Posted by TomCat on February 16, 2010, 12:27 am
On Mon, 15 Feb 2010 11:53:56 -0800 (PST), harry
>> I'm building a VAWT. It will have a very slow speed, high torque.
>> So to be effective, I'm going to need to gear it up for speed.
>> Average wind speed in this area is 9.8 miles/hour. My turbine
>> would be turning at about 12 RPM. So I'll likely need some very
>> long V-belts. What's the longest they make, like for a very big fan?
>> Has anyone used flexible cable for something like that?
>Once you pass the five or six to one ratio, belts and chains don't
>work at all well. At least trying to do it in one step. You'd be
>better looking at some sort of gearbox. Salvaged from something with
>an ICE but used the other way round.
>Or gearbox and belts, depends what you can find,
I am just curious, why is a belt or chain system not desirable once
you pass the 5 or 6 to 1 ratio. I am not much of a mechanical engineer
and can't seem to get my mind around that.
Tom
Posted by Bob F on February 16, 2010, 2:53 am
TomCat wrote:
> On Mon, 15 Feb 2010 11:53:56 -0800 (PST), harry
>>> I'm building a VAWT. It will have a very slow speed, high torque.
>>> So to be effective, I'm going to need to gear it up for speed.
>>> Average wind speed in this area is 9.8 miles/hour. My turbine
>>> would be turning at about 12 RPM. So I'll likely need some very
>>> long V-belts. What's the longest they make, like for a very big fan?
>>> Has anyone used flexible cable for something like that?
>>
>> Once you pass the five or six to one ratio, belts and chains don't
>> work at all well. At least trying to do it in one step. You'd be
>> better looking at some sort of gearbox. Salvaged from something with
>> an ICE but used the other way round.
>> Or gearbox and belts, depends what you can find,
> I am just curious, why is a belt or chain system not desirable once
> you pass the 5 or 6 to 1 ratio. I am not much of a mechanical engineer
> and can't seem to get my mind around that.
It could have to do with how 'many teeth'/'much belt length' gets engaged on the
smaller wheel, unless the wheels are far apart.
Posted by harry on February 16, 2010, 3:33 pm
> TomCat wrote:
> > On Mon, 15 Feb 2010 11:53:56 -0800 (PST), harry
> >>> I'm building a VAWT. It will have a very slow speed, high torque.
> >>> So to be effective, I'm going to need to gear it up for speed.
> >>> Average wind speed in this area is 9.8 miles/hour. My turbine
> >>> would be turning at about 12 RPM. So I'll likely need some very
> >>> long V-belts. What's the longest they make, like for a very big fan?
> >>> Has anyone used flexible cable for something like that?
> >> Once you pass the five or six to one ratio, belts and chains don't
> >> work at all well. At least trying to do it in one step. You'd be
> >> better looking at some sort of gearbox. Salvaged from something with
> >> an ICE but used the other way round.
> >> Or gearbox and belts, depends what you can find,
> > I am just curious, why is a belt or chain system not desirable once
> > you pass the 5 or 6 to 1 ratio. I am not much of a mechanical engineer
> > and can't seem to get my mind around that.
> It could have to do with how 'many teeth'/'much belt length' gets engaged on the
> smaller wheel, unless the wheels are far apart.- Hide quoted text -
> - Show quoted text -
The above is exactly right. The gear ratios on pedal bikes are not
high.
Posted by vaughn on February 16, 2010, 7:48 pm
>The above is exactly right. The gear ratios on pedal bikes are not
>high.
I haven't counted teeth, but the top gear on my 21-speed certainly exceeds
the 5 or 6 to 1 mentioned earlier. And it isn't even technically a road bike.
Vaughn
Posted by Bob F on February 16, 2010, 8:27 pm
vaughn wrote:
>> The above is exactly right. The gear ratios on pedal bikes are not
>> high.
> I haven't counted teeth, but the top gear on my 21-speed certainly
> exceeds the 5 or 6 to 1 mentioned earlier. And it isn't even
> technically a road bike.
I don't think that's anywhere near the ratio being considered here.
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>> So to be effective, I'm going to need to gear it up for speed.
>> Average wind speed in this area is 9.8 miles/hour. My turbine
>> would be turning at about 12 RPM. So I'll likely need some very
>> long V-belts. What's the longest they make, like for a very big fan?
>> Has anyone used flexible cable for something like that?
>Once you pass the five or six to one ratio, belts and chains don't
>work at all well. At least trying to do it in one step. You'd be
>better looking at some sort of gearbox. Salvaged from something with
>an ICE but used the other way round.
>Or gearbox and belts, depends what you can find,