I have to replace some bearings in a generator I have. I discovered they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the same? I want to replace these bearings with the best I can get.
Thanks for any pointers.

On Tue, 2 Jan 2007 18:47:21 -0000, tg wrote:

I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can
get. Thanks for any pointers.



yes, they do come in different grades and qualities. Can you ask the
manufacturer for what they recommend?

i

"Ignoramus13628" wrote in message ...
On Tue, 2 Jan 2007 18:47:21 -0000, tg wrote:

I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can
get. Thanks for any pointers.



yes, they do come in different grades and qualities. Can you ask the
manufacturer for what they recommend?

I don't trust those girls that answer the phone at the manufacturers. I'd rather just go for the best I can get - if I can get
advice about what's available. If I ask a local supplier they will only tell me what they've got, rather than what are the best
type.

On Tue, 2 Jan 2007 18:58:16 -0000, tg wrote:

"Ignoramus13628" wrote in message ...
On Tue, 2 Jan 2007 18:47:21 -0000, tg wrote:

I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can
get. Thanks for any pointers.



yes, they do come in different grades and qualities. Can you ask the
manufacturer for what they recommend?


I don't trust those girls that answer the phone at the
manufacturers. I'd rather just go for the best I can get - if I can
get advice about what's available. If I ask a local supplier they
will only tell me what they've got, rather than what are the best
type.

I found that customer service reps at manufacturers that I call for
suggestions, are actuially either helpful or can take me to competent
engineers.

i

"tg" wrote in message
...

"Ignoramus13628" wrote in message
...
On Tue, 2 Jan 2007 18:47:21 -0000, tg wrote:

I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can
get. Thanks for any pointers.

yes, they do come in different grades and qualities. Can you ask the
manufacturer for what they recommend?

I don't trust those girls that answer the phone at the manufacturers. I'd
rather just go for the best I can get - if I can get advice about what's
available. If I ask a local supplier they will only tell me what they've
got, rather than what are the best type.

Define "best". Longest lasting? Smoothest running? For some applications,
the cheapest are the best choice because that's all they need.

Also, assuming you've decided you want eg the longest lasting ones, how far
up the price/performance curve are you actually prepared to go? If the
normal ones are a fiver, are you prepared to pay 100 quid for ones which may
last twice as long?

(and a side question : I know ball bearings come in different qualities - do
the sealed ones have the same range, or are they rather more standardised?)

cheers,
clive

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "tg"
saying something like:

I have to replace some bearings in a generator I have. I discovered they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities?

They certainly do.

Or are they all the same? I want to replace these bearings with the best I can get.
Thanks for any pointers.

Avoid RHP for a start. SKF are good, but Toyo are the best.

I can tell you from some time I spent directly involved in making the
things that Toyo were the most exacting specs.
--

Dave

"Clive George" wrote in message ...
"tg" wrote in message ...

Define "best". Longest lasting?

yeah, longest lasting

In message , tg
writes
I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can get.
Thanks for any pointers.

Umm... in essence yes. Or rather you get what you pay for:-)

It is 25 years since I had a proper job; working for SKF at Luton so a
certain amount of rust may have affected my knowledge.

Different manufacturers use different steels and hardening methods which
confer different characteristics to the life and robustness of the
product. Also the fit between the balls and the grooves has a big impact
on the noise and performance. Quiet bearings have a shorter life.

I would avoid Japanese; Asahi for instance.

SKF used a through hardening steel whereas RHP used a case hardening
process.

There is a massive mark up on bearings. Employees were entitled to 60%
discount on deep groove and 40% on tapers.

Care is needed when fitting replacements as simply whacking them in with
a steel hammer is likely to cause damage.

Others may care to advise.

regards





--
Tim Lamb

"tg" wrote in message
...
I have to replace some bearings in a generator I have. I discovered they
are a common size - 6302-2RSH. What I want to know is, do bearings come in
different grades or qualities? Or are they all the same? I want to replace
these bearings with the best I can get. Thanks for any pointers.
I believe that bearings from a _reliable source_ are generally of good
similar quality.
Your question reminds me of some interesting info (if memory allows). A
certain British army tank had to rely on a source of Russian bearings, as
they were not available anywhere else, at short notice.
I think that the "cold war" was still on.

