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Effective Repair Of Cracked P2K Gears Locos and rolling stock
Reply
Frequent poster 539 posts Rasselmag Frequent poster 539 posts
Rasselmag

Hello,


[dsc029915ujzd]
The usual case with this elder P2K locos, the axle gears are cracked causing some failures like out of mesh gears (clicking noise), out of gauge wheelsets because a lose seat of teh half axles and at least lost of tractive force.

Remove the wheelsets:

- put the loco upside down in a cradle; removal of the shell is not necesssary

- pry the gear covers with the aid of a screwdriver off

- lift wheelsets out

 

 

 

[attach:fileid=/sites/model-railroad-hobbyist.com/files/users/Rasselmag/DSC02992.JPG]
[dsc02992jzjyv]

- obtain replacement gears,

either from Athearn: http://www.athearn.com/Products/Default.aspx?ProdID=ATH60024

or from A-Line: https://ppw-aline.com/collections/miscellaneous-re-powering-parts/products/40005-replacement-axle-gears-set-of-6

or from Walthers: 920-584408 

But Walthers now offers only complete wheelsets: https://www.walthers.com/catalogsearch/result/?q=920-584408+gear

 

 

 

[attach:fileid=/sites/model-railroad-hobbyist.com/files/users/Rasselmag/DSC02993.JPG]
[dsc02993mzkr1]

- pull the half axles off, it's easy going

- throw the cracked gears immediately into the thrash bin (for that they don't fool you anymore)

 

 

 

[attach:fileid=/sites/model-railroad-hobbyist.com/files/users/Rasselmag/DSC02994.JPG]
[dsc029940uj3a]

- refit the replacement gears, this is a thougher job because the new gears have the right press fit

- if too hard for you with your fingers to press the gears onto the half axles, take the assistance of a drill press or similar

 

 

[attach:fileid=/sites/model-railroad-hobbyist.com/files/users/Rasselmag/DSC02995.JPG]
[dsc02995x4kxk]

- check gauge and correct if necessary

- refit the wheelsets into the trucks

- snap on the gear cover

 

This is the most effective method to repair older P2K loco with cracked gears. Also the fastest and most robust one.

 

Lutz

Edit: Photos reattached
Reply 8
railandsail Prolific poster 8,858 posts
railandsail

I wouldn't suggest you throw

I wouldn't suggest you throw all those cracked gears in the trash right away,...perhaps put them in a particular bag labeled 'bad gears'.

I'm suggesting this because its my understanding there are a variety of Proto 2K gears that are not necessarily replaceable with the Athearn gears. So where, or can, we get replacements for them?  And how about some other brands that might have similar problems?

I'm thinking we may find a way to resurrect some of the odd-ball ones that don't readily have replacements.

 

 

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
Reply 1
bno4333 New member 13 posts
bno4333

Also...

I also used calipers to make sure the gear is centered and used the opportunity to clean the whole tower assembly. Before re-installing the new wheels, I painted and weathered them. Makes it easy to tell which engines have been upgraded.

 

Roger
Reply 5
Rasselmag Frequent poster 539 posts
Rasselmag
Photos are gone,
so i reattached them in the first posting.

Lutz
Reply 2
railandsail Prolific poster 8,858 posts
railandsail

Gluing Gears Experiment

Quote:
First you need to get the primer into the crack - a "thin" ACC like the pink Pacer simply gives you the best chance of getting ACC into the crack that will then bond the the plastic in the crack after the primer has done its work. The Loctite Plastic Bonding System that I mentioned in my previous post is similar to what I used and gets you both the primer (aka Activator) and the matched ACC glue in the one package.

John Garity      



I was in my local HD a few weeks back and read the label on this Loctite product that John mentions. It specifically claimed it 'fuses hard to bond plastics". The price was very reasonable, so I thought why not give it a try.

My first trial was gluing back some faulty designed plastic trucks supplied with twin stack container cars. It worked to a degree, but was not acceptable in the long run. It was NOT thin enough to wick into all the areas I was hoping to get covered,...plus the finished truck still allowed for too sloppy of an axle fitting.

My second trial was on a Proto 1000 c-liner, the B-unit. All 4 axles were cracked. I soaked them in mineral spirits in hopes of removing all oil and grease residue that might be on them,...then let them dry out for a day,..then blew a little compressed air over them. I removed the snub metal axles from the gear, then inserted a slightly large flat blade screw driver into the plastic gear to open up the crack a little bit bigger. I then tried my best to coat those inner crack surfaces with the primer in that Loctite kit.

Next I coated those inner surfaces of the crack with the bonder using a small toothpick. Clamped the gears together with paper clips and left them set up overnight. Then I took a small drill and hand reamed the hole out to provide a press fit for the metal snub axles. IT WORKED.

