Atlas 540104 Universal Cracked

[johnh35]

I am finding more and more of these universals cracked on my Atlas lokies and haven't been able to source replacements. IIRC, Atlas just made another run of the FM H15/16 which use this part but still do not have any in stock. Has anyone found a viable replacement that doesn't alter the motor shaft? With IM and Atlas both using this part I'm dumbfounded as to why replacements have been unavailable for quite some time. Maybe they need to look at manufacturers in the US. I don't mind paying a little more versus my stuff sitting on a shelf.

[randgust]

Had to look this up on Spookshow, and sure enough Mark has a diagram posted.   Is this the little nub that is inside the flywheel stuck on the shaft end?  Seems to me that's used in a number of units.
See http://www.spookshow.net/loco/atlash1516.html


I had the problem with the C630 and successfully changed everything over to NWSL universals (steel shaft and nylon cups) but that's on a completely different shaft and cup system.   

[Dirk Jan Blikkendaal]

had the same problem on several Atlas motors......
the most simple/effective/cheap/quick replacement is as follows:
drill two small holes halfway the flywheel (lengthwise) opposite each other, pointing towards the motor shaft.
I made a flat spot with a small file first to get the drill started easily.
insert slightly smaller size steel wire (with some ACC on it) into both holes with the steel wire touching the motor shaft.
using a grinding disk on your motor tool cut off all excess steel wire outside the flywheel.
before drilling/filing/grinding use simple plastic tape to cover the motor completely to avoid small metal particles entering the motor.
a little off center is no problem.... can easily be corrected by slightly enlarging the slot on the universal shaft.
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[johnh35]

I've seen that solution before (I think you posted it previously) but my only concern is that the superglue might not hold and the pin would slip out and wreak havoc. I may try the NWSL route. Has anyone had any experience with these? https://www.shapeways.com/product/2XA8RXZWU/replacment-atlas-n-scale-male-universal-x4?optionId=163572979&li=marketplace

[Hedron]

I've seen that solution before (I think you posted it previously) but my only concern is that the superglue might not hold and the pin would slip out and wreak havoc. I may try the NWSL route. Has anyone had any experience with these? https://www.shapeways.com/product/2XA8RXZWU/replacment-atlas-n-scale-male-universal-x4?optionId=163572979&li=marketplace

Been looking at those myself, as I've encountered the same split universals several times in some "not-running" lots I've bought. One C-628 was new/old stock and apparently cracked on the shelf.

Here's what the designer of the Shapeways replacement says about it: https://jamesmodelrailwayco.com/2020/05/26/replacement-atlas-n-scale-motor-universal-connectors/

[brokemoto]

I had an Atlas FM road switcher go sour on me.  I was surprised.  Only one truck had moving wheels.  The other one did not.  I wonder if the problem described by Original Poster and others was the one that I was having.  I bought another one, swapped the shells and sold the bad one on FeePay as junk (I was surprised at what it fetched).  Spookshow states that it was early runs of this one.  Has this problem shown on later runs?  My replacement FM is still running well.

[dandopinski]

Briggs Models make a replacement universal for the Atlas C series locomotives. I've installed them in 3 of mine and they run just fine

[Dirk Jan Blikkendaal]

I've seen that solution before (I think you posted it previously) but my only concern is that the superglue might not hold and the pin would slip out and wreak havoc. I may try the NWSL route. Has anyone had any experience with these? https://www.shapeways.com/product/2XA8RXZWU/replacment-atlas-n-scale-male-universal-x4?optionId=163572979&li=marketplace

I sure did post it before and my "rebuilts" run for years already..... never had a loose pin... use almost same diameter drill as steel wire (tight fit) and good ACC (a bit too much).... if by chance a pin would come loose it would block the motor from turning right that moment (thus stopping train directly) and would cause no damage if track power is not left on for ages...... 

James Norris is a good designer but the Shapeways material (which I use a lot) is just not as tough as steel (gets even quite brittle in my opinion after cleaning) and long term durability is just as uncertain as the original part.....