Sylvain.

"tg" wrote in message
...

"Ignoramus13628" wrote in message
...
On Tue, 2 Jan 2007 18:47:21 -0000, tg wrote:

I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can
get. Thanks for any pointers.



yes, they do come in different grades and qualities. Can you ask the
manufacturer for what they recommend?

I don't trust those girls that answer the phone at the manufacturers. I'd
rather just go for the best I can get - if I can get
advice about what's available. If I ask a local supplier they will only
tell me what they've got, rather than what are the best type.

I think that you're worrying unnecessarely about quality. I do know that
"Timken" make (or did make) good tapered roller bearings.
You're talking about ball bearings, I assume.
You can also get parallel roller bearings, tapered roller bearings, needle
roller bearings, thrust-type ball bearings, etc..
The ordinary (journal) ball bearings can have different clearances (they're
marked with a number of zeros on their circumference). If they are a loose
fit, they will have a small clearance (between the balls and the inner and
outer tracks). and if they are a tight interference fit, they will have a
greater clearance to allow for this.

Sylvain.

tg wrote:

I have to replace some bearings in a generator I have. I discovered they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the same? I want to replace these bearings with the best I can get.
Thanks for any pointers.

As to grades you should fit a matching grade to what you are replacing
- or ask manufacturer for the grade.

Just throwing money at it is not the right thing to do ... you want the
bearing to match the parts it is designed to work with ... what is
point in putting in something 10 x the price it needs to be.

As another poster said Toyo bearings are good ... I used INA bearings
on most jobs
www.ina.co.uk/

Although I usually go to local Bearing Supplies drop the old ones on
the counter and ask for replacements - simple as that.

"Grimly Curmudgeon" wrote in message ...
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "tg"
saying something like:

Avoid RHP for a start. SKF are good, but Toyo are the best.

thanks for this feedback, it's good to have a name to go on.

Blind posted because top and bottom are boring...

Higher bearing grades generally mean higher RPM with less heat generated.
It usually has to do with the surface quality of the balls or rollers in the
bearings... And of course the "race" that they run in.

Match the RPM of your machine to the rating of the bearing and you should be
fine. Use a higher rated bearing if you wish for longer life. Going much
beyond a single grade above is probably a waste of $$$. ...You could
actually go to ceramic bearings if you want to simply give money way though.


Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com

V8013-R

In message , Clive
George writes

Define "best". Longest lasting? Smoothest running? For some
applications, the cheapest are the best choice because that's all they
need.

Also, assuming you've decided you want eg the longest lasting ones, how
far up the price/performance curve are you actually prepared to go? If
the normal ones are a fiver, are you prepared to pay 100 quid for ones
which may last twice as long?

(and a side question : I know ball bearings come in different qualities
- do the sealed ones have the same range, or are they rather more
standardised?)

Bearings are sealed depending on their application and intended
lubrication. eg. an electric motor bearing might have the dirty
*windings side* sealed and the clean side open for grease lubrication.

Internal construction has not cropped up yet and my bearing book is over
in the workshop, steel cages, brass cages, nylon/plastic, fully filled
etc. etc. AFAIR the numbers give the o/d, i/d, width and abutments and
the letters refer to the cage and sideplates.

regards

--
Tim Lamb

"Tim Lamb" wrote in message
...
In message , tg
writes



snip)

Care is needed when fitting replacements as simply whacking them in with a
steel hammer is likely to cause damage.

Others may care to advise.

Use a copper or brass drift (punch) the same size as the bearing track (a
tube would be best, but you would need a lot of them). If the outer track is
an interference fit, tap on that. If the inner track is an interference fit,
then tap on that one. If both tracks are an interference fit (Ford Transit
rear hub bearings, for instance), use a drift wide enough to cover both
tracks, taking care not to damage the balls' cage.
Of course, if you have a hydraulic press with suitable fittings, so much the
better (only to put the bearings in their housing, I suppose).
I nearly forgot: Aluminium casings should preferably be expanded with the
use of heat, before fitting any bearing.

