"Permanently" Lubricated Bearing?

[YoshiMoshi]

TL;DR Summary

What are permanently lubricated bearings?

One of the bearings in my alternator is loud and noisy. Instead of just replacing the whole alternator, I was thinking of just pressing in a new bearing. I started looking at some online vendors, and saw that McMaster Carr has permanently lubricated bearings? This is the first time I have heard of such a lubricant. Is the extra cost worth it, is it really permanently lubricated? I mean if I don't have to worry about the bearing going bad again, it might be worth the extra cost. I only know of bearings that are lubricated with grease. Not exactly sure about this type of lubricant is and what applications these type of permanently lubricated bearings are used. I can read what it says, solid polymer lubricant, is it ok to use such a lubricant for an automotive application where it might spin a few thousand RPM? I didn't know "permanently" lubricated bearings existed.

 

[Lnewqban]

Your application is mainly affected by heat from the engine.
The shown bearing is more resistant to water contamination.
The polymer is not the lubricant, it functions as a "sponge" to retain the lubricating oil and to keep contaminants out.

Please, see:
https://baartgroup.com/what-is-solid-lubrication/

 

[Baluncore]

You must replace the bearing before the armature begins to hit the stator, or the windings will fail. Look for contact marks where the metal has been polling, if you see any, replace the entire alternator.

Any pre-lubricated sealed bearing will solve the alternator noise problem. It does not need to be anything special. It will be a common deep groove ball bearing, probably 62xx with a suffix of -2R or -RR, as it has two rubber seals. You should also replace the bush or bearing at the slip-ring end at the same time. Replace the brushes for the slip rings at the same time.

 

[jack action]

It's a technology that has been available for decades. If you have a bearing that you do not lubricate, chances are it is a permanently lubricated bearing. Here's a corporate video explaining how they work:

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As for their usage, they are rated just like other bearings: radial load, maximum speed, temperature range, etc. The referenced McMaster-Carr bearings in the OP do have those ratings in their catalog. You can compare them with traditional bearings if you wish.

 

[anorlunda]

It's a technology that has been available for decades

Thanks for sharing. That video was very informative. I had never thought before about the pitfalls of manual lubrication.

 

[Averagesupernova]

If you can find a place that rebuilds starters, alternators, etc. they will likely stock the specific bearing you need.
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I've had better luck having a local shop that specializes in that sort of thing do it rather than buy a rebuilt at an auto supply store. Also, when you disassemble many alternators it's difficult to keep from contaminating the needle bearing on the butt end of the alternator. Usually cheaper to replace that also while you're at it.
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So then the question is how far do you want to go? If it's not brushless, you might as well replace the brushes too.