of business.  Should keep us all going until the Parts dept gets new stock.

I have no problem with gambles, and I may try the NWSL 24 tooth gear.  Or I'll wait for  new stock of the gears - plenty of other projects!

Incidentally, my replacement axle is a bit different. It has a flat on the axle, and thus the gear hole is a "D".  This is what I got from Parts:



The NWSL replacements are not "D" shaped, so this is a recent change.  As Mr K points out, they probably won't spin on the axle if they crack (dubious - I'd expect them to disintegrate if they crack on the squared axle!  We will see. . . )

Anyway, my 4-4-0 axle gear shows no signs of wear and it is the same "D" type, so perhaps it was already changed.

After much research and discussion, it was suggested that the gears in the 2-8-0 gearbox are probably the same, and that gear set and the individual gears are listed as parts.  "Sold Out" of course.

https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_142&products_id=9646

Quote from: Greg Elmassian on August 21, 2019, 06:20:47 PM
It would probably be best to determine what caused the problem in the first place.
And that gear that engages the worm is different from ALL the rest of your gears, notice the angled teeth to match the angle of the worm?
You need the correct replacement. Isn't it on the parts list, or have you already determined that the gearbox is only sold as a unit.

Greg

I think it's a bit late to figure out why it happened - I bought this engine recently.  My understanding from slot cars is that incorrectly lubricated nylon gears would decimate a brass gear very quickly.  In trains, I often see the reverse.

Yes, I did see the angled teeth, and No, there's no parts except the axle gear.  Bachmann wants $50+ for the replacement motor/gears, and unless someone comes up with a scrap drivetrain I think I'll end up paying it.  These locos are so nice it would be a shame to junk it.

I have a 1:20.3 spectrum 4-4-0 and it stopped moving - cracked axle gear, I thought.  (I already replaced one on my 2-6-0.)  So I ordered the axle from Parts and got on with the surgery.
Imagine my surprise when I realized it wasn't the axle - it was the first gear pair and the spur on the worm was completely worn away!



Anyone know where I can get a replacement?  The whole motor/gearbox pair is available, but for $50.40.  The gear looks just like the one on the axle, but different shaft and the extra spur attached to it.  Guess I could pin the axle gear to the smaller spur gear and use some brass tube in the hole. . .