How do you prevent the balls from moving radially outward when the shaft is spinning? I would think that the centrifugal force on them from the spinning shaft would tend to push them out into the slots in the gears.
I (and from reading this thread, many others also) would be very interested in seeing a photo or drawing of how your sliding rod works to move the balls in and out. I would also be interested in knowing how you cut the slots in the gears.
If you put a sensor on both shafts, I think you could make a really slick automatic transmission with this gearbox.
When the software figures it's time to shift up to the next higher gear, indicated by high motor speed, the control computer would put the gearbox in neutral, then drop the motor speed down so that the input shaft speed, as measured by the period between sensor input triggers on the input shaft, matches the period measured on the output shaft, adjusted for the gear ratio of the next desired gear. At this motor speed the desired input/output gears are spinning at exactly the same speed. Then the contoller would shift to the desired gear, the balls pop into place on the output gear, and the controller applies power to the motor, accelerating away in the higher gear. A similar sequence can be used to down-shift, where the motor speed is increased while in neutral to match gear speeds. The system would work like a sensor-controlled synchromesh. (I would call is "automatic sensor synchromesh" if not for the unfortunate acronym
. Maybe "sensor controlled synchro - SCS would be a better term.)
In any case, this would be a neat project to work on. Any chance of getting some more details?