For the price...

Repairing gears on truck axles

If you can.  Remove each wheel set and remove and clean the axle of ALL grease and residue.  I would suggest getting two medium (mill bastard) machinist files, narrow enough to fit between the gear and backside of the wheel.  push the gear as close as possible towards the lower wheel in the photo above.  Now place one file on a flat surface, place the wheel axle on top and the second file on top of the axle.  The idea is produce a knurling of the axle by rolling the axle between the two files while pressing down on the top file.  This knurl will slightly expand the axle diameter and provide tooth for the ACC (gap filling) or epoxy. to grab on the axle.

Ed

Ed

I wouldn't do that because the gear will stretch as it goes over the knurls messing up the tooth spacing where it's broken.  Super glue doesn't stick to engineering plastics anyway.  

I've read of them being made serviceable by slipping brass rings over the gear collar.  It would involve removing the wheel on one side and probably a press and lathe to make and fit a proper sized ring.  The easiest would be new gears.

Raphael, I don't think that loco is going to fit on those tracks anyway.

Paul

ACC

Thanks Prof K. and Ed.

Replacing the drive mechanism seems to be standard for these, however it's not my engine, so not my decision to make. I'll thus try the Loctite option first. I found an excellent thread about LocTite 770 in the archives here with an answer from Prof K. no less. The file idea was excellent. Gotta love this forum and the awesome participants!

Follow up questions below with my own attempts at replying to myself...

What is "ACC" which you both mentioned? Is that CA? According to this, they do mean the same thing.

I also found this thread from you, Prof K (again ), where you mention "ACC" being "Zap-a-Gap Green ACC", which on a quick Amazon search turns out to be CA.

Why use both that LocTite 770 and CA? According to the data sheet, the 770 "primer" allows the CA to stick to PTFE and other hard-to-bond plastic where the CA would not normally stick.

Thank you both, I learned a lot from your replies!

Q&A

Dear Ralf,

In order of appearance:

Understood and agreed, but if I read things right,
the P&D site shows drop-in replacement axle gears at US$3,
which would allow replacing only the broken axle gear with a known-proven alternative, 
while not constituting "replacing the entire drive mech"???

You've answered your own question, the technical terms "ACC" and "CA" are used interchangably in common conversation by many modellers to mean the same stuff as the generic term "super glue",

http://model-railroad-hobbyist.com/node/3117 

and "Zap-a-Gap" (manufactured by Pacer)
"Green" (mid-thickness gel form)

http://www.supergluecorp.com/?q=zap/zap-glues/zap-gap

is a make/model specific brandname for the same stuff referred to as "ACC" or "CA"...

Correct. LocTite 770 is designed to address exactly the kind of "CA / ACC won't stick to engineering plastics" issue we face regularly in model building. I came accross it some years ago when trying to build a Grandt Line delrin Climax Uni-sleeve-uni driveshaft into an On30 loco. The delrin assembly had to attach directly to the metal motor shaft, and Loctite 770 + Green Zap-a-Gap was the solution...
(That loco is still going strong, now over 10 years old... )

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Thanks for pointing out the drop-in replacement axle gears

I totally misread your comment -- in many O Scale forum threads which I read, people go directly for the overkill "preventive" solution of replacing the whole assembly. You are right, doesn't have to be the whole thing, I could just get the gears. I will keep this in mind. Just for the sake of learning, I am going to try the LocTite 770 + CA first. As you pointed out, it seems like the kind of thing useful to learn in his hobby.

Regards.

@ Raphael

I did a gear fix on the Athearn split gear problem using collars on the gear hubs.

Read about it here: http://www.kingstonemodelworks.com/Gearfix.html

I read on another forum where a model airplane hobbyist used a cracked gear in the drive train of and electric motor helicopter. He glued together the split gear and made a mold to pour a resin gear. He said it worked very well for him.

Bernd

Another Thought

Have you ever tried any of that "as seen on TV" super glue type stuff that is cured with the UV light?

I used some a few weeks ago to repair my granddaughter's broken glasses and it held very well.Usually I have had little success in getting glass frames repaired..

Just a thought.

Esppe over Donner

Another option is to look at

Another option is to look at Oso Railworks/Northwest Short Line. NWSL produce (or did) cut replacement gears, axles, wheel sets, conversion kits.  They produced cut metal replacement gears (that I bought) for the Bachmann (first-run) 2-truck Climax.

Ed

Cracked vs Slipping

The original post stated:

So while people are correct in how to repair cracked gears that does not seem to be the problem and so the knurling Ed suggests may indeed work just fine. Surprising there appears to be no knurling on the axle shaft from the manufacture, not sure how they initially secured the gears to the axle. Maybe the manufacture just relied on press fit and the plastic has stretched over time.

Cracked gears

On the picture the gears looked fine. Later when I was cleaning them, I re-examined them and there's a very very fine crack line along the axle axis on 3 of the 4 gears. It's really subtle and looked like merely a reflection at first. There is indeed no knurling on the axles, so creating one seem only beneficial.

Cracked

Ralf, now that you determined they are indeed cracked, then you should look at the other methods for fixing cracked gears:  https://forum.mrhmag.com/post/cracked-gears-12192527