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Originally Posted by M. Krass
That is a concern I share. The easiest solution seems to be avoiding shifting while the chain is moving.
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Joe caught on to the same concern that I have, the potential for binding between the carrier gears/sprockets and the chain while shifting. Just based on an eyeball estimation when looking at your illustration, it looks like two sprockets will be in contact with the chain through at least 60 degrees of arc as you rotate the carrier. Given that the C-to-C distance between the sprockets is fixed by the carrier, the chord length between the interfaces of the sprockets and chains will remain constant. If the chain is not moving, then the sprockets must rotate as the carrier moves them through their arcs (and effectively moves them along the chain). Since the chord length is constant, they must rotate at the same rate. If I am interpreting the illustration correctly, the sprockets are fixed on their respective shafts, along with the associated gears on each shaft. Each shaft will attempt to rotate at the rate of the sprockets. But since the gears are also fixed on the shafts, and of different ratios, the shafts will need to rotate at 1/3, 3x or 9x relative to each other (based on the pair in contact with the chain). Since they can't do both, they will lock up and cause the carrier to bind. If the carrier were only moving through a very small arc (<3-4 degrees), you might be able to rely on slop in the system and available backlash to deal with this. But through 60+ degrees of arc, I think there is going to be a problem.
This is a very creative idea, and you are taking things in an innovative direction. But I can't see how the carrier can rotate without binding (whether the chain is moving or not). Am I missing something?
If you can figure out how to resolve this, I do have a suggestion regarding regulating the motion of the carrier. Rather than using a motor to rotate the carrier (and using up one of the available motors, one of your stated "disadvantages"), you could attach a very simple ratchet and pawl mechanism to the carrier, and have the carrier rotated by extension/retraction of a pneumatic piston that reacts against the "arms" of the carrier. It would limit the transmission to shifting in a 3:1/1:1/1:3 pattern, but based on the needs of the game or robot design, that might be OK.
Keep going with this - it is a cool idea!
-dave
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Vmax = 10 ft/sec
Yes, there are two paths you can go by
But in the long run
There's still time to change the road you're on.