DT....pg. 244....J. Collins..."It then began to rotate of its own accord with such force that within a minute it had rotated 40 and more times, and could only be stopped by applying great effort."
Mersburg
I wish to show you two different examples, one of a mass dropping at constant acceleration of gravity for the height of one minute rotation of the Mersburg wheel from start, also from of the height of the wheel into constant velocity from just the wheel height then compare them to the velocity of the Mersburg wheel after 60 sec.
3rd wheel,133.8" diameter @ 40 RPM, at Mersburg was 7.12 m/sec (a point on the rim), max theoretical is 8.17 m/s (at gravitational 9.81m/s^2 from 3.398m)
A mass dropped the vertical distance of the circumference of the Mersburg wheel 133.8 inch = 3.398 52 meter,
v = 2( 9.81 m/s^2 x 3.99 m) = 8.17m/s T= 2h/g = 2 x 3.398m / 9.81m/s^2 = .83sec
A point on the wheel has traveled 40 rotations x 3.398m = 135.92m
So a mass dropped at that vertical distance T = 2h/g = 2 x 135.92m / 9.81m/s^2 = 5.26 sec... which is well under the 60 sec for the same distance for the wheel.
Theoretical gravity drop for 60 sec would be h=1/2gt^2 = 1/2 x 9.81m/s^2 x 60 sec x 60 sec = 17658m
Rotations the Mersburg wheel would have done if in constant vertical freefall in 1 minute 17658m / 3.398m = 5196 times
v=2gh = 2 x 9.81m/s^2 x 17658m = 588.6m/s
It sounds like a quick start 40 rpm in the first minute, but is well within the range of a gravity only operated device if one side of the wheel always feels it is falling (remember weight of the mass does not matter just the fact some of it feels it is) or every single mass had to start and stop once ( it did not have continual freefall). The fact alone that the wheel was doing a velocity of 7.12m/sec and the theoretical velocity of a mass from the wheel hieght 3.398m at 9.81 m/s^ 2 is 8.17 m/s which is still under the theoretical max value. So in conclusion there might not need to be secondary driver or energy input, the numbers are still within gravity assisted only range and the wheel would have to be at this fast initial velocity if you expected to get any work out of it. Of course this does not excluded extra energy added in, only that it was not going faster the acceleration or velocity of gravity over the height of the wheel or height in rim travel.
40 plus rpm is defiantly fast though and add in the 8 weight thuds per rotation and suddenly you listening to 320 smacks per minute... no wonder there was conflicting reports as to rpm and weight thuds. The Gera wheel going at 70 rpm would have been 560 whacks and sounded like just a lot of clatter, imagine yourself trying to count those. Thinking about it...Its enough to make your head spin and say the wheel was spring driven ;)))