Newer Atlas SD50 Drive Train Noise--Bearing Block Slop

[busdriver]

Hello,

I have read several threads about the various tricks for quieting Atlas locomotives.  However, I have not seen anything on this particular issue.  I have one of the new ESU LokSound SD50s from Atlas.  They are split frame held together by end clips at each end of the frame.  I am getting a serious clickity clack that almost sounds like wheels over joints, but that is not the source.  The BEMF also seems to kick in with the clicks causing "jerking."  I took the trucks off of the loco, and there is a ton of left to right play in the bearing blocks on either side of the worm gear.  Unlike the previous version, there is no small brass clip with the sprung prongs to hold the blocks to one side.  These are free to flop left and right, and I think that may be the source of the noise.  I do notice that when there is a load on the engine, the noise is greatly reduced. 

What is the best thing/method to shim those blocks so they can't move around side to side?

Would the spring in the flywheel fix be a good thing here?

Thanks.

Bryce

[peteski]

Hello,

I have read several threads about the various tricks for quieting Atlas locomotives.  However, I have not seen anything on this particular issue.  I have one of the new ESU LokSound SD50s from Atlas.  They are split frame held together by end clips at each end of the frame.  I am getting a serious clickity clack that almost sounds like wheels over joints, but that is not the source.  The BEMF also seems to kick in with the clicks causing "jerking."  I took the trucks off of the loco, and there is a ton of left to right play in the bearing blocks on either side of the worm gear.  Unlike the previous version, there is no small brass clip with the sprung prongs to hold the blocks to one side.  These are free to flop left and right, and I think that may be the source of the noise.  I do notice that when there is a load on the engine, the noise is greatly reduced. 

What is the best thing/method to shim those blocks so they can't move around side to side?

Would the spring in the flywheel fix be a good thing here?

Thanks.

Bryce

Yes, the chassis is redesigned (new and improved).    I have not played with it.
I replied  because I'm curious about the spring in the flywheel trick. Never heard of it.  Details please.

[u18b]

Yes, the chassis is redesigned (new and improved).    I have not played with it.
I replied  because I'm curious about the spring in the flywheel trick. Never heard of it.  Details please.

That might be an old idea and from me.   
Probably originally from the Atlas forum days.

I had an old SD50 that had a lot of lateral linear slop in the worm.

I placed a little coupler spring on the hex nut.
It worked, but probably not the best solution.

There are a lot more thrust washers made now which could take up some of the space between the worm and the bearing block- if needed.

[tehachapifan]

For clarification, are we talking about linear worm slop or lateral worm slop? Linear meaning front to back in relation to the loco frame and lateral being side to side in said frame.

[busdriver]

It's lateral slop.  They move a couple of mm side to side.

Bryce

[busdriver]

Hey Peteski,

I see you everywhere 

Here is the rather interesting thread where I saw the spring and other ideas. The spring idea is called the Bearden Fix from what I'm gathering.  I heard his name mentioned several times in the threads I read.

https://www.therailwire.net/forum/index.php?topic=40758.60

Bryce

[peteski]

Yes Bryce, I'm an AI bot participating in multiple online venues.     Thanks for refreshing my memory.

Couple of millimeters seems like a lot.  The thickness of the worm gear is probably about 1mm. If the worm could move laterally couple of millimeters, it would be close to losing contact with the worm gear.

Spookshow's site https://spookshow.net/loco/atlassd5060.html shows one chassis half.


Looks like  the worm bearing retainers on that half look similar to the old Atlas/Kato design.  If there is not springy insert to keep the bearings Atlas probably just molded some protrusions to keep the bearing in place.   Maybe you could glue some styrene shims there to reduce the lateral play? Not ideal, but it might do the job.

[busdriver]

Peteski,

Yes, the other half has protrusions that are intended to "meet" the exposed side of the blocks.  I'm not really a metric guy, so I just looked at my ruler in my desk to remind me what a mm looks like.  It is probably slopping 1mm laterally.  It is a LOT compared to what I'm used to when there is a clip with prongs which is nothing unless force is applied.  I was thinking some sort of shim as well, but I hate gluing things.  I wonder if a thin rubber or foam shim would work and allow for some movement/flexibility.  I just have to be sure it doesn't pop out and cause more drama.

