Electric motor bearings
 

I have a 1 hp baldor motor, tefc 1800rpm with grease fittings that has
given me good service but now has a bit of a shudder on shutdown and a
little vibration while running. I can budget a replacement but I
wonder what is involved in replacing the bearings. I am not adverse to
buying tools and learning new skills, can someone give me a few
pointers.
The motor operates a grinding wheel with the motor oriented so the fan
is on top and the arbor for the wheel is on the bottom.

Thanks-Tom

In article , Beecrofter says...

I have a 1 hp baldor motor, tefc 1800rpm with grease fittings that has
given me good service but now has a bit of a shudder on shutdown and a
little vibration while running. I can budget a replacement but I
wonder what is involved in replacing the bearings. I am not adverse to
buying tools and learning new skills, can someone give me a few
pointers.

Those are abec-1 bearings, typically. They are available
inexpensively from most supply companies. I suspect you will
have almost no trouble replacing them - you might punch-mark
the end bell housings on the motor to get them back in the
same orientation, don't ever press through the balls on new
bearings (OK to do if you are removing scrap bearing though,
with a puller) and if you want to keep using the grease
fittings then don't put in sealed bearings.

Jim


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please reply to:
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In article ,
(Beecrofter) wrote:

I have a 1 hp baldor motor, tefc 1800rpm with grease fittings that has
given me good service but now has a bit of a shudder on shutdown and a
little vibration while running. I can budget a replacement but I
wonder what is involved in replacing the bearings. I am not adverse to
buying tools and learning new skills, can someone give me a few
pointers.
The motor operates a grinding wheel with the motor oriented so the fan
is on top and the arbor for the wheel is on the bottom.

Thanks-Tom

I have a small motor with a bad bearing, and the motor is irreplaceable.
Multi-speed, small size, exact fit reqd, part of a pair. Bearing is
loose and noisy, it's a fan on my wood stove and I cannot get to it when
the stove is hot.

My solution to date: I installed a tiny (ref capillary)tube to feed
thick oil (STP) to the bad bearing. Just a drop works wonders. The oil
would be too thick for good bearings but loose ones need thicker oil.
I'm using a 25ACP case for an oil reservoir, filled with cotton. Has
been working well so far. Note this is a horizontal shaft model, YMMV
with a vertical shaft.

--
Free men own guns, slaves don't
www.geocities.com/CapitolHill/5357/

New bearings should be easy. Mark the bells. I'd use sealed bearings. Why
did they fail? Even after a long time. Keep your wheels balanced and
dressed. Check your flanges.


"Beecrofter" wrote in message
om...
I have a 1 hp baldor motor, tefc 1800rpm with grease fittings that has
given me good service but now has a bit of a shudder on shutdown and a
little vibration while running. I can budget a replacement but I
wonder what is involved in replacing the bearings. I am not adverse to
buying tools and learning new skills, can someone give me a few
pointers.
The motor operates a grinding wheel with the motor oriented so the fan
is on top and the arbor for the wheel is on the bottom.

Thanks-Tom

"Tom Gardner" wrote in message
...
New bearings should be easy. Mark the bells. I'd use sealed bearings.
Why
did they fail? Even after a long time. Keep your wheels balanced and
dressed. Check your flanges.


"Beecrofter" wrote in message
om...
I have a 1 hp baldor motor, tefc 1800rpm with grease fittings that has
given me good service but now has a bit of a shudder on shutdown and a
little vibration while running. I can budget a replacement but I
wonder what is involved in replacing the bearings. I am not adverse to
buying tools and learning new skills, can someone give me a few
pointers.
The motor operates a grinding wheel with the motor oriented so the fan
is on top and the arbor for the wheel is on the bottom.

Thanks-Tom



All good advice, but while I was in there, I'd fold over a piece of 280
sandpaper and do a good job of cleaning the contacts on the centrifugal
switch if it's a cap. start motor. Blow everything out too.

Garrett Fulton




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"Tom Gardner" wrote in message m...
New bearings should be easy. Mark the bells. I'd use sealed bearings. Why
did they fail? Even after a long time. Keep your wheels balanced and
dressed. Check your flanges.


Well it's been in service here since 1987 so I'd imagine they are
failing from normal wear. I have just rebuilt the machine ways with
new linear shafting and bearings. No flanges per se as it uses plate
mounted wheels. The bit of vibration is requiring more wheel dressing
on some very friable open wheels.
The machine grinds the knives from wood chippers and the like.

Can sealed bearings fit where the ones with grease fittings were?

Beecrofter asks: "Can sealed bearings fit where the ones with grease
fittings were?"

Take this up with the friendly guy behind the counter of the local bearing
supply store. Bearing vendors are probably the most knowledable of their
trade among all the counter sales types. I am impressed every time I deal
with one.