Sylvain.

regards





--
Tim Lamb

I would avoid Japanese; Asahi for instance.

True in the 70's, not now. Maybe avoid Chinese low-end manufacturers??

SKF used a through hardening steel whereas RHP used a case hardening
process.

Certainly not in small sizes! Anyway RHP are now owned by NSK.

When I was doing basic research on rolling element bearings in the 70's and
80's the general consensus was that there was little to choose between the
big names (SKF, NSK/RHP, and FAG). Timken specialise in big case-hardened
taper rollers typically used in the "tough" end of the market.

There is a massive mark up on bearings. Employees were entitled to 60%
discount on deep groove and 40% on tapers.

Care is needed when fitting replacements as simply whacking them in with a
steel hammer is likely to cause damage.

Agreed on both counts

Your question reminds me of some interesting info (if memory allows). A
certain British army tank had to rely on a source of Russian bearings, as
they were not available anywhere else, at short notice.
I think that the "cold war" was still on.

I'd not heard that one (sounds a bit Urban Myth to be honest, as Wyko could
make anything at a price, but maybe it was to do with delivery), but when I
was trying to source asbestos clutch linings to keep an old UK nuclear power
station going I was interested to find that you could still fit asbestos to
Challenger tanks

On Tue, 2 Jan 2007 20:01:12 +0000, Tim Lamb
wrote:

In message , tg
writes
I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can get.
Thanks for any pointers.

Umm... in essence yes. Or rather you get what you pay for:-)

It is 25 years since I had a proper job; working for SKF at Luton so a
certain amount of rust may have affected my knowledge.

Different manufacturers use different steels and hardening methods

All ball bearings are made from SAE 52100 steel.
Check with the ABMA or ISO and see.

which
confer different characteristics to the life and robustness of the
product. Also the fit between the balls and the grooves has a big impact
on the noise and performance. Quiet bearings have a shorter life.

The fit between the balls and the raceways is called "clearance".
The comment "Quiet Bearings have a shorter life." is not correct.

The measurement of noise levels (quietness) in a bearing is a function
of the roundness of the raceways and the finish of the raceways, the
roundness of the balls and the finish of the balls, as well as the
noise generated by the lubrication. The better the finish of the
raceways and balls, and the better the roundness of the raceway and
balls, means the running accuracy of the bearing is better, therefore
quieter. Measuring noise in a bearing measures the balls as the move
in relation to the raceways. The noise in a bearing is measured by a
transducer that measures the vibration that occurs as the balls move.
That measurement is in micron/meters/second.

I would avoid Japanese; Asahi for instance.

NSK, Koyo and Nachi make good bearings and are Japanese.

SKF used a through hardening steel whereas RHP used a case hardening
process.

There are no case hardened ball bearings that I know of.
You are mixing up ball bearings with Tapered roller bearings.

This guy needs a good sealed for life EMQ bearing.
If he's press fitting the bearing on a shaft on a generator he needs a
C/3 clearacne bearing. Any major brand...SKF, KOYO, NSK, FAG,
Torrington, Etc. will suit his needs.




--
K. A. Cannon
kcannon at insurgent dot org
(change the orgy to org to reply)

Don't worry about the world coming to an end today.
It's already tomorrow in Australia.
-Charles Schultz

tg wrote:
"Clive George" wrote in message ...

"tg" wrote in message ...

Define "best". Longest lasting?


yeah, longest lasting


LOL Don't we all. However as you don't disclose the environment or
the usage of this generator and as these bearings are common as
dirt with a price to match I don't see why you're so concerned.
Any name brand will serve the purpose. As for upping the grade,
the oem may not have made the product to such a degree that higher
grade bearings would be suitable and have a shorter service life
as a consequence.
With bearing dimensions of 15 x 42 x13 mm, this generator isn't
going to power a city. A matter of KISS.

Tom

--
Posted via a free Usenet account from http://www.teranews.com

In message ,
Ignoramus13628 writes
On Tue, 2 Jan 2007 18:58:16 -0000, tg wrote:

"Ignoramus13628" wrote in
message ...
On Tue, 2 Jan 2007 18:47:21 -0000, tg wrote:

I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can
get. Thanks for any pointers.



yes, they do come in different grades and qualities. Can you ask the
manufacturer for what they recommend?