When I take it apart again, I'll see if I can get some pics and a movie.

I'm thinking the Bearden fix might work with this since it will put a little pressure on it to maybe keep it from vibrating.  Since it is quiet when in consist or pulling a train, a little pressure may be the easy fix.


Bryce

[peteski]

Gluing anything to the white metal loco frames is not absolutely permanent, either using super glue or epoxy.  Whatever you glue on can be pried off and the remaining glue can be cleaned of fairly easily.

I agree that using some sort of flexible or elastic material to push against the bearing block seems like a good idea. That's what those springily contacts did in the older versions of the chassis.  If you are planning on gluing a slice of rubber band keep in mind that after few years the rubber might dry up and become hard and brittle.

Also heads up  about uploading photos. You need 25 posts under your belt. See https://www.therailwire.net/forum/index.php?topic=43673.0 .

[busdriver]

Thanks for the reminder about not being qualified to put up videos yet.  I put it up on Youtube.  Sorry the quality isn't clearer.  I only had 2 hands, and 3 things to try to hold/control   

https://youtube.com/shorts/AltVNxTU0h8

I did go ahead and try the Bearden fix.  It definitely helped with the longitudinal movement.  I also put small pieces of soft white rubber band material that I had around in the bearing block slots.  It stuck well enough in the grease that is in there.  Atlas definitely over lubes these things.  I pulled out a bunch of grease.  That solved the lateral movement. I would love to put up some pictures, but that is apparently still not allowed.  I need to be more active .

Ultimately, it still makes quite a bit of clickity clack when running.  Not sure what is causing that.

I saw in a post somewhere that someone swapped out the Atlas Axles for Kato Low-Profile Axles.  I had some of those lying around, but they are a little bit longer in the axle.  The truck frame did not want to go over it, so I gave up on that idea.  How was that done if anyone knows?

Bryce

[peteski]

It is not a mystery.  As I mentioned in my previous post, you need 25 posts to be able to post photos.  Looking at your post count (on the left side of any of your posts) you have 14 posts under your belt. 

Kato Diesel wheelsets have axles slightly longer than Atlas.  They will fit, but will be a bit tight in the bearing cups (so they will not roll as freely as they should.  There is a lengthy thread about this retrofit: https://www.therailwire.net/forum/index.php?topic=33107.0 .  The useful info on doing the retrofit properly starts around https://www.therailwire.net/forum/index.php?topic=33107.msg596466#msg596466

There sure is a lot of lateral play in those bearing blocks! Hopefully the rubber inserts will do  the job for you.  As far as the clicking sound goes, could there be some debris (like a grain of ballast) stuck in the grease between some gear's teeth? As you observed, manufacturers use way too much grease in their models!

[woodchip]

I was going absolutely bonkers trying to figure out what was wrong with an original frame SD60. Took it apart put it back together repeatedly, nothing. Then I found this post from the Railwire about how these tiny almost unnoticeable tabs can break off. I think the only change on the trucks is that they now have wires attached to the tabs where the contact strips made contact. Here's the link to the post. if it doesn't go direct to the page it can be copied and pasted.      https://www.therailwire.net/forum/index.php?topic=45032.msg581969#msg581969

[NtheBasement]

When I read the description in the OP my immediate thought was that there is something granular (like ballast) caught in one of the gears on one of the trucks.  Test: take off the trucks.  Roll your finger over the top gear and get it to turn.  Does it feel smooth, or is there some point where you can feel the resistance bump up?

[busdriver]

Hey Peteski,

Yep, I was trying to be cute (unsuccessfully) with my comment about not being able to post photos since I haven't posted enough.  I'll try to spread out my responses to up that count .

[busdriver]

Also, thanks for the link on the Kato axles upgrade topic.  I will take a look at that.

Bryce