There was a couple of them that were just a little loose as to allow the axles to turn inside the gear (guess my drill reamer was just a tad too big). No problem, I took the snub axle out and using my toothpick I put the slightest little of the same bonder/adhesive on the inside hole of the gear, then 'screwed' the metal snub axle back in while all the while keeping a check on wheel spacing. Left that set up overnight.

Yesterday I ran the loco and the clicking had disappeared. I also pulled 20 cars with it and no clicking yet. It remains to be seen how long this repair will work, but it appears possible to resurrect some of our old engines that may not have replacement gears available for them.

My next experiment might be with another super SUPER glue product that I had GREAT success with long ago.
Pasco Fix........    

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
Reply 2
Bernd MRH Author 5,629 posts
Bernd
railandsail wrote:

Gluing Gears Experiment

My second trial was on a Proto 1000 c-liner, the B-unit. All 4 axles were cracked. I soaked them in mineral spirits in hopes of removing all oil and grease residue that might be on them,...then let them dry out for a day,..then blew a little compressed air over them. 



Brian,

I would have soaked them in denatured alcohol. I believe mineral spirits leaves a residue behind when it dries. 

Here's what mineral spirits is:  "White spirit or mineral spirits, also known as mineral turpentine, turpentine substitute, and petroleum spirits, is a petroleum-derived clear liquid used as a common organic solvent in painting."

Bernd 


 

New York, Vermont & Northern Rwy. - Route of the Black Diamonds - NCSWIC
Reply 3
railandsail Prolific poster 8,858 posts
railandsail
I had those same thoughts Bernd,.. about NOT use mineral spirits for that cleaning action. That's all I had on hand at the time.

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
Reply 2
Rasselmag Frequent poster 539 posts
Rasselmag
Glueing these gears are feckless attempts.

Throw away cracked gears right into the trash bin and replace them with new ones.

Reasons:
# glueability of POM
# tensile strenght of Cyanacrylat
# available adherend
# press fit gear onto axle
# resulting inner tensile forces
# uncorrect meshing of gear
# useless amount of work
# fitting new gears is just fewer amount of work
# you spare the glueing attempts
...
# at least do not kidding yourself
I live in a real reality and the glued gears will crack again just in the moment when you start to press fit them onto the axles. Natural laws of the real reality  are non discussable. 


Lutz
Reply 5
railandsail Prolific poster 8,858 posts
railandsail

Quote:
I live in a real reality and the glued gears will crack again just in the moment when you start to press fit them onto the axles. Natural laws of the real reality  are non discussable. 
Lutz


With my experiment I did not experience the gears cracking when I reinserted the axles. Perhaps that was because I did not ream out the holes so small that there was a LOT of pressure required to press the axles in,..in fact in a few cases my reaming was just a bit too large resulting in the gears slipping. I decided to try gluing those gears onto the axles as a precaution.

So far all 4 of my repairs are working.

I was not suggesting that this be an alternative in cases where the Athearn replacements are available. My concern is the cases where Athearn replacements are NOT available. I believe I read that the gears utilized on the Proto PA's is different,...and replacements are not availabe??

Quote:

https://cs.trains.com/mrr/f/88/t/276610.aspx

You can see by the Walthers wheelset (wheels plus gears) offering below (not always available) that the GP18s are included with the list of GP7s, etc.  I'm fairly certain that the Geeps use the Athearn ATH60024 gears (re-use the wheels & 1/2 axles) that Athearn is showing as SD40-2 replacements.

https://www.walthers.com/replacement-geared-driver-assembly-diesel-wheelset-pkg-2-for-early-proto-2000-r-bl-fa-gp7-9-18-20-30-60-proto-1000-tm-f3

http://www.athearn.com/Products/Default.aspx?ProdID=ATH60024

I have used the Athearn gears on a number of LL locos that I have procured & converted to DCC.  Always count the gear teeth, though, to be sure you do not have another gear need.   For example, my LL E6s (a less common problem but it can occur with the 6-axles diesels) required a different gear tooth count, see the next item for those.  And I believe there are other variations such as non-centered gears and/or a 3rd tooth count for a few of the LL's.  But you should be safe with the Athearn gears for your GP.

https://www.walthers.com/replacement-geared-diesel-wheelsets-fits-early-proto-2000-r-e6-7-8-9-pkg-3



[26201570368_0102efafe5_o] 

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
Reply 3
Bernd MRH Author 5,629 posts
Bernd
I've always thought that maybe using a reamer, not a drill, but an actual reamer, be it imperial or metric, a small amount, like maybe .005" or .1mm smaller than the axle be used to ream the new gear set or the old one if the gears haven't cracked yet. Then use a bit of Locitite and lock the gears on the axles.