I don't trust those girls that answer the phone at the
manufacturers. I'd rather just go for the best I can get - if I can
get advice about what's available. If I ask a local supplier they
will only tell me what they've got, rather than what are the best
type.

I found that customer service reps at manufacturers that I call for
suggestions, are actuially either helpful or can take me to competent
engineers.

i
Give Mercury Bearings a ring

020 8805 1919

Small business who know where they're at


--
geoff

"Tom" wrote in message ...
tg wrote:
"Clive George" wrote in message ...

"tg" wrote in message ...

Define "best". Longest lasting?


yeah, longest lasting
LOL Don't we all. However as you don't disclose the environment or
the usage of this generator and as these bearings are common as
dirt with a price to match I don't see why you're so concerned.

the generator is a wind turbine. The bearings are to a small degree exposed to the elements, or at least the moisture and
constantly varying temperatures of the outdoors. The turbine is high up and getting access to it means erecting a scaffold tower.
All of this is a lot of work simply to replace bearings, thus I want a grade that is going to last. I expect that 'any brand name'
might not serve the purpose, the cheap type might start rumbling or squealing after a couple a months, thus I want to get it right
when I have to re-install the turbine high in the sky. It's no joke assembling a scaffolding tower and then building up the turbine
at the top of it. Ideally I'd like to service the turbine only once a year, or maybe even once every 18 months if possible, and
fitting top knotch bearings might get me that.

In message , Clive
George writes
"tg" wrote in message
...

"Ignoramus13628" wrote in
message ...
On Tue, 2 Jan 2007 18:47:21 -0000, tg wrote:

I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can
get. Thanks for any pointers.

yes, they do come in different grades and qualities. Can you ask the
manufacturer for what they recommend?

I don't trust those girls that answer the phone at the manufacturers.
I'd rather just go for the best I can get - if I can get advice about
what's available. If I ask a local supplier they will only tell me
what they've got, rather than what are the best type.

Define "best". Longest lasting? Smoothest running? For some
applications, the cheapest are the best choice because that's all they
need.


Also, assuming you've decided you want eg the longest lasting ones, how
far up the price/performance curve are you actually prepared to go? If
the normal ones are a fiver,

6203 bearings of the quality you need should cost about a fiver a pair



are you prepared to pay 100 quid for ones which may last twice as long?

This is where you need the experience of a good distributor who knows
their stuff

Manufacturers are not the best people to ask as they will always promote
their product.


(and a side question : I know ball bearings come in different qualities
- do the sealed ones have the same range, or are they rather more
standardised?)


I think 6203-2RSH bearings are sealed on both sides

you could get 6203 Z or ZZ for (single or double) shielded ones

Yes most bearings come in shielded or sealed versions


--
geoff

In message , Tim Lamb
writes
In message , tg
writes
I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can get.
Thanks for any pointers.

Umm... in essence yes. Or rather you get what you pay for:-)

It is 25 years since I had a proper job; working for SKF at Luton so a
certain amount of rust may have affected my knowledge.

.... ...

I would avoid Japanese; Asahi for instance.


I think you must be a bit rusty

most mid range bearings are Japanese nowadays (but made in Malaysia,
Indonesia, Korea etc)



--
geoff

In message , Sylvain VAN DER
WALDE writes

"Tim Lamb" wrote in message
...
In message , tg
writes



snip)

Care is needed when fitting replacements as simply whacking them in with a
steel hammer is likely to cause damage.

Others may care to advise.

Use a copper or brass drift (punch) the same size as the bearing track (a
tube would be best, but you would need a lot of them).


Use the old bearing ...


--
geoff

tg wrote:
"Tom" wrote in message ...

tg wrote:

"Clive George" wrote in message ...


"tg" wrote in message ...

