Atlas/Tomix vacuum car problems

[peteski]

I don't have mine handy but IIRC, there are no metal  tabs there. All plastic. These brush holders (like in many small motors) are simply press fit into the plastic. Often there is a barb around the brass piece to lock them in place in the plastic brush housing.  You simply need to pry or pull the holder out. I use pair of fine wire cutters to grab the holder at the base and use them as a lever to pry it up. 

Without take the brush holders and brush/spring out you will not be able to reassemble the motor (for the reason you mentioned).

Is for the grit, since this  is a rail  cleaning car with a vacuum, I'm not too surprised that there was some grit inside the motor.  That stuff gets everywhere.

[Maletrain]

Peteski seems to be right about the brush holders being press-in types.  With a 15x loupe I can see a shallow barb on the inside.  It is beveled to go in easily, but has a squared face on the side that has to enter the hole to come out.  So that looks like a one-time operation.  Unless I really want to bugger the hole.  If I bugger the hole, will the brush holders be able to maintain their position when I reinstall them later?  Would I need to glue them?

Max may be onto something with those tiny black tabs, but I can't figure out what.  They look like they are to be used to somehow move a black square of plastic with the brush holder in it.  I wondered if they could be split rings, but it doesn't look like that in the loupe view.  It looks like the black plastic squares should move outward, based on where the seams appear to be in the black plastic case.  But, I have not been able to move anything with those black tabs when using as much force as I (currently?) dare, for fear of just breaking them off.

I was originally thinking that this motor was already toast, because it was in the vacuum car that had all sorts of corrosion all over it.  So, I was taking it apart as a leaning experience to be able to better deal with the other 2 vacuum car motors.  So, losing this motor isn't really the issue.  The issue is really that I still seem to have something here to learn.

[peteski]

You guys seem to be overthinking it.  The black tabs do not appear to have anything to do with the brush holders. I seem to recall they were used in a similar motor as the retainers for the motor.
Yes, the brush holders are designed for one-time install, but if carefully reinstalled, they will still be tight enough to stay in place, have installed/removed them multiple times on another similar motor and they remained in place. The black plastic has enough flexibility to retain them.

[Maletrain]

From the outside, those tabs do look like they connect to a rectangular panel with the brush housing penetrating it. 

But, after pulling/pushing on them every which way, and nothing was moving, I started bending the tabs.

So, I used Peteski's wire cutters for leverage method and removed both brush holders. 

With the brush holders out, I still could not see any parting lines for those rectangles on the inside surfaces.  And, I am not seeing any way they are used in assembling the motor into the vacuum car. 

So, the tabs just remain a mystery.

Now, to reassemble and see how it holds up to running.

I am thinking I need to lube the bearings.  Oil or dry lube?

[peteski]

Those tabs are molded along with the entire plastic end of the motor. It is all one piece of plastic.  I did not say that those tabs were used in this model. I just mentioned that I seem to recall that similar tabs were used in another model to either retain or keep the motor aligned.  This motor and similar motors are used in many different models.

Steve, motor (and worm shaft bearings in different models) should be lubricated with light oil. Just like in any other N scale mechanism. The bearings are usually made from sintered bronze which absorb the oil for a long time lubrication. You seem to be an experienced modeler. Have you ever encountered motors lubricated with dry lubricant?  Just do not over-oil the bearings, especially on the commutator end, so the oil does not ooze out onto the commutator.

[Maletrain]

Peteski,

I have never seen dry lube used alone in HO or N scale models (unless you count NeoLube or Microtrains' "Gease-em" graphite powder for couplers).  I have used some (PTFE, Molybdenum Disulfide, powdered graphite, etc.) in other, macro type applications, which is why I asked.  I note that Labelle sells oils with PTFE for HO and N scale model trains.

These bearings see relatively high speed shafts for extended periods when used to power the vacuum function.  Remember when I started this thread that I was seeing one of the other cars draw high current and seize up at relatively low DC voltage after I unstuck its shaft.  And, that now seems likely to have been due to the same shaft bearing that was the problem with this car.  Those are both the Atlas version of the vacuum car, which has that bearing sticking through the top of the car housing.  Maybe that was so that it could be oiled frequently, but I did not see anything about oiling it in any instructions.  It also makes that bearing more exposed to layout gunk, which might be the reason that those 2 cars had stuck motor shafts.

The (new/unused) Tomix version of the vacuum car that I plan to convert to DCC does not have the upper motor bearing exposed outside of the car.  So, that makes it less convenient to oil, but also makes it better protected from gunk.  At least I hope so - I wonder if the vacuum might push dust back into that compartment. 

But, I still want to lube it periodically.  Just not sure what the period should be between lube applications if that lube is light oil.  I am guessing Labelle #108.  That comes with "PTFE" which is a dry lube powder version of Teflon.  Or maybe #107, which comes with or without PTFE?

So, again, I'll ask the much more experienced folks here on TRW.  What lubricant do you and Max use for these bearings?  And, how often do you apply it?

[peteski]

You asked if "dry lube" should be used to lubricate the motor. Labelle #108 is an oil with PTFE added (in the oil suspension).  That is different than a dry lubricant (like dry PTFE powder ) which was what I thought when you mentioned "dry lubricant".  I use Woodland Scenics hobby lubricants but the oil you have and uses will be fine for motor bearings. So if you ask if Labelle #108 is good for this application, I will say yes.  Also both bearings will need to be lubed. The bottom bearing will be a bit more difficult to get to.

As for why liquid lubricant is needed for motor bearings, it is because at high speeds the motor shaft actually floats on a cushion of liquid lubricant. That is why dry motor and worm bearings make a loud screeching noise. Dry lubricant (if you could even somehow apply it to the bearings) would not work well. At least that is in my model train experience.