N Scale Atlas Shay - Dead Motor(?) and Removing Brass Flywheels/Worms

[DRailed]

Hello Everyone,

I bought an Atlas Two-Truck Shay "new" a few years ago and for various reasons never tested it until now (duh!); turns out the Motraxx motor is dead and of course now I can't return it. I've removed the body to gain direct access to the electrical terminals on the end of the motor housing/clip, so I'm certain the problem is not an electrical continuity issue somewhere between the wheels and the motor clip.

The model had a fair bit of oil on the frame directly under the motor; I suppose that oil inside the motor(?) could possibly be causing the issue, but the closed motor casing prevents me from knowing whether that's really the problem. Any suggestions what I can do to remove the oil from inside or flush it out(?). Can it be dropped into electrical contact cleaner?

If oil isn't the problem, then to eliminate the clip from the equation and test the motor directly means removing the brass flywheels and worm gears in order to remove the clip, but I'm not sure how to go about this since I don't see how the flywheel/worm gears are attached to the motor shaft. They appear to be a pressure fit since there's no access to the motor shaft at the end of the flywheel/worms (so a gear puller can't be used). Short of just yanking on the brass flywheels with pliers, I'm not sure what options I have; any thoughts or suggestions?

It looks like these Motraxx motors can still be purchased (though not from Atlas, so sans flywheel/worm gears) so if the motor actually turns out to be dead, I can likely replace it but I'd still need to have usable flywheels/worm gears to press on to the new motor.

Any advice/guidance/suggestions would be GREATLY appreciated.

[mmagliaro]

On the shay motors I have seen, you just pull the motor, clips and all, straight up out of the chassis.
And the worm end was hollow so that you can see the motor shaft in there, so you can use a gear puller to
take that whole flywheel/worm off.  But I have not seen the newer ones with the Motraxx motors.   Does it not have the
motor shaft exposed on the end?

Other questions:
-When you apply power directly to the exposed motor contacts at the clip, can you put an ammeter in line and see if it is
drawing current?   Also, rotate the motor shaft slowly with your hands while you are measuring and see if you see any
spikes of current at certain places in the rotation, followed by zero current at others.  That might indicate that the commutator
is clogged up with oil or brush material, and it might be worth a try taking the motor apart, removing the armature, and cleaning
everything.  If you are not up for that sort of surgery, then your only recourse will be replacing the motor.  If the shaft ends are
exposed, you can use a puller to get them off, hopefully.  But if not, since the old motor is toast anyway, what I usually do in those
cases is slip thin wedges of metal in between the flywheel and motor case and tap with hammer to force the flywheel off.  Often,
this will tear the shaft right out of the armature, but since you can't save the old motor anyway, no harm done.  You end up
with a worm/flywheel with a shaft sticking out of it, but that's easier to work on.  You can clamp the shaft firmly in a vise, and then use
metal wedges between the flywheel and vise to pop it off the shaft.

[u18b]

Early versions had clips at the bottom of the motor.   These damaged VERY easily.

Atlas wisely switched to screws to hold the motor.

However, the old worms were solid on the end if I remember.
This is tough to deal with.

The newer ones are hollow and thus easier to deal with when using a puller.

[randgust]

I have two of them.   I've never figured out a way to get the flyworms off without damaging something.   The worm is an odd / tight pitch, I suppose you could find a worm elsewhere if you knew what pitch that was you could put a different worm on a different motor.  Shay #2 is just a parts unit to keep Shay #1 running.  I already sold the body shell.

I want the trucks for another project, because they are the right wheelbase and diameter.   Overall wheelbase is too long, I want worms that will engage those spur gears but have no idea where to get them.   The motor/flyworm assembly is too long as-is, but I can't get them off, either.

I suspect only the flywheel is drilled, not the worm, with a shorter motor shaft on both ends.

If somebody can find me the right worms I'd probably even sell you the existing motor.....

[craigolio1]

I’ve done two Atlas Shay DCC installs and in both cases the tabs on the motor were attached to additional tabs that then had wires soldered to them. There the extra tabs attached to the motor tabs there was corrosion. I could this eventually getting so bad that it would interrupt the connection to the motor.

You can see it in one of my threads here.

https://www.therailwire.net/forum/index.php?topic=50415.0

I removed those tabs, cleaned the motor tabs and soldered wire directly to them.

Craig

[mmagliaro]

Okay, here's how you get the worm and flywheel off an Atlas Shay.  All you need is a lathe and two different gear pullers, and associated drill holding fixtures for the lathe.  Not joking.  It's easy if you have the tools, and probably agony if you don't.  The only slightly wonky
thing about this approach is holding the motor out in space while drilling, only clamped into the lathe by the opposite flywheel. 
But since this has a relatively low-precision requirement with soft brass, you can just run the drill slow and it works fine. You don't have
to apply much pressure while drilling, so the opposite flywheel doesn't slip on the shaft.

[peteski]

I have two of them.   I've never figured out a way to get the flyworms off without damaging something.   The worm is an odd / tight pitch, I suppose you could find a worm elsewhere if you knew what pitch that was you could put a different worm on a different motor. 

Yes, the worm seems to have pitch tighter than the typical Atlas/Kato worms.  If you determine the worm gear pitch then you will know what worm to get.

Remove the worm gear from the truck and measure the outside diameter of the gear. Also count its teeth.

The formula to determine the diametral pitch is DP=(N+2)/OD
N = number of teeth
OD = gear's outside diameter in inches

Due to the gear's diameter measurement not being perfectly accurate the DP might be slightly "off", but since gears usually follow standard set of pitches, it will be likely very close to a standard pitch. Now you can get the proper worm for a new motor.