Gravity Wheel Idea

[Skipper]

I know a gravity wheel could be made that will produce circular motion, but I don't know if enough meaningful work could be produced.  It will spin (spin sounds like it means a fast rotation and speed is not truly what I expect) but almost has to be in a frictionless environment, thus may not work under a load.

We start with two spokes one at 90° and another at 45°.  We have a heavier weight on the 45° and the lighter weight on 90° spoke is 66% of the heavier weight.  The weights are connected by a pulley system so as the heavy weight moves towards the axle at 45° the lighter weight moves away from the from the axle at 90°.  That's on the top, on the bottom the angles are technically the same (really 270° and 225°) and the weights move in the opposite direction.

The distance moved by the weights is the same.  The heavy weight is fully extended 75% on one side and 25% on the other, while the lighter weight is fully extended 100% on one side and 0% on the other.  What's more important is that on one side 25% of the time both weights are at the closest to the axle and on the other side 25% of the time both weights are furthest from the axle.

A latch, just like a door knob, is needed to ensure the heavy weight doesn't start to shift until it reaches the 45° angle where the rotation then turns the latch. Additionally, once the heavy weight has been released and while the weights are shifting locations the rotation of the wheel should be paused. 

To ensure there are always spokes inside the unbalanced area you want to have more than eight separate pulley systems in the wheel.  The amount of imbalance between the two sides of the wheels is not that significant, so the mounting for the pulley systems needs to be as light as possible, as not to negate the amount of imbalance.   

Different size weights (percentage of difference) could be used, which then requires different angles, and then a different number of spokes.  The larger the distance the weights move the better, and in general more spokes are better.   Also just changing the angle (or the difference in weight) affects wether the pulley system or the rotation can handle more load.  Since the pulley system should have less friction the angle could be changed to 42°, increasing the rotation ability. But at 41° the pulley system won't work even if it was frictionless.

[TinselKoala]

Sigh.
No disrespect intended, but your wheels won't work, magnet assisted or otherwise.
The reason is that, as PurePower suggests in his post, gravity is conservative. That means that the potential energy in a mass depends only on its mass and its height (PE=mgh) NOT on how it got there. You lift a mass by whatever means to the top of its arc on the wheel. That takes exactly as much work as the mass will deliver on its way down to the bottom of its arc. It does not matter if it goes up closer to the axis or farther away, its PE at the top is the same, and the work available coming down is always equal to the work it took to get it up there. Since no system is frictionless, and there are other losses, what you get out is always going to be less than what you put in.
Now, this conservative aspect of gravity also extends to magnetism. The fact that there is a repulsive modality for magnetism only makes the situation a bit more complex, but it is still fundamentally the same. The magnetic PE at any point depends only on position and field strength (analogous to height and mass), not how you get there.
You might like to download my video on testing the Mondrasek magnet-assisted gravity wheel. It shows some ideas for construction, as well as a good way to test your wheels, magnet or gravity or other.
http://www.mediafire.com/?wuldel0syug
about 49 megabytes

[dieter]

It only works when you add a force that is independent from "the world". This means, it may not be fixed/based on the stator, but on the rotor.
The Water Motor (see left frame) is an example for something like that. Moisture is deforming some stripes on the rotors outline, causing them to bend towards
the center. This makes it a gravity imballance wheel. The bending stripes haven't got any physical or magnetical contact to
the stator, that's why it works. They don't have to push themselfs away from something, but simply deform by their own "power" (whereever that comes from).
But this is just an example.

Simple magnets may be the wrong choice, since the act like any physical contact from stator to rotor - you could even push the wheel with your finger instead.

[mapsrg]

I think that a gravity wheel will work but not with sliding weights.Consider a large number of weights mounted on a wheel with all the weights on the right side of the centre of rotation further away from this centre and all the weights on the left side closer to the centre of rotation.....rotation occurs in a clockwise direction.Since all that is needed to maintain this state is the continuous movement of only two weights(at 12 and 6 oclock positions) which is but a small fraction of the total number involved it must be possible to maintain this unbalanced state......

[infringer]

Turbines are wind asisted or water asisted gravity wheels using the forces of nature including gravity to produce power ... I think the key is to make exsisting devices more easily produceable for manufacturing and useable for the end user aka saving time and money all around.