cracked axle gears in athearn genesis locomotives

[mlwlover]

i am redoing all of the wheels in my athearn genesis locomotives to be closer to scale and i noticed that most of the axles are cracked. does anyone have a way to fix them? i was thinking of some kind of a sleeve to go over them and close the crack. i tried drilling out aluminum pop rivets on my lathe and one end is centered and the other end is off center. can anyone offere any ideas fo a fix? i can put them together as is but the wheels will not run true.

[oldmuley]

Is this the same type of cracked gear problem that used to plague the older Photo 2K models?

[mlwlover]

yes it is the same problem.

[12bridge]

Which Genesis model? How old?

[nebrzephyr]

Mar 26, 2022 9:03:43 GMT -8 12bridge said:

Which Genesis model? How old?

Yes, I 'd be interested in the answer.

Never seen this problem in Genesis engines. I have some of the very first Genesis released and they run just fine.

Bob

[lvrr325]

The solution is replace the gear, if they're available. Opening up the inner diameter a bit may prevent a future reoccurrence.

[edwardsutorik]

It does appear that the solution is to replace the "gear". I did it on one loco, and it solved the problem.

Nameless OP: have you tried that?



Ed

[upcsx]

I have one SD75 I about three years old when it came out it has a cracked gear.

[mlwlover]

the nameless op is darren montour, i think the plastic they use gets brittle over time and i have probably changed wheels too many times. i just want to find a fix before i put the bottom clip back on because if you keep taking it off it will break. i think the sleeve idea would be the best, does anyone know of a ready made sleeve with an id of .109?

[edwardsutorik]

Mar 27, 2022 6:11:28 GMT -8 mlwlover said:

the nameless op is darren montour, i think the plastic they use gets brittle over time and i have probably changed wheels too many times. i just want to find a fix before i put the bottom clip back on because if you keep taking it off it will break. i think the sleeve idea would be the best, does anyone know of a ready made sleeve with an id of .109?

Hello Darren,

It's quite possible that there is an over-the-counter item that will do the job, and that some other modeler has found it. I might have missed that.



On the chance that one doesn't turn up, I searched for "7/64 bushing" and fairly quickly came up with this:

www.mscdirect.com/industrialtools/steel-7-sp-47-sp-64-inch-bushing.html


Problems likely arise with the individual cost, plus the length.

Since you have a lathe, it seems you could make your own from brass rod--drill the center at the proper diameter, and cut it to length with a parting tool.



Ed

[lvrr325]

It does depend which engine you have; some use the same old SD40-2 gear and those are $8 for six. Some use a Genesis specific gear and while Athearn does not seem to sell the gear alone you can buy six axle assemblies for $20. The SD70 appears to have still another part number which I don't see being currently sold.

If it's the 40028 gear anything but just replacing them is not a cost effective use of your time.

[mvlandsw]

Mar 27, 2022 9:34:01 GMT -8 lvrr325 said:

If it's the 40028 gear anything but just replacing them is not a cost effective use of your time.

Unless the problem will just recur later. The whole idea of pressure fitting axles into plastic gears needs to be rethought.

A factory installed metal sleeve may be the answer.

[lvrr325]

The purpose of the plastic piece is so the wheels remain insulated from each other. I suppose you could sleeve each side, but what will that cost vs. $1.25 per gear retail?

It is much less common for the actual Athearn part to break, also. Either the Proto gear that clones it is made of a slightly different plastic, or the dimensions are slightly tighter putting more stress on it. I can count the Athearn engines I've had with bad gears on one hand. Every Proto I've had with this gear has had at least one bad one. Including units that were 15 years old sealed NOS.

[mvlandsw]

I'd rather pay a little more to avoid a predictable failure down the road. How many locos get junked by people that don't know how to make the repairs or can't deal with the process?  How many people will get frustrated enough after paying todays prices to just abandon the hobby?

I've found that many of my Kato built models have the same problem. On them the toothed part of the gear does not crack but just the hub where the axle is inserted does. You don't hear any clicking sound but the wheels can go out of gage and don't provide any pulling power.

[markfj]

Mlwlover, I went down this road many years ago and here is what I found.

