Low rpm high torque water wheel

So this is my question. If I have a very wide water wheel, say 12ft wide vs 1ft wide. Will that give high torque?

- Wider ( and possibly deeper 'Buckets" ) will allow you to catch more of the water flow than a narrower wheel will, Depending on your location, the time of the year,

and the resulting amount of stream flow you could have more water running in the stream than you can use.

Does your site provide year round flow, or can you place a Dam upstream from your water wheel to hold back some/most of the total flow to hold it in reserve for

your local dry period(s)

AT THE BOTTOM OF THIS PAGE IS A LIST OF '' SIMILAR THREADS " ALWAYS CHECK THERE FOR MORE USFULL INFORMATION AFTER YOU POST !



For the good of the crafts ! Big AL

Not really, Torque comes from the lever arm length, a 12 foot diameter wheel 1 foot wide would have more torque than a 12 foot wide wheel 1 foot in diameter.

Rhys is right; going from a 1ft diameter to a 12ft diameter would also lower the RPM by a factor of 12, assuming the resistance of the wheels is equal.

The other thing to keep in mind is that an overshot water wheel will provide better efficiency than an undershot, providing more bang for your flow... but this does limit wheel size in some situations. I think a breast-shot wheel is somewhere in between for efficiency.

Thanks everyone. That's what I was thinking. It's a wide but somewhat shallow river. I'm in a great spot thou. There was a dam there at one time. So almost all the stone wall is in tact. Even in a dry season there should be plenty of water for this. I'm thinking as well because the river drops about 12-15ft naturally over 50-75 yards I can rout a portion of water in some type of aqueduct to my wheel and posibably hide the wheel under ground completely if not partially. Next question is how big of a wheel X water do I need for 2,000Watts wheel?

The potential HP of a water wheel is apparently Head(in feet) * Flow(In cubic feet per minute)/540. (http://www.waterwheelfactory.com/horse.htm)

If your entire generation process (from flowing water, through the water wheel, through the generator, through the wiring, through the charge controller, and back out of the battery bank and through the inverter... or whatever your system is) was 50% efficient, you'd need about 5.2 gross HP to make your 2KW.

So, to work back from that, and your head of 15ft: 5.2*540/15=187.2CFM flowrate, or about 1400 US Gallons per minute. So, you'd need a wheel big enough to pass that volume of water... assuming you have that much flow available.

How big that is in actual dimensions, I have no idea... and that 50% efficiency is just a wild guess, too.


2000 watts continuously is quite a lot of power; do you have extravagant power needs? Are you planning to have a battery bank charged by this power? Even a relatively small battery bank would allow for heavier loads for short periods of time, lowering the wattage required to be continuously generated...


EDIT: Found this, which explains how to determine sizing... also contradicts the previous power calculation. Hmm... http://www.backwoodshome.com/articles/behrens18.html

Ive read several different calculations on oversho waterwheels from getting 61 hp with a 10 foot diameter 5 fott wide 1 foot deep buckets witha flow of 50 cfs thats over 370 gallons a second seem unlikely to be possible another said for a overshot wheel that between .3 to 9.0 cfs is the range of flow another said 54 hp xould be reached with 422gpm abot 2.0 cfs on a 6 foot whee im new to this but im thinking with a overshot wheel once it gets moving the buckets wont have time tp completly till and that only about a third of the bucket are filling to spin the wheel that a 6 foot wheel with 18 paddles 1 foot wide and 1 foot deep and a flow rate of 2cfs the wheel should spin about 29 rpm the maximum firba overshot wheel what are your thoughts

Hi Peter;    Welcome to Permies!  
Those are some calculations you have there.  
As this is an older thread the original poster may not be watching any more.

Do you live with a hydro unit?
Most like mine, are high pressure micro hydro.
We do have one member in France hoping to get a vintage overshot water wheel producing power again.

If you have a hydro then tell us all about it, with photo's please.
If not then tell us what your dreams are for water power in the future.

My dream/notion for hydro is a portable, floating undershot wheel setup.

It has to break down to fit into the back of a small vehicle.

I would set it in the current of a nearby river to charge assorted batteries, run tiny motors (slow grinder, knife sharpener, felt polishing wheel), boil water for afternoon coffee, and stimulate conversation.

I might even fish for entertainment, though I never catch anything. The fish just write sympathetic notes and leave them on the hook after stealing the bait.

The generators must be made from scrounged items (cordless drills, DC treadmill motor).

I call it the River Excursion Module (REM), in honour of the Lunar Excursion Module from moonshot days.

Ok so if i 30 rpm on a 5 foot waterwheel with900 gpm 1 foot wide with 16 - 2 gallon buckets hoe much hp woulf inget