Bob Swinney

Beecrofter" wrote in message
om...
"Tom Gardner" wrote in message
m...
New bearings should be easy. Mark the bells. I'd use sealed bearings.
Why
did they fail? Even after a long time. Keep your wheels balanced and
dressed. Check your flanges.


Well it's been in service here since 1987 so I'd imagine they are
failing from normal wear. I have just rebuilt the machine ways with
new linear shafting and bearings. No flanges per se as it uses plate
mounted wheels. The bit of vibration is requiring more wheel dressing
on some very friable open wheels.
The machine grinds the knives from wood chippers and the like.

Well it's been in service here since 1987 so I'd imagine they are
failing from normal wear. I have just rebuilt the machine ways with
new linear shafting and bearings. No flanges per se as it uses plate
mounted wheels. The bit of vibration is requiring more wheel dressing
on some very friable open wheels.
The machine grinds the knives from wood chippers and the like.

Can sealed bearings fit where the ones with grease fittings were?

Dimensions are the same for open, sealed and shielded bearings. I
would suggest shielded bearings unless you have a pretty severe
contamination issue. Shielded are cheaper than sealed, more readily
available and do a pretty good job of sealing out dust, dirt etc but
does not work for water. Contact seals create drag and limits your
speed (but probably is not a problem on 1800 rpm motor of this size).
If you need a better seal than the shields provide NTN makes a non
contact seal (add LLB to the basic bearing number) which provides
better sealing than the shield but still does not contact the raceway.
I'd also look for bearings lubricated with Exxon PolyRex EM grease -
pretty much the new standard for electric motor manufacturers. Be sure
to press the new bearings on the shaft using the inner race if you
don't have a bearing heater to prevent brinnelling and shortening the
life. Good luck - let us know if you have any further questions.

"Tom" wrote in message
.. .

Well it's been in service here since 1987 so I'd imagine they are
failing from normal wear. I have just rebuilt the machine ways with
new linear shafting and bearings. No flanges per se as it uses plate
mounted wheels. The bit of vibration is requiring more wheel dressing
on some very friable open wheels.
The machine grinds the knives from wood chippers and the like.

Can sealed bearings fit where the ones with grease fittings were?

Dimensions are the same for open, sealed and shielded bearings. I
would suggest shielded bearings unless you have a pretty severe
contamination issue. Shielded are cheaper than sealed, more readily
available and do a pretty good job of sealing out dust, dirt etc but
does not work for water. Contact seals create drag and limits your
speed (but probably is not a problem on 1800 rpm motor of this size).
If you need a better seal than the shields provide NTN makes a non
contact seal (add LLB to the basic bearing number) which provides
better sealing than the shield but still does not contact the raceway.
I'd also look for bearings lubricated with Exxon PolyRex EM grease -
pretty much the new standard for electric motor manufacturers. Be sure
to press the new bearings on the shaft using the inner race if you
don't have a bearing heater to prevent brinnelling and shortening the
life. Good luck - let us know if you have any further questions.

Iset my bearings on a 100w light bulb for a little while to expand them a
little and warm the grease.

Iset my bearings on a 100w light bulb for a little while to expand them a
little and warm the grease.

Why do you want to warm the grease??

"Beecrofter" wrote in message
om...

Can sealed bearings fit where the ones with grease fittings were?

If you do replace the open cage bearings with shielded or sealed, be
sure to remove the grease fitting and plug the hole. It will not help
any when someone 3 - 4 years down the road tries to lube the bearing
and the grease has nowhere to go.

Nate


--
http://www.Weber-Automation.net:8000

In article ,
says...

Well it's been in service here since 1987 so I'd imagine they are
failing from normal wear. I have just rebuilt the machine ways with
new linear shafting and bearings. No flanges per se as it uses plate
mounted wheels. The bit of vibration is requiring more wheel dressing
on some very friable open wheels.
The machine grinds the knives from wood chippers and the like.

Can sealed bearings fit where the ones with grease fittings were?

Dimensions are the same for open, sealed and shielded bearings. I
would suggest shielded bearings unless you have a pretty severe
contamination issue. Shielded are cheaper than sealed, more readily
available and do a pretty good job of sealing out dust, dirt etc but
does not work for water. Contact seals create drag and limits your
speed (but probably is not a problem on 1800 rpm motor of this size).
If you need a better seal than the shields provide NTN makes a non
contact seal (add LLB to the basic bearing number) which provides
better sealing than the shield but still does not contact the raceway.
I'd also look for bearings lubricated with Exxon PolyRex EM grease -
pretty much the new standard for electric motor manufacturers. Be sure
to press the new bearings on the shaft using the inner race if you
don't have a bearing heater to prevent brinnelling and shortening the
life. Good luck - let us know if you have any further questions.


