The Merseburg wheel and the Weissenstein or Kassel wheel were two-way ones and could both be turned in either direction with a gentle push in the desired direction. I have always believed that the way this was achieved was by placing a pair of one-way wheels on the same axle, but with one wheel designed to turn in the opposite direction to its twin. This would create a balanced wheel, with no restrained impulse to turn it in any direction.
Giving it a push sufficient for one weight to fall would initiate the impulse to begin to turn in that direction. Once begun, the sequence would be repeated continuously. When a twinned wheel was to be turned in reverse it had to be designed with one of two options; firstly it could be allowed to move as dictated by the positions the rotation caused it to adopt, with little or no negative effect on the mechanical advantage being generated by it’s paired wheel; or there was a feature or device designed within each mechanism which locked it into whatever position it was in as soon the first weight in the other half of the twinned wheel fell..
Many years ago I tested this theory using models of two Savonius windmills mounted on one axle, but not fixed to the axle. Each one was designed to turn in the opposite direction to its twin. Firstly they were allowed to turn independently of each other and when placed in the path of a fan, each began to rotate in opposite directions. Next I coupled the two windmills together. Now neither moved when in the path of the wind. I gave the joined windmills a little nudge in one direction and the assembly began to turn in one direction. The same thing happened in the other direction of rotation. I gave a full account of the above experiment in my biography of Bessler, “Perpetual Motion; An Ancient Mystery Solved?”
The resultant rotation was about half the speed of the uncoupled windmills. In this example the concave portion of the Savonius windmill when moving against the wind led to a braking effect, hence the slower speed of rotation. However in the Kassel wheel the half speed of rotation was a desired effect to reduce wear on the bearings. In the Merseburg wheel I think Bessler found a way to lock and block negative action in the wheel which was forced to reverse.
If the reversing mirror-imaged wheel generated some resistance to the forward motion of its twin, Bessler must have found a way to wipe out all of it in the Merseburg wheel, because it was able to rotate at about the same speed as the other one-way wheels. Or it might have been possible to stop all mechanical action in the reversing wheel, because without any weight movement there, the wheel would not be out of balance at anytime. Unless the mechanisms stopped in one position which would have led to an imbalance at one point in rotation. It might have been this that Bessler said, gave him a headache trying to set it correctly - stopping the weights from moving at all in the reversing wheel was one task but how to achieve that neutral point of balance at any point in rotation, automatically?
JC