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chris_psmith
New Member
United Kingdom
81 Posts |
 Posted - 14/01/2008 : 12:28:53
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Anyone any experience of how much a pillow bearing will free up with time. My VAWT will be using three of them, the bearings (for 20mm shaft) have what i would consider high friction, if you spin the turbine it will do about 2.5 revolutions before it stops.
The bearings are apparently tripple sealed, which is where i assume the friction is coming from. If they don't free up considerably i can see a big hit on my efficiency coming up.
Another side effect of this friction is that it is almost impossible to staticaly balance the turbine as the friction far outweighs the weight difference, will have to try without the bearings.
Regards
chris
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Del
Junior Member
United Kingdom
369 Posts |
Posted - 14/01/2008 : 12:41:01
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I've got a load of pillow and flange bearings (I must get around to ebaying them at some point) and i know what you mean about the friction. Beautiful smooth bearings but not exactly free running. I suspect they don't free up much due to the sealed for life nature.
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fungus
Moderator
297 Posts |
Posted - 14/01/2008 : 12:43:04
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| You can take the bearing seals off and run them like that, they will need a little more maintenance but will be free-running, the bearing seals do introduce a lot of drag. |
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chris_psmith
New Member
United Kingdom
81 Posts |
Posted - 14/01/2008 : 12:44:56
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| Fungus, if you are speaking from experience, any idea how you get the seals off, couldn't see anything obvious when i looked, just what looked like a bit of rubber poking out? |
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fungus
Moderator
297 Posts |
Posted - 14/01/2008 : 12:47:44
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| It depends on the bearing case how easy it is to get out but if you can see the seals between the two races then its just a matter of a screwdriver to pry it out. Another thing; the sealed ones usually use grease which is basically a solid until you put pressure on it so at higher rpm's there might not be so much drag, just a thought.. |
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Del
Junior Member
United Kingdom
369 Posts |
Posted - 14/01/2008 : 12:50:23
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| Your seals may not be rubber. The ones on my flage bearing (yaw bearing) I though were rubber but are actually steel. |
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fungus
Moderator
297 Posts |
Posted - 14/01/2008 : 12:56:28
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| Just a thought; you could try replacing the thick grease with a thinner oil for lubrication, it might be less drag , not too sure though |
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Bearing Friction