Define "best". Longest lasting?


yeah, longest lasting

LOL Don't we all. However as you don't disclose the environment or
the usage of this generator and as these bearings are common as
dirt with a price to match I don't see why you're so concerned.


the generator is a wind turbine. The bearings are to a small degree exposed to the elements, or at least the moisture and
constantly varying temperatures of the outdoors. The turbine is high up and getting access to it means erecting a scaffold tower.
All of this is a lot of work simply to replace bearings, thus I want a grade that is going to last. I expect that 'any brand name'
might not serve the purpose, the cheap type might start rumbling or squealing after a couple a months, thus I want to get it right
when I have to re-install the turbine high in the sky. It's no joke assembling a scaffolding tower and then building up the turbine
at the top of it. Ideally I'd like to service the turbine only once a year, or maybe even once every 18 months if possible, and
fitting top knotch bearings might get me that.



Rather than worry about "top knotch" bearings, (any good brand will do)
I suggest you concentrate on improving the environment in which the
generator will exist. Namely full enclosure.
Presumably this an automotive based generator, consider the underhood
environment of a car in the Midwest, hot, cold, freezing, dry and wet.
Yet the generator bearings survive...
From a maintenance point of view, you could look outside the square and
design your tower so that the generator assembly could be lowered to the
ground for servicing without actually have to erect scaffolding.
Such designs are commonplace down here. Simple cable operated latches
lock the generators in place atop the tower.

Tom

Tom

--
Posted via a free Usenet account from http://www.teranews.com

"raden" wrote in message
...
In message , Sylvain VAN DER
WALDE writes

"Tim Lamb" wrote in message
...
In message , tg
writes



snip)

Care is needed when fitting replacements as simply whacking them in with
a
steel hammer is likely to cause damage.

Others may care to advise.

Use a copper or brass drift (punch) the same size as the bearing track (a
tube would be best, but you would need a lot of them).


Use the old bearing ...

I've never tried that, so can't comment.

Sylvain.

--
geoff

"K. A. Cannon" wrote in message
...
On Tue, 2 Jan 2007 20:01:12 +0000, Tim Lamb
wrote:

In message , tg
writes
I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can get.
Thanks for any pointers.

Umm... in essence yes. Or rather you get what you pay for:-)

It is 25 years since I had a proper job; working for SKF at Luton so a
certain amount of rust may have affected my knowledge.

Different manufacturers use different steels and hardening methods

All ball bearings are made from SAE 52100 steel.
Check with the ABMA or ISO and see.

which
confer different characteristics to the life and robustness of the
product. Also the fit between the balls and the grooves has a big impact
on the noise and performance. Quiet bearings have a shorter life.

The fit between the balls and the raceways is called "clearance".
The comment "Quiet Bearings have a shorter life." is not correct.

The measurement of noise levels (quietness) in a bearing is a function
of the roundness of the raceways and the finish of the raceways, the
roundness of the balls and the finish of the balls, as well as the
noise generated by the lubrication. The better the finish of the
raceways and balls, and the better the roundness of the raceway and
balls, means the running accuracy of the bearing is better, therefore
quieter. Measuring noise in a bearing measures the balls as the move
in relation to the raceways. The noise in a bearing is measured by a
transducer that measures the vibration that occurs as the balls move.
That measurement is in micron/meters/second.

I would avoid Japanese; Asahi for instance.

NSK, Koyo and Nachi make good bearings and are Japanese.

SKF used a through hardening steel whereas RHP used a case hardening
process.

There are no case hardened ball bearings that I know of.
You are mixing up ball bearings with Tapered roller bearings.

This guy needs a good sealed for life EMQ bearing.
If he's press fitting the bearing on a shaft on a generator he needs a
C/3 clearacne bearing. Any major brand...SKF, KOYO, NSK, FAG,
Torrington, Etc. will suit his needs.

Very interesting and useful.

Sylvain.

--
K. A. Cannon
kcannon at insurgent dot org
(change the orgy to org to reply)

Don't worry about the world coming to an end today.
It's already tomorrow in Australia.
-Charles Schultz

"Newshound" wrote in message
...

Your question reminds me of some interesting info (if memory allows). A
certain British army tank had to rely on a source of Russian bearings, as
they were not available anywhere else, at short notice.
I think that the "cold war" was still on.


