Diesel Drive Axle Gears

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Joe Daddy

C & SF, my obsession
The symptom - a Diesel Locomotive hesitates, stops, then jerks ahead, momentarily shorts, or in extreme cases will not move at all.

On Athearn, Atlas, BLI perhaps all HO diesel locos I find they use a split Drive Axle with a gear in the middle to hold the two axle halves in gauge and transmit power to the rails.

To test these gears, I remove the axle/gear from the truck, grab each side and try to twist the wheels. If I feel ANY slip, it has been my practice to replace al the gears in the Locomotive.

My question, is their an allowable amount of slip?

Has anyone tried successfully to use either loctite or SuperGlue to repair slipping axles?

Thanks

Joe Baldwin
 
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trailrider

Well-Known Member
I have NOT experienced slip, but HAVE experienced cracked/broken axles. In order to replace gears on an axle assembly that is cracked, it is necessary to remove the offending plastic axle piece, usually by twisting, although a gear puller can be used. I would imagine that a ca glue would secure the new piece in place. I would use a slow-acting superglue, however, to permit checking and adjusting the gaging of the gear and wheel.
 

cajon

Active Member
Sounds to me like you've got electrical problems like opens &/or shorts by your description vs cracked gears. Check all the wiring in the loco, track & power system. You'll hear cracked gears & it will keep running.
 

jwb

Member
There are several symptoms in the OP, and some probably do come from loose axle gears. If the gear slips, the wheel goes out of gauge, and it touches metal from the other polarity, that could cause a short. The most common split axles are on pre-Walthers P2K, and I agree, the way to tell if the axle gear is split is to take the wheelset out and see if it pulls apart easily. If it does, the axle gear is cracked and must be replaced. Even if it doesn't thump or click when it turns, it's likely to go out of gauge. Every axle that slips this way must be replaced, there's no "acceptable amount".

I've had one Atlas diesel that thumps and a couple of Athearn. Athearn and P2K use the same style axle gear, pretty easily obtainable. The Atlas I need to send to them for a new wheelset or however they sell it.
 
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Joe Daddy

C & SF, my obsession
There are several symptoms in the OP, . . . . "No acceptable amount". . .
I think you are correct. BTW, the new axle designs by BLI, Atlas and Athearn are much smaller axle shaft and the gears don't split or crack (None of mine have yet) like the old larger shaft gears did, but they do slip/spin-out. Therefore the failures have no audible symptoms. Age and use seem to be the culprits. 7-8 years seems to be the magic age for me.

Athearn doesn't have the new style axle gears on their website. I have an email in to Athearn support asking the PN.
 

Joe Daddy

C & SF, my obsession
Sounds to me like you've got electrical problems like opens &/or shorts by your description vs cracked gears. Check all the wiring in the loco, track & power system. You'll hear cracked gears & it will keep running.
Thanks for your response, Andy.

It may sound like electrical problems but they are pretty easy to sort out. The wheel/gear problems are more insidious. Like I said, the new failure mode for the gears is not to crack but slip or spin-out making no noise what ever.

Joe
 

Joe Daddy

C & SF, my obsession
JWB,

Thanks for your response.
I have a set of those gears listed in my parts box, they are the old style gears. Then new style (F7) are very different looking, with a thinner gear profile and much smaller holes in the shaft. Writing this I wonder if they have a parts listing in the 'manual', wonder if i can find it.

Joe Baldwin
 

jwb

Member
I assume now you're talking about Genesis vs RTR. The ones I linked are RTR which will work with P2K. Can't speak to Genesis.
 

Joe Daddy

C & SF, my obsession
JWB,
Genesis it is, sorry for the omission. As you can see above, I did find the pn, however a quick Google was not productive.

Here is a link to the actual part number on the Athearn website, Talk about round about way to find it though.

http://www.athearn.com/Products/Default.aspx?ProdID=ATHG19254

Listed as out of stock and discontinued. . . More as I learn more

Joe Baldwin

TNT_DLGT_LAP_88.jpg
 
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logandsawman

Well-Known Member
Has anyone tried successfully to use either loctite or SuperGlue to repair slipping axles?
I tried super glue and it seemed to work for a while (a few weeks) but then gave. With replacements available, I would go that route, although loctite is an interesting idea. lasm
 

Cjcrescent

Master Mechanic
I would use epoxy instead of a super glue. And I would "clamp" the gears in a spring clothes pin to try and keep the gear teeth from spreading until the epoxy cures. Trouble with using a superglue is the superglue has no shear strength, which would be some of the force put on the gear in the truck.

There are just times you have to use the old methods to repair things like this.
 

Joe Daddy

C & SF, my obsession
Parts in stock says Athearn.

I would use epoxy instead of a super glue. And I would "clamp" the gears in a spring clothes pin to try and keep the gear teeth from spreading until the epoxy cures. Trouble with using a superglue is the superglue has no shear strength, which would be some of the force put on the gear in the truck.

There are just times you have to use the old methods to repair things like this.
Carey, thanks for your response.

The new revised and 'improved' axles and gears do not seem to crack, they 'spinout'. Also, the new setup is an outside frame so the glue has no opportunity to foul the bearing surfaces. I've had 3 locos fail with the new gears (Atlas, BLI and Ahearn) none of them have cracked so far. I would not even try to repair a cracked gear, if I couldn't get the parts new, I'd let it set in a shed somewhere. NWSL has replacement axles for the new 1.5mm axles, but I've not yet found the gears in their catalog.

I have a pair that I used super glue on this morning and will test them tomorrow.

Athearn responded telling me they do have the parts in stock.
 

dalehenigman

New Member
I've used replacement wheel/gear assys and had some where both axles touch, causing a short. axles were pretty close to gage, too. make sure your axles don't short, and if they do, file a little off the end of the axle.
 




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