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Forum Index : Windmills : Yaw Bearing Mecanism

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Guest

Joined: 01/10/2003
Location:
Posts: 52
Posted: 07:39pm 18 Jan 2006
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Hello everybody!

I'm an Spanish Industrial Engineering student, and I'm doing my final career thesis about a home-build windmill.
I'm having troubles to find good information about the mechanism that turns the windmill when the wind is to hard (yaw bearing).
I don't understand how can the tail turn the windmill to the good wind direction, when it is lower, if the tail is not fixed to the main structure

I would be really glad if someone could solve my doubts and tell me a website where i could find the way to build it.
 
Chris

Senior Member

Joined: 12/09/2005
Location: Australia
Posts: 146
Posted: 06:56am 19 Jan 2006
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The tail is connected to the windmill structure, ie the actaul blades and generator. This all rotates on a bearing thats connected to your mast which is cemented into the ground. The tail catches wind and moves the entire structure into the direction of the wind.

Im not sure how much that cleared it up, but yeah  Im pretty crap at descriptions. Someone else will probably have a better description.

 
F&P murray

Newbie

Joined: 25/10/2005
Location: Austria
Posts: 22
Posted: 07:17am 19 Jan 2006
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Hi Antoni

most of us use an automobile wheel bearing and hub as our axis as the centre of the windmill. Basically the tail forces the mill toward the oncoming wind by taking the most efficient approach that is straight toward the wind, it is a "cutting system" much like an aeroplane tail keeping the unit straight 

 

probably noy a better explanation but i tried

BOB


Bob from Murray Bridge, SA
 
Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5078
Posted: 09:16pm 19 Jan 2006
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I think Antoni was after information of the furling process.

I'm going to quote from the articles I wrote for Silicon Chip, saves me explaining it again.

" The tail used on our windmill is of the self furling type, which means the tail is designed to turn the windmill out of the wind if the wind speed or load on the windmill blades exceeds a safe point. So how does it work? You will notice the windmill propeller is offset to one side of the mast, by 100mm to be exact. So as the wind blows against the propeller, the whole windmill will want to turn away from the wind. Our tail is on a hinge of sorts. The hinge is angled back and angled out to the opposite side of the propeller. This angle means the tail wants to turn downward and out ( Just like when you are asked to move a mate’s fridge, as soon as you lean the fridge back the door opens and gets in the way ). We have placed a stop on the hinge, so the tail will stop when it is pointing directly back from the windmill.

When the windmill in running in normal winds, the weight of the tail is enough to keep the tail against this stop, and therefore keeping the propeller facing the wind, remembering the tail will always be downwind. As the wind speeds up the force against the propeller will reach a point where it exceeds the weight of the tail. The propeller will start to turn out off the wind, and the tail will turn upward on the hinge. While gravity wants to pull the tail back down, the force of the wind keeps the tail downwind, where it balances against the force of the propeller trying to turn the windmill around.

As the wind picks up the tail will lift higher, until it reaches the top hinge stop. At this stop the tail is almost in line with the propeller, which is almost at right angles to the wind. The furling is adjusted by adding or removing weight from the tail, or changing the tail boom length. If you find your windmill is turning out of the wind too early, try adding some weight to the tail. Or move the tail further out. And visa versa if the tail doesn’t furl earlier enough. This method of furling is very simple and reliable, and has been in use for hundreds of years."

Hope that made sense.

Glenn

 


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Juan Antonio
Newbie

Joined: 19/01/2006
Location:
Posts: 2
Posted: 02:58pm 22 Jan 2006
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Thanks everybody!

Now I have a better idea about how it works.
I hope to build my own windmill at the end.


 
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