A working ball wheel

[armagdn03]

Hans brilliant assessment, only one little thing that you may have missed. You observed that the center of gravity will fall on a point excentric to the disk. You also noted that in order to have the wheel run true, one would have to compensate. Since there are more than one wheel in the stack, and they are arranged in a geometrically perfect arangement, with equal rotation they should balance each other out when assembled. This problem should take care of itself. However, perhaps it could be exploited?

[AB Hammer]

Hans

I have 1 other question. On your drawings with 12 block sections, there is 6 positive 1 neutral, and 5 negative. Lets add some momentum also note the the neutral balls are still rolling. Wouldn't that have a loping effect when running and just enough to run if it runs?

[hansvonlieven]

G'day all,

@ arma,

What you are saying about the displacement of the centre of gravity and about the forces so created canceling each other out is certainly true if there are no balls in the system and the drum runs empty.

With the balls in play I am not so certain they would. Let us just briefly examine what it is that we are trying to do here. How are we trying to achieve rotation?

Looking at one disk and one ball as a unit and following the movement of the ball during one complete revolution we notice that the distance between the centre of gravity of the ball changes its distance from the axle to return to its starting position after one complete turn. With each change of distance from the axle the centre of gravity of the UNIT gets displaced. In other words we are trying to achieve rotation by manipulation of the centre of gravity.

In the above example the cutout is almost exactly radial. That means that the shift of the centre of gravity is almost exactly in the oppoite direction to the position of the ball. In other words in its optimum position of potential energy it acts as a counterweight. That effect would have to be cumulative over the entire structure.

What further complicates the issue is that the ball does not move in a straight line in relation to the new centre of gravity. That means that the effective potential energy is adversely affected to a different degree for each change of position of the ball.

These effects are impossible to calculate in a general way, they can only be established for a given configuration.

The factors that have to be taken into consideration when assessing the forces at play are the shape of the cavity, the weight of the disk and the weight of the ball the material used in the ball and the disk as this determines the drag imposed by friction on the ball and so forth.

Very complex stuff for such a simple contraption :-) Even a complete mathematical analysis will at best be only an approximation. Real parameters have to be established by experimentation and measurement.

Which brings me to Hammer's question.

Is there enough inertia building up over the "working cycle" to compensate for the adverse cycle? I would say not. There are too many factors adversely affecting the system for it to do that.

Hans von Lieven

[AB Hammer]

Hans
I wish I could talk like you, but it seams that my mind is full of shapes and lacking for words.

To all who follows this thread.

I will go ahead an build the 1st type again in wood, Plexiglas and steel this time, if nothing else but for at least my own peace of mind. But this time I will use disk so I can make it thinner and make an AVI of it, to show.

[hansvonlieven]

You are doing well Hammer,

Keep trying, if you need my input at any time feel free to contact me, privately if you wish.

Good luck

Hans von Lieven