I'd not heard that one (sounds a bit Urban Myth to be honest, as Wyko
could make anything at a price, but maybe it was to do with delivery),

As stated above "at short notice". It's definitely not an "Urban Myth". It's
true, and I'd wager on it.

but when I was trying to source asbestos clutch linings to keep an old UK
nuclear power station going I was interested to find that you could still
fit asbestos to Challenger tanks
I don't think that regulations that are mandatory to civilians apply to the
Armed Services.

Sylvain.

In message , raden
writes

It is 25 years since I had a proper job; working for SKF at Luton so a
certain amount of rust may have affected my knowledge.

... ...

I would avoid Japanese; Asahi for instance.


I think you must be a bit rusty

most mid range bearings are Japanese nowadays (but made in Malaysia,
Indonesia, Korea etc)

Yes. I was actually on the electrical side so I refuse to be
embarrassed:-)

SKF took a big hit from the Japanese in the late 70's. My *hearsay*
understanding was that by relaxing the groove tolerances much quieter
bearings could be marketed for use in *quiet environment* electric
motors. In factory scuttlebutt at the time was that this would lead to
shorter life and reduced functional performance.

I have direct personal experience of a particular range from Asahi (deep
groove, self aligning) and believe they are not as good as other
manufacturers equivalents.

regards




--
Tim Lamb

tg wrote:
"Ignoramus13628" wrote in message ...
On Tue, 2 Jan 2007 18:47:21 -0000, tg wrote:

I have to replace some bearings in a generator I have. I discovered
they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the
same? I want to replace these bearings with the best I can
get. Thanks for any pointers.


yes, they do come in different grades and qualities. Can you ask the
manufacturer for what they recommend?

I don't trust those girls that answer the phone at the manufacturers.

You should. You'ld be amazed at what a bright girl can pick up at an
engineering company..apart from a 'dose' of course..

tg wrote:
"Tom" wrote in message ...
tg wrote:
"Clive George" wrote in message ...

"tg" wrote in message ...

Define "best". Longest lasting?

yeah, longest lasting
LOL Don't we all. However as you don't disclose the environment or
the usage of this generator and as these bearings are common as
dirt with a price to match I don't see why you're so concerned.

the generator is a wind turbine. The bearings are to a small degree exposed to the elements, or at least the moisture and
constantly varying temperatures of the outdoors. The turbine is high up and getting access to it means erecting a scaffold tower.
All of this is a lot of work simply to replace bearings, thus I want a grade that is going to last. I expect that 'any brand name'
might not serve the purpose, the cheap type might start rumbling or squealing after a couple a months, thus I want to get it right
when I have to re-install the turbine high in the sky. It's no joke assembling a scaffolding tower and then building up the turbine
at the top of it. Ideally I'd like to service the turbine only once a year, or maybe even once every 18 months if possible, and
fitting top knotch bearings might get me that.



Go for stainless steel, oil lubed and fully shielded.

If corrosion/dirt rather than actual wear is the problem.

There are various grades of steel used as well.

I can tell you from some time I spent directly involved in making the
things that Toyo were the most exacting specs.

Not sure where you got that info. DuPont did a study on bearing
quality and Toyo (Koyo?)) wasn't even considered. NTN had the highest
quality rating and as a result, DuPont corporate policy is to use NTN
only.

On Tue, 2 Jan 2007 18:47:21 -0000, "tg"
wrote:

I have to replace some bearings in a generator I have. I discovered they are a common size - 6302-2RSH. What I want to know is, do
bearings come in different grades or qualities? Or are they all the same? I want to replace these bearings with the best I can get.
Thanks for any pointers.

