bearings: different grades & qualities

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

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.
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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
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Give Mercury Bearings a ring
020 8805 1919
Small business who know where they're at
--
geoff

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wrote:

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
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yeah, longest lasting
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tg wrote:

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
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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.
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tg wrote:

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
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tg wrote:

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.

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wrote:

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.
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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:

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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

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

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.

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

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wrote:

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.
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Sylvain VAN DER WALDE wrote:

What do all those other bearings have to do with it? He needs 6302s. Those aren't tapered roller bearings, needle bearings, thrust bearings or the like.
GWE
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tg wrote:

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

6203s are very common and inexpensive bearings. You can get those in the price range from $2-3 at the low end to maybe $12-15 at the high end. Just ask the guys at the bearing house you buy from. This is certainly a case of you get what you pay for.
FWIW a generator shouldn't need super quality bearings. If it were me I'd get the el cheapos. They will last for many years.
GWE
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We were somewhere around Barstow, on the edge of the desert, when the
saying something like:

They certainly do.

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

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