Crimedog

Alright folks, time to pick your brain on this one...

Anybody know of an efficient gear reduction system that is relatively small? We need to spin an alternator by human power and want the alternator to be spinning around 3-4K RPM. It's for a project for school and all I can think of is just a system of regular tooth gears... Any smart folks out there want to share some ideas? It would be much appreciated!

tool

Can you rig something up with an old bicycle?? Maybe an old 10 speed or something? when it is in 10 you could run another chain off of the big sprocket on the driven end and have a small sprocket on your alternator, I think 3-4K might be an issue but you might get fast enough to produce power.

Besides I don't think 1 person can spin an alternator under load at 4000 RPM under load, how much current do you need to produce??

dodgezilla04

put a flywheel on it too, might help with the varying load.

Fronty Owner

depending on the power you need to produce, I would lean towards a multi-gear system.
optamistically, your going to be able to peddle at about 60 to 100 RPMs.

Jeff in TD

I like the roadbike idea...

Maybe it could be set up like a stationary trainer. Most of them clamp onto the rear quick release axle to hold the bike up, and run a roller off the rear tire. Others, like my Minoura, run rubber drive wheels off the rear rim's braking surface (for less slip, and no wearing out expensive tires).

Resistance is typically provided by a magnetic unit, or fan, or a fluid resistance unit. The rim drive unit uses a little cog belt between the roller and the resistance unit, so it might be possible to rig something that way.

Otherwise, if you can come up with a road bike (or a mountain bike with rock slicks) and a trainer to hold it up, maybe you could rig up a roller on the alternator, or perhaps running the tire on the regular alternator pulley would work.

As a plus, you would have the bike's range of gears to play with to find one that's efficient.

Anyhow, here's a link to some trainers... and good luck.

http://www.minoura.co.jp/trainer-e2.html

JKM

Where is Beagle1 when we need an "out of the box" idea?

Fronty Owner

does it have to be human driven?

What about driving the alternator from another motor.

Drive a higher voltage DC generator and run it thru an inverter to drive an AC motor to run your alternator?

If you want to use the stationary bike, remove the tire from the wheel and use that as your "large" pulley to drive a smaller pulley on your alternator.

Whats the challenge anyway?

SRTchris

i think the bikecycle gearing is the way to go, but with 3-4k you may ahve to run 2 or even 3 sets of sprockets and chains , kinda like havin a 30speed

Jim Lane

I have built one like this, it is the typical design everybody is using.

http://www.windstreampower.com/humanpower/hpgmk3.html

I used a DC motor from an old winchester drive for the generator.
Jim

Dave88LX

Here's an idea...I'm not sure which gear/pulley it would need to be on, but what about making it heavy? It would be harder to spin up, but once moving, the inertia would keep it spinning easier?

Crimedog

It's for an engineering project, we're using electical power to boil and distill a liter of water. It has to be 100% human powered. Right now the bike gears are looking like the way to go... they're cheap and pretty efficient. Yeah, where is Begle1 when you need to think outside the box