Yes we can agree, as i thought we were saying the same thing in different ways.
I'm definitely convinced of the need for a speed diference, but not too sure that faster is a must.I agree on the different speed, the internal system must therefore be faster than the outer wheel, because it is the driver.
I have built a couple of wheels in the past which had the weights rotating slower than the wheel and they were not successfull. The first was a failure because of the quality of the build, (a crappy prototype to see what was going on) the second was a perfectioned version which worked as desired but no net gain, and no hope of getting one.
The weights were fixed to the central axle on independant arms which interconnected between each other. More correctly, they interconnect with their neighbours, who interconnected with their's. As with the Buzzsaw, the weights could not "pass" each other.
I did modify the second wheel to rotate in the opposite direction, which allowed the weights to fall faster than the wheel, this didn't increase my enthousiasme. I had already, more or less, convinced myself that weights hanging from the center is not the answer, so i wasn't very motivated.
I haven't yet been able to build anything to see if only swinging backward or only swinging forward is favourable. Only swinging backward is achieved with long arms that extend below the center and only swinging forward with short arms that pass over the center. this is where a third system "may" make the difference.It is true that we need the swing, but not backwards and forwards, only forwards.
Therefore I tried to block the reswing with my blocking device.
But that type of movement is hard to control.
So the free swing of the masses is limitated, they can only roll,swing,move in one direction.
1 the wheel
2 the swinging, one way or the other, weights
3 the main weights moved by the swinging weights to create the moving COM.
I wouldn't be surprised to learn that both would work.
I think the energy is coming from movement, so the wheel is not in need of being preloaded.If you have managed then to limitate the movement, then you need the start energy.
The start energy you will get when you set the internal system under stress from gravity.
So we have then a preloaded internal system.
The preload is also essential.
The unidirectional wheel, i think, was configured so as the swinging weights were unable to swing freely and find there natural balance, kind of the one way swinging with no going back, which would not allow the wheel to find balance, even when stopped. The biderectional wheel, worked with the same principal, only without the no return device for each weight. Once the wheel is stopped the individuel weights were able to swing back naturally and find equilibrium.
For me the bidirectional wheel is not under stress from gravity when stationary, if my understanding of what you mean by being under stress is correct.
RH