Atlas motor question - which side is up?

[Erik W]

I bought my first new loco in quite some time, an Atlas RS-3.  I tore it apart last night in preparation to installing the decoder.  I didn't pay attention to the orientation of the motor when I pulled it out.  Does anyone know which side is the top?  The motor is symmetrical in every way except on either the top or bottom of the metal housing around the armature, there is a small hole.  Is this side with the hole the top or bottom?  Or is it not consistent?  I'm trying to be somewhat lazy and not have to reassemble the mech and run it in order to figure out which is which.

Erik

[wm3798]

I run into the same problem all the time.  I've learned to use a Sharpie to mark the frame facing me when I open up the drive before I take anything else apart.  I also use a silver Sharpie to mark the bearings on the worm gear to make sure I put it back together the same way I take it apart.  Lacking that, there should be a white mark on the side of one of the magnets, too.  If I remember correctly, that goes on the side facing away from you when you're reassembling.

Worst case, put it back together and run it with another DC engine.  If they both run in the same direction, you win.  If not, then you know what you have to do!

Lee

[DKS]

...there should be a white mark on the side of one of the magnets, too.  If I remember correctly, that goes on the side facing away from you when you're reassembling.

Which side is supposed to be facing away from you? What happens if you flip things over?

[wm3798]

Okay...  You lay the frame on its side with the phillips screws facing you.  You unscrew them, and pull the top half off.  When you look at the motor, you should not see the white mark.  How's that?  This is really a one-way operation, because the bearings and worms can only be installed on one half of the frame.  unless you're operating in zero gravity, that half has to be on the bottom when you're reassembling...

Lee

[Erik W]

That little voice in my head, that I never listen to, is telling me to reassemble it and check it on the layout.  I think I'll listen for once . . .

Erik

[bigford]

i did this with a life like fa-1 / fa-2 and some how i flipped the motor.
and when everything made it back to the track it was not to funny
watching the to loco pull away from each other. i even turned the trucks
around. it took me about 3 day to figure the problem  :-[

[DKS]

Okay...  You lay the frame on its side with the phillips screws facing you.  You unscrew them, and pull the top half off.  When you look at the motor, you should not see the white mark.  How's that?  This is really a one-way operation, because the bearings and worms can only be installed on one half of the frame.  unless you're operating in zero gravity, that half has to be on the bottom when you're reassembling...

Got it, thanks. I guess my problem was that I often wound up reassembling them starting with either half of the frame, and flipping it as needed to install the screws at the end, so I never thought as either of the halves as the "top".

[mmyers]

Doesn't really matter which way is up for DCC. Test run the motor with DC. A nine volt battery works well for this.  Get the motor spinning so that it will move the mechanism forward. Whichever brush has the positive connected gets the orange decoder wire.  

[wm3798]

It only doesn't matter with DCC if you haven't wired the lights in yet.  If you've got it wrong, set CV 29 to an odd number (reverses normal direction of travel) and wire the yellow lead to the front headlight and white to the rear.

Damn.  I usually charge for that kind of information!

Lee