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Re: (ET) Elec-trak Digest, Vol 4, Issue 370
Chip,
Do a good thorough blow out and clean-up.
- No liquid solvents on the windings!
- Pull some sandpaper (non-metallic preferred) around the commutator to
smooth it up.
- Buff up brush faces
- Clean slots between commutator bars and blow out carbon - make sure mica
doesn't stick up.
- Check all internal connsctions and fix + lead.
- New bearings wouldn't hurt while it's apart.
Good Luck....
Walt K
GE Motors Erie PA
-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu]On Behalf Of Chip Gribben
Sent: Monday, October 16, 2006 4:27 PM
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) Elec-trak Digest, Vol 4, Issue 370
Thanks Dave,
I pulled the motor and took it apart.
Half the comm (180 degrees) is blackened where the brushes contact
the comm. And its interesting because it is exactly half of it. There
is a slight depression in the comm where the black starts where it
looks like something was stuck between the brush and the comm.
The brushes look good and the bearings are spinning fine. The
armature looks good. Nothing scored that I could tell, but it needs a
good cleaning. There isn't that acrid smell I sometimes smell when a
motor burns up which is good news.The inside is awfully filthy with
lots of carbon dust all over. I'm going to wear a mask when I clean
it up. The stud where the positive cable connects to is really loose
though. It doesn't look like it was making a good connection because
the whole stud was spinning while I was trying to take the positive
lead off.
I'm going to clean it up and fine file the comm where it is black and
put it back together and bench test it. I don't have a comm stone and
not sure where to get one.
I haven't had a chance yet to test out the charger and see what is up
with that.
The next problem is the darn rear tire keeps going flat. I was hoping
it was just a slow leak from the tractor sitting for the past year
but it's taking about a week for it to go flat. I'm not sure how to
take wheel off this thing.
Thanks for the advice.
Chip
On Oct 16, 2006, at 12:00 PM, elec-trak-request cosmos phy tufts edu
wrote:
> Message: 2
> Date: Sun, 15 Oct 2006 20:58:17 -0400
> From: David C Robie <mycroftxx1 juno com>
> Subject: Re: (ET) Arcing motor
> To: futurev radix net,elec-trak cosmos phy tufts edu
> Message-ID: <20061015 213521 -291531 1 mycroftxx1 juno com>
> Content-Type: text/plain
>
>
> Hi Chip
>
> Charger; if it's still there and works, you can take out the GE
> countdown timer, and put in an air conditioner type timer (the
> plastic
> 24 hour type you get cheap in hardware stores. The only problem
> is that
> it repeats the time set in every 24 hrs. To stop this and make it
> a 'one
> shot' timer, get inside of it and break off the plastic 'pin ' that
> turns it on - that way you turn it on then it turns itself off
> according
> to the time you set and don't repeat. I did this yrs ago to one
> tractor
> and it's still in there working when I need it (which isn't often
> as most
> Etractor charging here is solar photovoltaic)
>
> As to motor: Take her apart and see if there is a short caused by
> a dig
> either between 2 ajacent commutator bars, or at the exposed armature
> wires next to the commutator or on the other side of the armature.
> This
> is often caused by foriegn material (China? Taiwan? or some little USA
> thingus that fell into the aircooling vent years ago) - or could be a
> little broken off piece of the field magnet scoring the commutator so
> deep that it becomes a short, or hittin the armature winding and
> shorting
> wires together..
> Another thing that is known to happen (especially in 12 motors) is
> that
> the centrifugal 'rpm limit' switch comes apart with pieces making a
> short there - or if getting between armature and magnet, locking the
> motor up tight. You can do without this rpm limiter (if you have one)
> as it's limited by the mechanical resistance of the belt and tranny
> gears
> even in neutral. I took all gov parts out of my 12 clone (WH 145)
> rather
> than put it all together and have to pull it apart sometime in the
> future
> for the same thing, or hunt for a new assy. Motor, because of this
> mechanical resistance, does not overspeed.
> If you find a short and fix it, clean up the commutator and
> brushes,
> make sure brushes are not sticky in their holders. I usually stone the
> brushholder insides if there is any hint of brush binding. This
> binding
> could be your 'motor stop' or it could be the circuit breaker
> feeling a
> partial short and heavy draw in the motor.
> Don't worry about a dig in a commutator bar. Fine file the
> copper so
> it's slick where the brush runs across it nothing protruding no sharp
> edges. Make sure the whole bar hasn't lifted up high, if it has,
> with a
> hammer and block of wood tap it back even with the others.
> Done a couple of these (but in an 8 and 12) they are not a big
> job
> except for getting the motors out to work on. But did a lot of em yrs
> ago on prewar vehicle generators, bout the same breed of cat but
> have a
> wound field.
>
> RSVP to this after you get her apart, let us know what happened in
> there.
> Armature shorts, unless externally caused and plainly visible as
> above,
> are very rare.
>
> Dave
> Weymouth MA
> (NE Chap EAA Sec)
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