principles of leveraged rotation

[clarkepeters]

I'm not an engineer but I like to make mechanical inventions. I have a question regarding the ability to leverage rotation. I don't expect anyone has time for lengthy discourse, but if you could clue me in on the basic or particular design principle behind it, I can do the research myself.
Let me describe what I would like to do--if it's even possible. A yoyo will make a single rotation if the string is pulled exactly the same distance as the circumference of it's axis (around which the string is wrapped). What I need to design is, for sake of example only, a yoyo, mounted on an extended axis, that rotates several times, rather than only once, when the string is pulled the same distance as the axis' circumference. I understand that it will probably require gears and extra work (energy) but I need to know if it is even possible and what would be the design principle behind it so that I can look it up and inform myself on the principle--if it is possible.
Thank you in advance.

[clarkepeters]

I've been thinking on this for days, but just as I made this post I think it dawned on me how to do it.

I have the yoyo on an extended axis. To get more rotation for the same distance pulled string (work/force), I will need an additional axis that will hold the gears that will help me get more leverage.
We can assume for the sake of ease that the axes are the same diameter. I will now attach the string (work/force) to the additional axis. This additional axis will have a gear that is, say, three times the circumference of the original yoyo axis. If the gear is connected to the yoyo axis, then when I pull the string the distance of the circumference of the original axis, the outer edge of the larger gear must travel further distance, hence, making the yoyo axis rotate three times the distance, or thereabouts, on a single pull.
Am I right? or close?

[PinkertonD]

Welcome to the forum Clarke, and also welcome to our world. It is not uncommon when you fully describe a problem that you begin to see the solution for it.

Does the string have to be around the outer circumference?
Does it have to be only a single turn?
A conventional yoyo has a small diameter rod inside that the string is wrapped around and that provides as many starter spins as you can get wrapped.

If the string has to be wrapped only once then you will require gearing up to produce more spins from a single starter. The first problem that arises is that gearing some up (depending on ratio) will require many times the input effort to a single turn of string for multiple output spins. The Over-drive unit works like that in cars etc. The final drive is usually about 0.86 : 1 or worse and that's why at the slightest rise in road incline, the auto shifts out of overdrive and back into top gear which is 1:1

So, while your design approach is to get more spins from a single starter turn, be aware that it will require a good deal more input effort.

Having said that, you describe a larger diameter wheel for the string which will mitigate (to some or all effect) the required effort so it all may work for as described in this second post.

Given our new and stupid Patent Laws, I can understand you not wanting to divulge more detail, but if you provide us with more detail we can provide you with more definitive information. You sound to be on a good starting track with the second post though.

[Kelly_Bramble]

Well, I'm sure gyroscopic forces are involved in the operation of a yoyo. -> http://en.wikipedia.org/wiki/Gyroscope .

So, I think I would start there for the calculations or amplified yoyo rotation mechanism.

[clarkepeters]

thank you for your responses.
I didn't mean to be too cryptic. I was just trying to stick with the basic ideas. What I'm actually doing is creating something like a paddle boat, where a person sits and pushes the pedals and the paddle fan (or whatever it's called) will rotate two or three times for every pull of the chain or cord that is equal to the circumference of the axis. This boat won't actually be in water so we don't really have to worry about the water resistance.
At any rate, I don't know why I didn't use bicycle gears as my model--where was my mind at? I think it's because I won't be using circular motion, rather I'll be using an unusual see-saw elliptical kind of motion.
At any rate, gear wise, I realize now that I was just trying to reinvent the wheel -- literally. Now that I've got the bicycle ten-speed type gear model in my mind, I think I should be okay.

Thanks again for taking time out to help me. You are so considerate.

[PinkertonD]

Thanks again for taking time out to help me. You are so considerate.

Happy to help, would love to see pics of the device when complete. Remember, no pics, didn't happen.