(ET) RE: Motor problems

[Christopher Meier <Christopher Meier cwix com>]

Well, I took the end bell off the motor a few minutes ago,
and a pile of carbon poured out... :-(  I knew it wouldn't
be great news.  This is the first large DC motor I've ever
had apart...   The brushes protrude about 1/4 inch past the
holders when fully extended, so I'm guessing they are due
for replacement.  The commutator is pitted. The bearing on
this end makes some noise (clicking, sounds like a dry
bearing) as it spins, and it stops rather quickly.  Looks
like new bearings are in order.

Since it looks like I oughta disassemble and clean the
motor (should I?), how about some hints from the pros on
how best to proceed.  Just remove end bells, replace bearings
and brushes, and vacuum clean?  Or pull armature out?  Use
some type of electronic cleaner spray to clean up the armature,
brush holders, end bells, etc?  How about sanding the armature
before installing brushes, or would just no load running with
the new brushes for a while be sufficient?  Any suggestions
would be greatly appreciated.

Chris 

-----Original Message-----

Christopher and David have discussed a recalcitrant motor that
comes up with an occasional dead spot. 
If the brushes are down this far that one occasionally
will not touch, arcing will increase and the commutator will be
pitted - not good!

In smaller motors I have replaced brushes in incidents of the 
commutator having been pitted.  Running with no load for perhaps
a half hour cleaned up the commutator with no ill effects except
the loss of a bit of brush life.

Hope this helps.

                                        Rhett George