|
Hey Group
I have a few things to add. I will have to
disagree with Steve on one thing. I have been told many times by factory tech
services at Yale Forklift not to use sandpaper of any type on the commutators.
They tell us to have them turned or use a Commutator Stone. They say that the
sand will embed in the commutator and damage commutator and
brushes.
Also before you disassemble the case put
permanent marks on the case and ends with a punch so that all parts are put back
in the same location. This will save a lot of time when you reassemble the
motor.
,,,,,
( o o )
,
--------oO0---(_)---0Oo-------------,
| Tony "forky bellsouth net
|
`--------oOO0--------0OOo-----------'
( )\---/( )
\_| |_/
----- Original Message -----
Sent: Monday, January 11, 1999 8:54 PM
Subject: (ET) Chris's motor and rebuild advice
Chris,
Larry Elie is right, do be careful
when repairing your motors. However
I've rebuilt 10 motors so far
without any problem. They were:
1. 6 small mower deck motors
(permag). 3 needed just bearings, 3 needed
brushes too.
2. 2
E15 traction motors (shunt field). 2 needed just bearings, 1
needed
brushes too.
(The brush failures were due to water getting in the
motors and corroding
the copper wire to the brushes.)
3. 1 snow
blower motor (shunt or series field, I don't remember which).
Needed just
bearings.
4. 1 leaf/grass vacuum blower (permag). Needed just
bearings.
I've learned that the GE motors are
overbuilt. None of the motors had
any significant commutator
wear. The brushes would have all had more than
50% life if it weren't
for the motors that had the water problem. Even
then, they were
otherwise undamaged.
Here are some rules I now use
when rebuilding the GE motors.
Professional motor shop people most likely
will have somewhat different
recommendations, but these worked for
me.
0. Most important. Make a sketch of how the motors come
apart. Shims and
washers need to be in the right place.
1.
Use only emery cloth to polish the commutators. In one case I
used
green Scotchbrite followed by emery cloth. Green Scotchbrite
alone is too
aggressive.
2. Use only compressed air to clean the
rotors.
3. You can bead blast the cases if you want to
repaint. Sandblasting
could be used if you are very careful. Do
not blast the inside of a case
with a wound field. Be extra careful
about removing all blast media from a
field winding. In many cases it
might be best to not blast a case with a
wound field, but I have gotten
away with it so far.
4. Replace brushes if they don't have at least
1/2 their length still in
the brush holder. I usually replace them
even if they have 70% life left
because replacing brushes is relatively
cheap.
5. Be careful of a permag motor case. Also, removing or
replacing a rotor
in a permag case is tricky because no matter what, the
magnets seem to fight
you. You can dent or damage the insulation of
some of the rotor wiring. If
you break a big magnet chip off, you
should replace the case because you
have permanently weakened the field
strength. If you break a small chip
off, the case is usually still
good to use, but if you lose the chip in the
motor it can jam the motor
later and cause much more major damage.
6. Use 320 grit or finer (400
is safer) if you need to remove corrosion
from the rotor shaft or in the
end caps where the bearings fit. Remove all
abrasive dust when
through.
7. Replace all shielded bearings with dual seal bearings,
even if they seem
good. Sealed bearings retain grease better.
If you have a motor apart,
replace at least the motor shaft end
bearing. That one has the highest
loads. I've always replaced
both bearings.
8. Use a hydraulic press and split bearing pullers to
remove all old
bearings. Other tools can damage the
shaft.
9. When pressing on a new bearing, only push on the inner
race, and try to
use a hydraulic press. Pushing on the outer race
will cause you to dent the
races greatly reducing their lifetimes.
Hammering a bearing, even on the
inner race, can sometimes also dent the
races.
10. If for some reason you start to install a bearing and then
have to
remove it, be warned. Unless you remove by only putting force
on the inner
race, you have a large chance of damaging an otherwise new
bearing. If you
are not sure, discard the now questionable new
bearing and get another. You
don't want to do another rebuild after
only one year.
11. Use your sketch (see step 0) to reassemble things
in the right order.
I use a light grease film in the case ends where the
bearing go. Use too
much and it can migrate to places you don't want
grease.
12. Test your motor, preferably before reassembly into the
tractor or
accessory. Careful, it will want to spin away from you if
not clamped to
something. (I know.)
I have been
told that you should test the armature with a growler, but I
don't have
one. (If I find a good deal at an auction I'll buy it.) What
I
have found in my limited experience is that is the motor worked before
it
came apart, it will work proper after proper reassembly. If you
don't have
all the electrical test equipment AND the motor didn't work
before
disassembly, it may be worth having a motor shop check it out before
doing
much work to it. You be the judge of whether it costs more just
install the
new bearings and brushes or slipping the motor shop guy some
beer money.
Chris, hope this helps you.
Steve
Naugler
|