Posted by Christopher (24.95.234.251) on March 12, 2002 at 21:28:38:
In Reply to: Gravity Wheel posted by John K on March 12, 2002 at 16:28:28:
John,
Just a small problem with the Rutkowski design:
To balance three balls with one ball you must place the pivot point three times closer to the ball stack than to the one ball. In this configuration the one ball can move down a distance of three balls to raise the three balls a distance of one ball.
The Rutkowski design moves the pivot point closer to the ball stack to get more lifting power from the one ball. Unfortunately that stops the ball stack from lifting as high as it was before. The closer the pivot point is to the ball stack the less the ball stack rises.
If the ball stack is not high enough the one ball will not fit under the ball stack after it rolls over there.
This means you must drop the one ball further to get the ball stack higher, but you are already dropping the one ball to almost horizontal.
If the one ball is dropped lower than horizontal it will not be able to roll uphill to the bottom of the ball stack on its own.
As far as your dumb-waiter idea, you should watch out for the same types of gotchas. It is generally accepted that you use exactly the same amount of energy to raise a weight a certain distance as you get out when you lower it (or one connected to it) the same distance. Also remember that pulleys work exactly like moving the pivot points on levers, you get more lifting power but proportionaly smaller lift distances.
Good luck and remember to have fun or else this wheel stuff will become obsessive! It sure has with me!
:
: Hi everyone,
: This is my first time posting on this page. Just curious, what do you think of the design below ?
: http://homepages.picknowl.com.au/astro1/jan/default.htm
: I'm a little unsure as to how all the pieces of it would function...but maybe together we could figure out if this thing has any merit.
: My father in law and I have been trying to come up with something similar (very much at the primitive stage of development).
: One idea of ours has been to use a 'dumb waiter' to provide a counterweight to the balls that would be lifted up,and placed at the top of the wheel. Of course friction would come into play,so we're trying to find low friction pulleys.
: We're also toying around with setting up the pulleys so that you have a large mechanical advantage to lift the dumb waiter up with. I'm wondering if you had a ball drop from the bottom of the wheel into a little bucket that was at the other end of the pulley, which the dumb waiter was attached to, then the ball falling off the wheel might be able to lift another ball onto the top of the wheel (by lifting the whole group of balls at once).
: I'm not sure if what I've written makes much sense, as I've just kind of plunked it down. But I would definitely be interested in people's feedback on the design I provided a link to.
: Thanks,
: John K