Its simply a weak design from Atlas... such a small plastic part taking quite a bit of strain/force on a slick steel shaft......

[Lemosteam]

@Dirk Jan Blikkendaal , brilliant solution, and IMHO, steel wire is overkill .  The wire is so short, there will never be enough torque load to bend or break it, the U shaft would twist apart first.  0.030" brass wire could be soldered in flywheel holes instead of using ACC and so would never come out.

[peteski]

@Dirk Jan Blikkendaal , brilliant solution, and IMHO, steel wire is overkill .  The wire is so short, there will never be enough torque load to bend or break it, the U shaft would twist apart first.  0.030" brass wire could be soldered in flywheel holes instead of using ACC and so would never come out.

I also agree that steel wire is not necessary (brass would do fine), but in order to solder the wire properly, the solid-brass flywheel (basically a large heat sink)will need to be heated up enough for the solder to melt and wet its brass surface. That will take a large iron and some time.  I would be worried that all this heat might negatively affect the motor armature or commutator (since the motor shaft will also get hot.  Otherwise you end up with a cold solder joint where the solder just sits on the surface of the flywheel.  Maybe using one of the low melt point solder alloys would work.

[rrjim1]

If I ever had a problem with mine, and I have several. I would make them out of Delrin and use loctite 680 retaning compound. The 680 holds 1000 times better than super glue.   

[C855B]

I've got an SD24 and a C630 sidelined with cracked universal donuts. The problem I have with replacing them is... I can't find my stash!. Knowing this was a bug with this design, I stocked up several years ago. They're there somewhere, just under several layers of projects on my work tables.

Anyway, aside from doing an overdue cleanup, I think my short-term and long-term solution is similar to James', draw one up in CAD to print out on my Photon and call 'er done. If I do that I'll share the artwork.

[Maletrain]

Does Locktite hold on Delrin?!

[robert3985]

I've seen that solution before (I think you posted it previously) but my only concern is that the superglue might not hold and the pin would slip out and wreak havoc. I may try the NWSL route. Has anyone had any experience with these? https://www.shapeways.com/product/2XA8RXZWU/replacment-atlas-n-scale-male-universal-x4?optionId=163572979&li=marketplace

Regarding Shapeways Atlas Universal replacements:

Yeah.  I bought these to fix my buddy Nate's FM H15-44/H16-44 since I couldn't find any Atlas replacement parts. This part looked promising, but I had my doubts about it since the FUD it's printed in is, in my experience, pretty brittle.

So, they arrived and I had to squint hard to see 'em, took one off the support structure and made sure the hole through it was unobscured and developed a method to press it on to the shaft.

To make a short story even shorter, I cracked three of them before deciding they weren't going to work using various methods to achieve a secure, tight, press-fit on the steel shaft.

So, I don't recommend them.

The problem got solved a month later whilst rubbernecking around at the NMRA show when I happened upon a fellow who had a sh!t-pot full of Atlas spare parts for sale on his table.  Since I have two of these engines, and I inherited four of Nate's, I got an even dozen of these along with some GP-7 and GP-9 parts...went home that evening and it took me about 20 minutes to fix the problem with genuine Atlas parts.

So, I'm prepared for future breakage.

Cheerio!
Bob Gilmore

[Lemosteam]

I also agree that steel wire is not necessary (brass would do fine), but in order to solder the wire properly, the solid-brass flywheel (basically a large heat sink)will need to be heated up enough for the solder to melt and wet its brass surface. That will take a large iron and some time.  I would be worried that all this heat might negatively affect the motor armature or commutator (since the motor shaft will also get hot.  Otherwise you end up with a cold solder joint where the solder just sits on the surface of the flywheel.  Maybe using one of the low melt point solder alloys would work.

For a true solder joint yes, but to provide some quick interference on the pin, you could tin it first, press it in and hopefully melt some of it with flux and a quick hit with the iron.  It's not like the motor is spinning quick enough to send the pins flying out. It really does not take much contact.