On Atlas, Athearn, Kato, and of course Proto I’ve seen the plastic drive axle gears develop cracking in the axle tube area of the part. Typically the crack(s) does not get to the point that the gear itself becomes compromised and performance is affected like with the P2K gear problem. Outside of replacing the plastic gears, which is the ideal option, you can sleeve the axle tube area.

Like you mentioned, you can take something like an aluminum rivet or tube and machine it down to fit the axle. This might be the only solution if you are working on something older where replacement or substitute gears are not easy to find.

The photos below show a Walthers gray box SD45 I had which has unique axle gears that are no longer available. I sleeved the axle tubes with the machined body of a rivet and it worked, but the process was time consuming and not very practical. (Pardon the crappy photos; I took these images years ago.)





After a little research, I found a variety of round spacers available from electronic manufacturers that can be used as sleeves. A company called RAF makes hardware for electronics and their parts are available online from distributors Mouser Electronics and Digikey. 

RAF’s M0502-25 is available in either aluminum or nylon. This spacer has an ID of .106 with a -.000 +.011 tolerance which might work on Athearn gears.

M0502-25-AL data sheet

Substitute for Kato gears:

This is another “been there, done that” situation. As you mentioned, Kato gears are also prone to crack in the axle tube area. The solution here is to buy replacement wheelsets from Bowser. These will drop in with no problem and in my opinion the wheel profile looks better. 




Thanks, Mark J.
Reading, PA

[The Ferro Kid]

markfj --

This is immensely helpful! I'm sure I'm going to find cracks as I go back through my older stuff. Thanks for taking the trouble to write this up!

[mlwlover]

Thanks for the input guys, I tried the 5/32 aluminum pop rivets body and tried t drill it out with a 7/64 drill bit and the end where I started drilling is true but the other end almost goes out the side. 7/64 is the exact size of the genesis axle gears. Ithink the problem with the genesis gears are a touch too tight is why they Crack. Would the bowser/ kato gears work for the genesis gears?

[markfj]

Mar 28, 2022 19:52:06 GMT -8 mlwlover said:

Thanks for the input guys, I tried the 5/32 aluminum pop rivets body and tried t drill it out with a 7/64 drill bit and the end where I started drilling is true but the other end almost goes out the side. 7/64 is the exact size of the genesis axle gears. Ithink the problem with the genesis gears are a touch too tight is why they Crack. Would the bowser/ kato gears work for the genesis gears?

I don’t know. However I have several Athearn Genesis locomotives and will disassemble one to see if the Bowser gear will work. By the way, my Genesis locomotives are four axles, but I would assume for cost savings Athearn uses the same axle gear across all their Genesis diesels.

I’ll post photos of my finds too.

Thanks, Mark

[packer]

FWIW, the axles/gears from an atlas U30C will work in Genesis GP units. One of my GP15-1s has them. Actually wound up with better electrical contact too for some reason

[markfj]

Here is the follow up on the Genesis/Bowser wheelset swap. The short answer is the Bowser wheelsets will not drop into a Genesis truck assembly like they do with a Kato one. However, I think they can be made to work with minimal effort.

While the Athearn Genesis wheelset (shown on the left) has a larger gear, it is the same tooth count as the gear on the Bower wheelset (shown on the right).


When I installed the Bowser wheelsets, the gears mess was fine, but I heard a noticeable noise and felt some friction. At first I thought it was the gears grinding a bit. Then I realized that the truck side frames were not fully seated inward.

A quick measurement of overall length showed the difference and the reason for the noise/friction.
Genesis:

Bowser


The Bowser wheelsets are wider because the axle tips protrude out further than the axles on the Genesis wheelsets. That extra axle material was rubbing on the inside of the truck frames and preventing them from fully seating against the truck tower. 


I think the Bowser wheelsets would work if the axle tips were shortened. Of course you could always just remove the Bowser wheels from the plastic gear and install the Genesis ones. Both wheelsets have the same metal axle diameter at .060”.

Hopefully this post helped more than it confused!

Thanks, Mark

[edwardsutorik]

Good picture work, Mark!

Thanks,


Ed

[lvrr325]

Kind of interesting that Bowser produces a gear that replaces Athearn where both are a clone of Kato parts.