Bearings do come in different grades and qualities but most generators
use bearings made to ABEC-1 standards as high precision is not needed.
All that means is that the ID, OD and width fall within certain
tolerances but has nothing to do with surface finish, concentricity
etc. I would definitely stay away from Chinese - some are reasonably
good, some are real trash and you don't know which you may be getting
and the same holds true for India. Any bearing from a major
manufacturer (NTN, NSK, SKF, FAG, Fafnir etc) will suffice however,
NTN has been considered to be a top brand for electric motors for
years. In a DuPont comparison, NTN ranked highest in the world in
quality and adherence to tolerance but the differences are negligible
for all practical purposes. Sealing is another issue - most electric
motor (and generator) bearings are shielded. Cheapest and fairly good
at blocking dirt but doesn't do anything for water. Sealed is best but
a full contact seal creates friction and increases start up torque.
Your best bet for this application would be a non-contact seal such as
the LLB suffix on NTN. A sealed or shielded bearing is also "lubed for
life" so you really don't need to grease it - just run it until it
begins to fail. Most bearing failures are caused by over lubrication.
Also, most manufactures have gone to an "EM" designation for electric
motor bearings which means they have certain qualities preferred for
electric motor applications. This automatically includes C3 internal
clearance for a press fit on the shaft. If the bearing doesn't say EM
then you need to make sure it does say C3. Good luck with your
selection.

On Tue, 2 Jan 2007 23:43:03 -0000, "tg"
wrote:


the generator is a wind turbine. The bearings are to a small degree exposed to the elements, or at least the moisture and
constantly varying temperatures of the outdoors. The turbine is high up and getting access to it means erecting a scaffold tower.
All of this is a lot of work simply to replace bearings, thus I want a grade that is going to last. I expect that 'any brand name'
might not serve the purpose, the cheap type might start rumbling or squealing after a couple a months, thus I want to get it right
when I have to re-install the turbine high in the sky. It's no joke assembling a scaffolding tower and then building up the turbine
at the top of it. Ideally I'd like to service the turbine only once a year, or maybe even once every 18 months if possible, and
fitting top knotch bearings might get me that.

Hi,

Try alt.energy.homepower and maybe alt.energy.renewable, and trawl the
archives of them. There's likely to be good info on maintaining wind
gens at least, and maybe something on the best bearings for them too.

cheers,
Pete.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember
(Tom) saying something like:


I can tell you from some time I spent directly involved in making the
things that Toyo were the most exacting specs.

Not sure where you got that info. DuPont did a study on bearing
quality and Toyo (Koyo?)) wasn't even considered. NTN had the highest
quality rating and as a result, DuPont corporate policy is to use NTN
only.

If that works for them, fine. Toyo are outstanding, imo and experience.

Looking NTN up, as I hadn't come across them, it seems that Toyo and NTN
are very closely tied up anyway.

http://www.ntn.ca/corporate_history.htm
--

Dave

K. A. Cannon wrote:

All ball bearings are made from SAE 52100 steel.
Check with the ABMA or ISO and see.

With the exception of stainless, ceramic, or even Delrin.

How about "Most ball bearings...."?


Kevin Gallimore

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If your bearings are starting to go out after only 2 months, that is
only 1500 hours. And if I assume that many of those hours are not high
load (or no load), I'd say you have a design problem that won't be
solved with a better bearing. Moisture, dirt, axial loads, overloads,
bad mounting surface all come to mind.

I'd certainly be designing my hard to service equipment for 10,000 hours
MTBF with a goal of 20,000 hours. Keep in mind that many fractional
horse electic motor applications (ie furnace fans) have 50k to 100k hour
life expectancies.

tg wrote:
"Tom" wrote in message ...

tg wrote:

"Clive George" wrote in message ...


"tg" wrote in message ...

Define "best". Longest lasting?


yeah, longest lasting

LOL Don't we all. However as you don't disclose the environment or
the usage of this generator and as these bearings are common as
dirt with a price to match I don't see why you're so concerned.


the generator is a wind turbine. The bearings are to a small degree exposed to the elements, or at least the moisture and
constantly varying temperatures of the outdoors. The turbine is high up and getting access to it means erecting a scaffold tower.
All of this is a lot of work simply to replace bearings, thus I want a grade that is going to last. I expect that 'any brand name'
might not serve the purpose, the cheap type might start rumbling or squealing after a couple a months, thus I want to get it right
when I have to re-install the turbine high in the sky. It's no joke assembling a scaffolding tower and then building up the turbine
at the top of it. Ideally I'd like to service the turbine only once a year, or maybe even once every 18 months if possible, and
fitting top knotch bearings might get me that.