Big vawt bearings

[feral air]

Here's the basic idea...

Make a circle about 6' in diameter wherever you want the 'mill. In the center have a wheel sticking out of the ground a little bit (think merry-go-round). Attached to that center bearing will be a large steel carriage that spins in circles on wheelbarrow (or better) wheels. On top of the carriage goes whatever wind-gobbling vawt shape you want.

If it works out right, the carriage should be able to hold 1/2 ton fairly easily and the center bearing won't carry any weight.

I'm thinking that a 1/2 ton weight limit and a 6' (-ish) diameter base should give me a bunch of leg room. It won't be silo sized or anything but it's getting there. Thoughts?

[PHinker]

   I was thinking along the same lines a while ago.  My thought was to use some 10" wagon tires along the perimeter.  You would need a skirt of some sort to keep out debris, snow, and the like.  It probably wouldn't hurt to pour a concrete ring for the outer wheels to run along but it sounds like your rig is meant to be portable.  Of course, this setup would turn fairly slowly and depending on the height, you might have a tipping issue.

[feral air]

I only chose wheelbarrow wheels for their carrying capacity, really. The ones I got (solid tires) are rated for 445lbs each.

I'm not too worried about a skirt. When we get snow it's light and only lasts a day or two and there's not much debris around either (leaves and twigs don't count against wheelbarrow wheels). I hear ya on the raceway though - a concrete ring for the wheels to ride on will help decrease rolling resistance, that's planned.

I'm not trying to make it portable though, no way. Once the center bearing is in, that's where the 'mill is going. I could change the top at some point but once the carriage is bolted to the center bearing it'll be there until the wheels need replacing.

Tipping is something I'll have to look at more as I progress but the center bearing should help act as an anchor. The weight of the loaded carriage could be near 3/4 ton if I wanted, and with a 6' dia. footprint, that should help some too. I dunno yet really.

more later I guess...take it easy

[Stonebrain]

Hi,

Neat idea,put a wooden horse and aa airoplane on it and the kids will have fun too!

The tires will wear out quite fast,because they are not running in a straight line.Better choose a relatif small diam for the wheels and a good pressure to limit the wear out.

If they run on wood they will wear out slower an have less friction then on concrete.

For minimal wear and friction the wheels should run on steel but that's maybe an utopie.

Good luck!

cheers,

Stonebrain

[electrondady1]

i think your on the right track Ferrel air.

this has always struck me as the best way i guy with modest resources could build big

an automotive axle for a central pivot point and then a rotating platform

spreading the load.

it eliminates the need for a top pin and tower as well as guy wires.

the horizontal moment is directed right into the ground

you can build as big as you want

on a 6'dia. the circumference  is 226 " and a 10 " wheel wil have a ratio of 7.2 to one

so why not but the alternators on the support wheels ?

a  4" support wheels will turn at 1000 rpm  if you can get the vawt to turn at 60 rpm.

 

[electrondady1]

make the support wheels a form of caster  to eliminate the wear.

it will still support the weight but will track with out binding .

[feral air]

I ordered solid tires with the wheels so I'm hoping they wear ok. Supposedly they have lower rolling resistance than regular tires and since they're puncture proof and on sale they were the obvious choice. That said, I'll still have to keep an eye out and rotate 'em occasionally of course.

I was planning on painting the concrete raceway to take the edge off and maybe decrease tire wear. If I take the time (/spend the money) I'll probably do a couple thick base coats and then paint it up so it looks like it's riding on a never ending road.

Once I get the tires I'll start thinking about building the carriage. I'm not sure I'm up to the task yet. I might have it done at the shop in town, just so it's perfectly square and makes a perfect circle, yaknow. What sits on top isn't so critical so I've got a start on that. Maybe I'll finish welding that together and give making the carriage a shot, I dunno yet.

Still a long time coming but I've got something of a start anyway.

[feral air]

What's the easiest/best way to get the power off the rotor?

I'd probably still want to gear it off the wheels but that wouldn't be as bad as what I anticipate any other way. hmm...

[rippersoftware]

Someone on the board posted a VAWT picture where the underside had a bicycle chain embedded on the inside of a circle cutout.  Kinda a reverse gear.  The various DC servo motors were geared and mounted to run from this embedded chain.

Pretty high gear ratio and didn't require alot of VAWT speed.  Yet it appeared to produce quit abit of torque due to the size of the VAWT.

Others have shown a tire mounted to the center shaft and the generators hinged on an arm and held in place with springs so that the shaft of the generator was being turned by the tire which was being powered by the VAWT.  The generator shaft had a rubber tube press fitted to the shaft for traction.  Fairly high ratio there too.

Hope it helps.

RipperSoftware

[feral air]

Now that my wheelbarrow wheels are paid for and on their way, I found better wheels....

Here's a link.

I think I'm gonna try and sell the wheels I'm getting so that I can get those casters instead.