Atlas Motor Problem

[jeffstri]

I've done a bunch of these in swapping out older high speed motors for scale speed ones. I push both flywheels on by hand, then put the motor and flywheels between the jaws of a small vise, and slowly press the flywheels on. Its easy to align the setup so the flywheels go on straight, and the pressure is only on the ends of the motor shaft, not on the bearings. One of the flywheels usually goes on a bit too far so I use a wheel puller to adjust it.

[mmagliaro]

Peteski, what he said.

I put both flywheels on by hand, then press between the jaws of a jewelers vise.  They usually move evenly.
And as a flywheel gets pressed further and further down a shaft, it gets harder to move it, so the process kind
of evens itself out as you go.  That is, if one flywheel gets a little ahead of the other, and is further down the shaft,
that one doesn't move as easily anymore, so the other one kind of "catches up".

But yes, once you get in close, if one is a little too close, a gear puller will pull it back out a bit.  Once they've been pressed off and on one time, they are not as hard to move with the gear puller anymore.

On the motor in question, I just put both on and pressed, and they came in very evenly.

A note of caution for anyone who may not realize it.  If one flywheel gets into position before the other, and you
don't want it to move, do NOT put any kind of temporary spacer between that flywheel and the motor housing to keep it from moving.  If you do that, you will start putting pressure on the housing, not the flywheel/shaft, and then the shaft
could move inside the housing and destroy the motor.

If you are really having trouble getting the flywheels to come in even, then do this.  When one of them is all the way down as far as you like it, take the motor out of the vise, and put a short piece of 1.5mm shaft material into the end
of the hole on that flywheel, so it sticks out past the flywheel.   Put the assembly back in the vise so that on that end, you will be pressing on that piece of shafting that is sticking out (instead of the flywheel).  Now you can press the second flywheel to your heart's content, and the first flywheel won't move because you're not pressing on it.  The short piece of shafting will not be hard to pull out when you are done, as it will just barely be into the hole in the end of the flywheel.

[peteski]

Thanks guys - now we have a complete flywheels removal and reinstall well documented. 

[davefoxx]

Results before
Motor A: 58 smph
Motor B: N/A

I received the motors back from @mmagliaro and @peteski yesterday and today, respectively.  I reinstalled Motor A and its top speed is 57 smph in one direction and 59 smph in the other direction, and it will run steady at speed step four at a mere 1.3 smh!

I haven't swapped motors to test Pete's tonight.  Give me a day or two to tear down the locomotive and install Motor B.

DFF

[mmagliaro]

I received the motors back from @mmagliaro and @peteski yesterday and today, respectively.  I reinstalled Motor A and its top speed is the same: 57 smph in one direction and 59 smph in the other direction.  However, the low end is much improved.  It will run steady at speed step four at a mere 1.3 smph!

I haven't swapped motors to test Max's tonight, but I expect much more dramatic results.  That motor didn't run well at all when it left here last week.  But, give me a day or two to tear down the locomotive and install Motor B.

DFF

Wait, are your letter codes right?  I thought Peteski's was the one that wouldn't run at all.  Wouldn't that be motor "B" in your list?

[davefoxx]

Wait, are your letter codes right?  I thought Peteski's was the one that wouldn't run at all.  Wouldn't that be motor "B" in your list?

Oops, you're right.  I forgot that I switched the motors before I shipped them.  The installed motor tonight was yours.  I'll edit my previous post.   

DFF

[mmagliaro]

Oops, you're right.  I forgot that I switched the motors before I shipped them.  The installed motor tonight was yours.  I'll edit my previous post.   

DFF

Thanks, Dave.  And your in-engine behavior agrees with what I saw on the workbench.  The motor ran, and it did not seem slow to me.  But it wasn't steady in it speed and it wouldn't start quite as slow as I would have expected.  Those two things improved after I cleaned out the armature slots. 

Now... the thing to watch.  There's got to be a reason that those armature slots loaded up in the first place.  Either that motor has simply been run for a lot of hours, or it was run under excessive load, or there was some sort of defect in the brush material that made it too soft and caused it to deposit a lot of dust into the slots.
If you decide to keep the motor in service, we'll find out soon enough if the fix is short-lived (if the slots are going to just load up again).  My experience with these Atlas and Kato motors over the years is that they usually outlive the engine they are in.  But then, I do not run my engines hard on a club layout week after week. 

[peteski]

Another possibility: Too much oil in the bearing adjacent to the commutator can cause oil to ooze out into the commutator. That oil film will make the powder from the brushes wearing down to stick into the slots in the commutator.

[davefoxx]

Another possibility: Too much oil in the bearing adjacent to the commutator can cause oil to ooze out into the commutator. That oil film will make the powder from the brushes wearing down to stick into the slots in the commutator.

I'm careful with oiling.  I generally don't until there's noise, and even then, it's usually only a drop.  However, I suspect that @peteski could be onto something here, because there have been times where it's been difficult to get the tip of my oil bottle between the flywheel and motor.  Under those circumstances, it's difficult to get that one drop just in the right place, so I will admit that it's possible that too much oil could have gotten in there.

DFF