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Forum Index : Windmills : 25 000 watt homebrew

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solarmike

Newbie

Joined: 14/11/2005
Location: Canada
Posts: 26

Posted: 06:01am 14 Nov 2005

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I found a transport truck rear differential for $300 and I am going to lock out one of the half axles and make use of the already built in drum brake. The gear ratio is 8:1 and I am going to mount a 50 Hp salient pole synchronous motor to it. I will try different blade lengths to find out how much power I can get out of this beast. The tower is something i must build myself. I am a welder.

I am not going to pay $100 000 for a 40Kw machine. I would rather build one. whada ya think? I just sketched this in two minutes to illustrate

I am solarmike

Chris

Senior Member

Joined: 12/09/2005
Location: Australia
Posts: 146

Posted: 06:30am 14 Nov 2005

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I wouldnt use a differential from any car, they have to much resistance for windmill application due to oil and stuff like that. You would be better off making your own gearbox that converts to 90 degrees or mounting your motor directly onto the blades shaft...

solarmike

Newbie

Joined: 14/11/2005
Location: Canada
Posts: 26

Posted: 06:45am 14 Nov 2005

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Chris said I wouldnt use a differential from any car, they have to much resistance for windmill application due to oil and stuff like that. You would be better off making your own gearbox that converts to 90 degrees or mounting your motor directly onto the blades shaft...

Since I will have a swept area of about 300 square feet it won't make much difference. I have been upclose and personal with 60 Kw Danish "windmatics" and enertech '15/50' 40 Kw machines and they have even larger oil filled gear boxes. also the Jacobs machine uses a similar design and it has a 6.1:1 90 degree vertical shaft generator.

The wind will overcome the friction losses. plus if a failure occours then i can buy replacement parts. Thanks for your input.

I am solarmike

Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5078

Posted: 07:09am 14 Nov 2005

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With respect to using a car diff, have a think about the internal oiling. At normal angle, ie in a car, the crown gear sits in a bath of gear oil. This splashes the oil around the casing and lubricates the pinion and spider gears. Oil is also splashed down the axle tubes ( also helped when the car corners ), and into the wheel bearings.

When you tip over the diff for your windmill, you may need to add some extra oil, enough for the crown gear to sit in. There may be a problem with oil leaking out the pinion shaft seal too. And you need to make sure some oil makes its way down the axle tube to the wheel bearing.

Other than that, it looks good. The old car diff is built pretty strong and your big blade will have no problems turning it.

Glenn

The best time to plant a tree was twenty years ago, the second best time is right now.
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Storm

Regular Member

Joined: 12/09/2005
Location: Australia
Posts: 43

Posted: 02:01pm 15 Nov 2005

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Definantly the first thing I thought about when considering using a diff was the pinion seal will leak before to long especially if you put more oil in to keep the oil up to the gears, I was thinking of using a datsun independent diff as they have short shafts, but moved away from the whole idea soon enough.

But maybe you can tell us all when you get it working eh?

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