IM SD40-2W with split male universals proof on concept fix

[Steveruger45]

As many know this loco and some Atlas locos like the C628/630 use motors with extended shafts inside the flywheels onto which that little male universal Is press fitted and often fails/splits.
It so happens i had one i de-motored and use as a dummy loco Plus i had a whole bumch of old removed Atlas parts including the more usual atlas motor with flywheels with the hexagon holes.
So i thought why not try to see if i could get it going by swapping out the drive.
In short, i did the following:-
1. Put in an atlas motor with flywheels with the hexagon holes.
2. Used the original worms, bearings and ball joints.
3. Used the long intermediate universal shafts from an atlas SD60 to mate the motor with the worms.
I had to trim about 1 mm off each hexagon end of these universal shafts to prevent binding.

N scale IM SD40-2W repair, split drive universals. Proof of concept.

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[mat82]

Nice project.
I have two SD40-2W that run like crap.

Can you add the Atlas ordering numbers for the motor and the other parts?
I want to update my locos, too.

Tank you 

[Steveruger45]

Nice project.
I have two SD40-2W that run like crap.

Can you add the Atlas ordering numbers for the motor and the other parts?
I want to update my locos, too.

Tank you 

Hi @mat82
Here is a link or two from Atlas website in this post For Sd50 and C630.

https://www.therailwire.net/forum/index.php?topic=50367.msg678542#msg678542

Im not sure which Atlas loco the motor came from exactly, It was in my used parts box for quite some time, but it was probably a Classic GP40.  Atlas used the same motors in many many locos so the one from an SD50 or Sd60 would work too.
If you dont want to change the motor with flywheels the male universals that split are shown on the C630 link. They are the same as the ones used in the IMSD40-2W.  But they do suffer from the same problem of splitting too.  If you go that way get a whole bunch of those male universals.

Heres the direct link to Atlas website
https://shop.atlasrr.com/c-1064-n-locomotive-spare-parts.aspx

Heres a direct link to all the Atlas parts diagrams.
https://shop.atlasrr.com/t-partsdiagrams.aspx

[randgust]

Last year at Altoona I had a two-unit lashup of my LL C424 and an Atlas C630 running on T-trak and it mysteriously kept getting stuck.   I pulled it, boxed it, forgot about it.   This thread made me pull it out, wondering.

Yup.   Front truck is working slowly, rear truck is full speed, split universal somewhere on the C630, it's slipping.

So I'm following this with interest after discovering that you can't figure out which part is which on the Atlas website as there are no pictures.   And if there's a part list/diagram for the 630 I can't find that either.  There have to be better photo threads on this somewhere in Railwire, did a search and came up empty.

I'm wondering if I can simply take the 'horn' of an NWSL universal set (that has  that "D" shape hole) and fit it to the Atlas worm shaft, but that's probably too easy.    So before I wander down that path less taken, have any more information on your approach?  Photos?  Part numbers?

Here's the NWSL part, 2mm shaft, the ball pieces have a D shape hole that you have to grind the shaft down to fit, but easy with an abrasive disk and they never, ever slip.   http://store.blueoxtrains.com/nwsl-2-0mm-driveline-shaft-u-joint-s-489-6/
Chris 333 used that on his original tender drives and I've done it three times since then including on my latest 4-4-0 project.

[spookshow]

Here's the original parts diagram for the Alcos (it's on my website) -



-Mark

[randgust]

Thanks Mark, that confirms my suspicions about what's in there, and that the male ball joint is what's failing (49003)

[Steveruger45]

Last year at Altoona I had a two-unit lashup of my LL C424 and an Atlas C630 running on T-trak and it mysteriously kept getting stuck.   I pulled it, boxed it, forgot about it.   This thread made me pull it out, wondering.

Yup.   Front truck is working slowly, rear truck is full speed, split universal somewhere on the C630, it's slipping.

So I'm following this with interest after discovering that you can't figure out which part is which on the Atlas website as there are no pictures.   And if there's a part list/diagram for the 630 I can't find that either.  There have to be better photo threads on this somewhere in Railwire, did a search and came up empty.

I'm wondering if I can simply take the 'horn' of an NWSL universal set (that has  that "D" shape hole) and fit it to the Atlas worm shaft, but that's probably too easy.    So before I wander down that path less taken, have any more information on your approach?  Photos?  Part numbers?

Here's the NWSL part, 2mm shaft, the ball pieces have a D shape hole that you have to grind the shaft down to fit, but easy with an abrasive disk and they never, ever slip.   http://store.blueoxtrains.com/nwsl-2-0mm-driveline-shaft-u-joint-s-489-6/
Chris 333 used that on his original tender drives and I've done it three times since then including on my latest 4-4-0 project.