Bernd

New York, Vermont & Northern Rwy. - Route of the Black Diamonds - NCSWIC
Reply 2
Prof_Klyzlr Moderator 7,962 posts
Prof_Klyzlr
Quote:
if the gears haven't cracked yet.


Yeah, catching them before they crack is the hard part of that procedure... :-(  ;-)
(and, let's be honest, very very few contemporary modellers want to take a loco apart before  there's a "call to action" problem or symtom evident...)

Happy Modelling,
Aim to Improve,
Prof Klyzlr
Reply 2
Rasselmag Frequent poster 539 posts
Rasselmag
Next case:

[dsc0346776je0]
Oh it's cracked! Put some super-duper glue on it an carry on.
A not so effective idea.


The prehistory:
[dsc034544mjxq]
This gear is the main axle gear of an Bachmann-Spectrum 1:20.3 Scale 2-8-0 with model weight about between 5 - 6kgs.



[dsc03459e7kj9]

[dsc03464vmjlw]
The amount of worf for removing and dissassembling of the drivers have much in common with the real prototype.
And now glueing it?
No botching here! The customer wants a durable repair of his loco.



[dsc03516mnjtp]
As the original spare part was unavailable at Bachmann Trains while i was doing the repair,  the solution was to order a gear from an independent supplier. Sending technical data about the spur gear to him he was able to fabricate a new gear to my specifikations, but this time i choose to make it out of brass. I choose a tight press fit onto the axle so this spur gear is able to take the immense driving forces of this G-Scale loco.
This repair done properly will last a life long.

When i write this post today, the part is available by Bachmann again. https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_142&products_id=10285
And as you can see, Bachmann changed the material of the spur gear to brass too.


Lutz
Reply 3
railandsail Prolific poster 8,858 posts
railandsail
That's good thing that the manufacturer came up with a repair gear for their originally faulty gear !


Yesterday I was watching a video on the original, older Mercedes 300 SL. Mention was made that someone could STILL get replacement parts for these cars that were built in 1954-55 9from the manufacturer.  I owned a 1973 450SLC for a large number of years, and I experienced a break  in the front suspension subframe. Turns out it was a manufacturers fault that had been found a few years after original production. Very surprisingly Mercedes replaced the whole unit up there,...under warranty,...  something like 20 years later.

That is service that has disappeared in this modern age, were you are lucky to get warranty parts for a product that is only months old !!

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
Reply 3
railandsail Prolific poster 8,858 posts
railandsail
Just found this example of a 10 year history of glued axle gears to metal shafts,..

Quote:
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... [smile] )

Happy Modelling,
Aim to Improve,
Prof Klyzlr

https://forum.mrhmag.com/post/repairing-gears-on-truck-axles-12206700?highlight=cracked+gears&pid=1331203400

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
Reply 2
railandsail Prolific poster 8,858 posts
railandsail

Possibly a third candidate for gluing these gears??

https://www.micromark.com/Poly-Zap-1-2-oz-

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
Reply 2
railandsail Prolific poster 8,858 posts
railandsail

Adhesives for Delrin

https://www.reltekllc.com/adhesivesfordelrin.aspx

RelTeck

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
Reply 2
Juxen Super User 576 posts
Juxen
I've got a Stewart U25B up on the blocks for new gears. I tried the 60024 Athearn ones, and the fit is too small. I milled out the gears to the correct width for the axles, then tried to fit them. Not sure why the running gear runs worse, it could be interference from a longer tooth or something.

Since I've got an SLA printer now, I decided to print new gears (yesterday). Protip: If you try printing fine mechanical parts, don't waste the 6 hours like I did by accidentally leaving the anti-aliasing on. I'll have to reprint these tomorrow evening (printer booked through then), and try those on the U25B.
Reply 2
Rasselmag Frequent poster 539 posts
Rasselmag
Got this loco from a customer:

[dsc03398nikmj]
He has sucessfully glued the cracked gears. Bachmann H0 Climax, motor is humming, nothing moves, but make the loco running great again.

Glueing was indeed very succesfully done here.
Any ideas?


Lutz
Reply 3
Rasselmag Frequent poster 539 posts
Rasselmag
Hello,

the 2-truck Climax i could save by mounting two new trucks ordered from Bachmann, a rather expensive repair for the owner. As written, glueing was very sucessful done by the owner of the model. Both trucks were fixed into solid blocks, nothing rotated any more.


Got another Climax:
[dsc05234mskan]
This time a 3-truck.




[dsc052356sjsx]
The trucks are simple demonted, they have a simple snap on mounting.
The middle truck was also extreme sluggish, the two other ones were blocking at one point. A sign that there are cracked gears.




