913 bearings.

[Allan]

Hi, I'm going to be changing the bearings on our Rutland 913 and would like to buy them in advance. The last time I did the job, on a different unit, I used SKF "green" bearings. These are supposed to offer less resistance. Does anyone know the number or sizes of the bearings required?
Allan

 

[<152587>]

6202zz for the generator, 6202zz and 6203zz for the yaw axis

 

[pvb]

6202zz for the generator, 6202zz and 6203zz for the yaw axis

Rutland suggest using 6202 2rs bearings for the generator, and for the upper yaw bearing. These are rubber-sealed, and presumably offer more protection against the elements than the 6202zz metal-shielded bearings. I'd be tempted to go with Rutland's recommendations, but buy them elsewhere obviously!

https://www.marlec.co.uk/rutland-913-spares

 

[RIBW]

See
http://www.ybw.com/forums/showthread.php?360584-Any-bearing-experts
It is worth a read. Marlec fit Nachi6202NSE for the reasons given in the posting. 4 years after my Marlec refurbishment, the front bearing is kn**red but the rear bearing seems fine.
I am replacing the bearings this time. I bought SKF62022RSL for the genny based on the reported unofficial opinion from Marlec and after asking Simply Bearings what to buy for the best quality. Both advised SKF.
This morning I stripped the front bearing balls and races to investigate why it was so 'crunchy'. The outer race has one small patch of rust/abration but the inner race is 75% corrupted. (I never tethered the blades - reportedly a common cause of bearing failure). The balls and rubber/metal seals looked good.
I am hoping that the SKFs will perform better (never trust in hope!). Time will tell.
Cheers
Bob

 

[RIBW]

Since my post yesterday, I've been looking into why my Nachi bearing corroded so.
It seems that standard bearings are made of chrome steel and are liable to corrosion. Stainless steel versions versions are available
[ https://simplybearings.co.uk/shop/p...aring-15x35x11mm/product_info.html?backstep=1 ]
at ~3x the price of their chrome cousins. Their description says they are suitable for the marine environment"but will rust eventually".

As the 2013 posting asked - are there any bearing experts out there?

Refurbing a windgenny is not one of those jobs that I am keen to regularly repeat.

Any thoughts anyone on the worth of using the stainless bearing?
Cheers
Bob

 

[nrcoyle]

The problem with the most stainless bearings is that they are not the most corrosion resistant grade of stainless as it is a trade off with strength and hardness.

316 grade bearings are available https://www.amazon.com/SMR6202-2RS-15x35x11-Stainless-Radial-Bearing/dp/B00DMG509U but they may have some strength/hardness issues.

Another potential option is a ceramic bearing such as

https://www.bearings-online.co.uk/i...MI2OzU36yj3AIVz73tCh1BaQR_EAQYAyABEgJQZfD_BwE
(no connection just the first suitable product google spat out)

which should have no corrosion issues at all. I have not used these in this application but have used them to replace bearings in a wind indicator with good results.

 

[Allan]

I'm really grateful for all of the help, thank you. My first thought, reading through the thread was that, with stainless and ceramic coming into it, it's become more complicated. Now I've looked at the Simply bearings website, I've decided I will buy 4 x SKF 62022RSL @ 6 quid each. That gives us a couple of spares in case they need replacing while we're away sometime. I'm thinking of covering them with grease to keep the air and water off them as much as possible.
Any more thoughts will be appreciated, I'm happy to change my plans!
Allan

 

[RIBW]

..I've decided I will buy 4 x SKF 62022RSL @ 6 quid each.

Despite all my background reading, I too will be using those £6 bearings. Having invested in all the necessary bearing pullers/separators and the Loctite gunks, it means I'll just be renewing as soon as a rumble is detected.

I'm thinking of covering them with grease to keep the air and water off them as much as possible.

Today I took apart the rear bearing - it was running smoothly and the races and balls are unblemished - so different to the front bearing which is, physically, in the same environment. The only cause of the difference I could imagine is that there is a blind cavity in front of the front bearing whereas the rear bearing looks as though it will freely drain. This front cavity is shaped so it could possibly retain water, laced with the inevtable quantity of salt from spray etc. I will be packing this area with grease; the amount will be determined to get best fill without causing hydraulic pressure on the front of the bearing.

[It is not obvious why the front cavity is blind - if it was open, the nose cone would stop any direct ingress and the bearing could drain!?!]

Cheers
Bob
P.S. Also in Bristol

 

[RIBW]

Just a quick update:-
Bearing removal: A bearing separator (I used the Screwfix item which came complete with a puller) was absolutely necessary for the front bearing. However the internal puller I bought specially for the job was useless on the rear bearing which would not move. In the end I knocked the rear bearing out from behind quite easily.

Bearing replacement: Both new bearings re-asembled on the inner race very well but when the magnetic housing was re-assembled, there was enough play in the shaft (suspending it in the hand and allowing the considerable weight of the magnets to be taken by the bearings) to cause a scraping interference which slowed the rotation and, no doubt, would have worn away the copper coils in the stator. After separating the magnets again, it was clear that both the front and back faces were interfering and that something had to be done to eliminate the interference.
I tried plumbers tape around the front bearing outer race and shims between the magnet assemblies. Neither cured the interference. I then took notice of what looks like a sprung shim on the rear assembly. It faces up to the outer ring of the rear 6202 bearing. It looks a little rusted and would not move. I therefore thought I should shim out the rear bearing more but no one seems to stock bearing shims of the right size (35x30xXmm), I have therefore bought 35odx2.5mm nitrile O-rings to try.

Has anyone any other suggestions on how to eliminate the interference. (Going solar is already in place!)

Cheers
Bob

 

[Allan]

I changed mine yesterday morning. The front bearing was simple but the back bearing took a little longer as I couldn't use a puller. I had no problem with the rotor touching.
I put grease on all the bearing faces, hopefully that will help protect them. I think the centrifugal forces will soon move it though.
Allan

 

[RIBW]

Mea Culpa,
I failed to clean out the old Loctite from the rear bearing. Once I had done that, a sprung bearing washer came away easily. After a good clean up, there was no interference. All is smooth!
Cheers
Bob