Some shielded/sealed bearings are wider than the unsealed
bearing, not many and usually in smaller or thin section
bearings, but it's worth being aware. Also, the runout
allowance and some of the dimensional tolerances are
greater on shielded and sealed bearings than the unsealed
version. I mention this since it sounds as though these
bearings double as a grinding spindle.

Ned Simmons

Why do you want to warm the grease??

Not necessary, I'm sure, but it redistributes the grease and makes sure it
hasn't seperated. The first few minutes in a bearing's life are crutial.

On Tue, 31 Aug 2004 13:37:35 GMT, "Tom Gardner"
wrote:

Why do you want to warm the grease??

Not necessary, I'm sure, but it redistributes the grease and makes sure it
hasn't seperated. The first few minutes in a bearing's life are crutial.

I don't think you're accomplishing anything. You should never heat a
bearing over 148 degrees C. to install (don't think you can get there
with a light bulb) and the grease shouldn't flow until you reach
approx. 170 (varies depending on grease). The grease is instantly
redistributed as soon as the bearing rotates.

I'm old now and don't respond well to logic. This is the way I do it! I
always face the bearing North when light bulb heating to make sure it
alligns with North magnetic pole, allowing for deviation and compensation.


"Tom" wrote in message
. ..
On Tue, 31 Aug 2004 13:37:35 GMT, "Tom Gardner"
wrote:

Why do you want to warm the grease??

Not necessary, I'm sure, but it redistributes the grease and makes sure it
hasn't seperated. The first few minutes in a bearing's life are crutial.

I don't think you're accomplishing anything. You should never heat a
bearing over 148 degrees C. to install (don't think you can get there
with a light bulb) and the grease shouldn't flow until you reach
approx. 170 (varies depending on grease). The grease is instantly
redistributed as soon as the bearing rotates.

On Tue, 31 Aug 2004 15:51:10 GMT, "Tom Gardner"
wrote:

I'm old now and don't respond well to logic. This is the way I do it! I
always face the bearing North when light bulb heating to make sure it
alligns with North magnetic pole, allowing for deviation and compensation.

Now that makes sense! Gotta allow for the compensated deviates in this
world!
Gerry :-)}
London, Canada

OK so this is what I have learned so far.

Electric motor bearings have so little load they should last a few
lifetimes.

The original bearings probably fail because coolant either gets past
the shaft or as the unit heats up and cools down vapor condenses
inside and this causes lubrication failure or corrosion. Not too bad
for 17 years of hard use.

Bring the old bearing with me to the distributer in case there are
size differences.
Don't push against anything but the inner ring.
Use a lamp to preheat the bearing and try to get the newer lube.


Because the coolant kind of mists around I expect the next set to fail
around 2021.

Now if I go with bearings that need grease through the zerk fittings
whats a good policy for maintaining them, I know overlube kills more
things than underlube cause I've done it on other things.

On Tue, 31 Aug 2004 15:51:10 GMT, "Tom Gardner"
wrote:

I'm old now and don't respond well to logic. This is the way I do it! I
always face the bearing North when light bulb heating to make sure it
alligns with North magnetic pole, allowing for deviation and compensation.

But don't forget to spin it on the bulb after heating to de-magnatize
it - otherwise you may attract contaminates and they'll be sucked in
as it cools. :-)

Now if I go with bearings that need grease through the zerk fittings
whats a good policy for maintaining them, I know overlube kills more
things than underlube cause I've done it on other things.

You're exactly right about overlube. Exxon/Mobil has done some
research and has actually measured the amount of grease dispensed by
individual grease guns and determined lube schedules based on that. It
only amounts to a shot or two every 6 months or so (depending on
application. I'll try to find the info for you. Another strange
thought is to use a single shield bearing and mount it with the shield
toward the lube source - actually acts as a metering device to help
prevent overlube.

On 1 Sep 2004 05:52:40 -0700, (Beecrofter) wrote:

snip

Don't push against anything but the inner ring.

Push on the inner race if pressing onto the shaft.
Push on the outer race if pressing into the housing.

i.e. Don't squash the bearing's balls. You know what it feels like, so have
pity on the poor bearing :-)


Mark Rand
RTFM

I have the motor disassembled and now I can see why they claim
electric motor bearings should last lifetimes barring lubrication
failure, arcing , or contamination, these things are massive.
It looks like dried flakes of coolant or perhaps the corrosion the
coolant did to the metal ends of the motor was the culprit, the grease
itself was there without being excessive. The motor shaft end bearing
has a bad feel and a little looseness and I believe it was just enough
to cause the cup wheel to pound in a few spots and glaze up. I think
when I put the thing back together I will make some sort of "flinger"
from coffee can lid plastic just far enough from the motor housing to
not rub. Although I can't complain about the service this thing has
given me.

Thanks again for all the help.
Tom