Hi there,
I added the parts diagrams link to earlier post.
Here it is. https://shop.atlasrr.com/t-partsdiagrams.aspx
Change the motor with flywheels for 489100, this is he “slow” motor or 490100 is the fast motor.
Change the universal shaft for 490109 and trim down the hexagon end about 1 mm each.
No more splitting male universals 540104

[randgust]

Yikes, I pulled my 630 apart and EVERYTHING is split in that drive train, both the ball on the end of the worm and the male 'horn' inside the flywheel. Both ends.  All four pieces are split. I thought white gear disease was bad... 

But, I made a discovery, the 1.5mm universal sets from NWSL should work, part number is 487-6, that's what I've been using in my steam tender drives.   You have to have some 1.5mm shafting, you have to cut it to length and grind a "d" on one end of the intermediate shafts, that's pretty fail-safe.   All the Atlas shafts are 1.5mm.

Wow, way worse than I thought.

I was able to successfully order more parts from NWSL.  Whew.    I'll photo this when I get it assembled

[Steveruger45]

Glad you have found another way and therefore keep the original motor.
Yep, those ball joints do split and also on other atlas locos, ive had to change a few of them now, including all 8 of my B40-8’s.
What I did in an attempt to stop the new ball joints splitting was dress out the shaft hole before pressing into place, just enough to still keep a good interference fit it on the shaft but minimize the “splitting forces” if you know what i mean.  Often it was just to clean a little flash off.

[peteski]

Glad you have found another way and therefore keep the original motor.
Yep, those ball joints do split and also on other atlas locos, ive had to change a few of them now, including all 8 of my B40-8’s.
What I did in an attempt to stop the new ball joints splitting was dress out the shaft hole before pressing into place, just enough to still keep a good interference fit it on the shaft but minimize the “splitting forces” if you know what i mean.  Often it was just to clean a little flash off.

I have done the opposite (when the metal shaft is easily accessible).  I take some 320, or 400 grit sandpaper, wrap it around the shaft and sand it down a bit, until I can get looser fit of the universal (less stress on the plastic.  Bascially I run the motor (or chuck the worm shaft in a Dremel) while letting the sandpaper do its thing. Then I make sure to degrease all the parts, and superglue the universal onto that sanded shaft.  The sanded metal surface produces a stronger glue joint.

[randgust]

OK, so here's my fix - NWSL 1.5mm universals and shafting



There's one of the females pressed into the stub shaft inside the flywheel:



The 1.5mm steel shafting was cut with a dremel disk, wear eye protection.   It has to be ground to a "D" shape on the ends to fit into the NWSL ball, but that means that you're not relying on a squeeze fit to keep it from slipping.   Now, the delrin castings (particularly the femaie part) need to be trimmed for flash, and also reamed out to make sure the 1.5mm shaft fits just right.

Reassembled everything and it's working fine, nice and quiet, no more slipping, successful operation.   And thanks for posting this thread, although I have to admit I was rather shocked to find out how bad mine really was in there.

[Steveruger45]

An excellent “ Engineers” fix indeed.
Now you won't have your balls splitting anymore. 😉

[randgust]

I think just dropping in Atlas replacement parts would have been a lot easier, if they held up, were in stock, and could be identified on their website 'for sure' with pictures.   It's been pretty frustrating getting the right parts off that site.    This wasn't a mission-critical locomotive, heck, I haven't had it out of the box for a year so it was kind of exploratory surgery.   The 630 made the list of 'lightweights' in terms of performance (tractive effort) and has been in the display case since I got it.   At least it runs now.

[rrjim1]

Wonder why some fail and some don't? I have 4 C628s and 2 C630 and have yet to see any fail. I have had a lot of the Kato joints in the old atlas RS3/11 split. I just ream the new joint out and use 620 to retain them to the shaft. Works great and have yet to see one come loose.   

[randgust]

I thought I was pretty much exempt, or lucky - but I had a Bachmann Doodlebug literally drop it's wheels off from white gear disease, and now this, and really neither one was hardly ever run.   I keep watching my Kato NW2's and I've had a bunch of those and have never had one split, but you know what they say.

I was tempted to just try the 'clean and Loctite' here but that doesn't always work that well on Delrin, sometimes it does, and I had a stash of the NWSL parts.   My Atlas shaft and universal parts were just about dripping in lubricant, I didn't put it in there, and I'm half wondering if what's going on is some kind of lubricant reaction.   Back when I was just a kid I kept putting 3-in-1 oil on styrene model moving parts with the inevitable results, learned the hard way.    I don't know that anything kills Delrin except stress, but I'm no expert.