[dsc05236uuk5x]
Removing the bottom cover plate, before you have to demount the brake beam.



[dsc05238ask48]
And yes there a cracked bevel pinions. The cracks are hard to see, you will need a magnifying  glass like those which watchmakers are using.




[dsc05239h0je7]
For this the cracked bevel pinions were cut in halves and thrown into the trash bin for not fooling you any further.




[dsc05237oqj3e]
The middle truck was extreme sluggish. Why i asked and found glue on a pinion.  As super glue has a extreme low viskosity, it creeps into all small seams and gaps. So here into the very small gap between drive shaft and bearing. Thus what is was intended for, glueing effectively shaft an bearing together. The drive shaft rotates still, but only because the bearing for the shaft is rotating in it's seat.  🙄
New drive shaft and new bearing additional necessary.




[dsc05240p0kz1]
And here is the trick:
The drive shafts have a shoulder which has 1.2mm in diameter and it is knurled.
The bore of the new pinions have a inner diameter of 0.9mm.
You can press fit with high force onto the 1.2mm knurled shaft.
It will fit, but it is from the beginning under a high internal tension force. The danger that i will crack in the future again is given.
To attenuate the tensile forces to a reasonable strenght, i bore the new pinions with a 1.2mm drill bit. Plastic is also elastic and so the real inner diameter after widening it with a 1.2mm drill bit is not 1.2mm as you expect with steel or brass. The plastic is widening while drilling and after teh drill bit is removed, it rebounds. It will press fit still onto the 1.2mm shaft and the knurling will do it's own.
This eases the inner tension and left more than enough tight fit to fix the pinion onto the shaft. 




[dsc05241n5kjo]
When all cracked pinions are replaced remount the trucks. Put the onto the workbench and and shove them without adding any pressure. They have to move easy and without any binds unter their own weight.
Is this o.k. then you can remount them.



As with Bachmann Climax, there is another bugbear to deal with:
[dsc03836l7j6e]
Deep hidden in the center gear there is a spur pinion which was made out of plastic. This is prone for cracking too.  And here too, no messing around with glueing attemps, replace it with a brass one. 10 teeth, module 0,4 and bore for press fit onto 1.5mm shaft.




[dsc03396pwkb1]
But fortunately only the first runs have these plastic gears. Later runs have a pinion made out of brass and this lasts.




[dsc05243f0kht]
And it runs great again.


Lutz

Meanwhile i have repaired several dozen of this geared steam loco models
Reply 5
MikeHughes Super User 5,583 posts
MikeHughes

Bachmann seldom does anything to improve my opinion of their mechanical quality.  

Consistent since 1883 !
[MRH%20Sig%202]Mike’s Index and Blog
Reply 3
Prof_Klyzlr Moderator 7,962 posts
Prof_Klyzlr
MikeHughes wrote:

Bachmann seldom does anything to improve my opinion of their mechanical quality.  

Consistent since 1883 !

... um, comparing the new-era HO 44, 45, and 70 tonner centre-motor units to the older dual-motor units, there certainly has been marked improvement in some areas...

...and their N scale offerings of today rip all over the 80s/90s era efforts.. 

Happy Modelling,
Aiming to Improve,
Prof Klyzlr
Reply 3
railandsail Prolific poster 8,858 posts
railandsail
Sure wish that gentleman that was so instrumental in bringing out many of Bachmann's new products was still with us,...alive that is. I'm sure he would be solving some of these problems.  (sorry I can't recall his name at the moment)

Great pics and explanations Lutz. (BTW I don't think I would be trying to glue those 'so little' bevel gears)

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
Reply 2
Prof_Klyzlr Moderator 7,962 posts
Prof_Klyzlr
Quote:
Sure wish that gentleman that was so instrumental in bringing out many of Bachmann's new products was still with us,... (sorry I can't recall his name at the moment)


That would be Lee Riley, RIP...
Reply 3
joef MRH Founder 17,567 posts
joef
I’m not so much interested in these niche glues for gluing plastic gears or any part that will take mechanical stress. But I am interested in glues for odd plastics that I could use other places in my modeling such as to repair broken plastic detail parts. So keep the niche plastic glues coming. MRH will collect them and do a bake off to see which ones work the best.

Joe Fugate​
Publisher, Model Railroad Hobbyist magazine

[siskiyouBtn]

Read my blog
Reply 4
Don Mitchell donm Super User 879 posts
Don Mitchell donm
Poly-Zap is specified for use on "Lexan, Delrin, Nylon, Polycarbonate & Rubber."  I used it to fix one of those infamous split gears.  It's held up so far, but hasn't accumulated enough running time to be considered a certain fix.

Don Mitchell

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Read my blog
Reply 4
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