pic: Planetary Transmition

[Madison]

Alex,

Can you post a section view of the inside of the planetary so we can have a better look at how you're planning to modify those transmissions to achieve what seems to be coaxial shifting? Most planetary gearboxes used in shifting transmissions on FIRST robots work my sliding the ring gear between stages, but that'd be difficult to accomplish using a coaxial shifting mechanism.

Also, if you're actually getting a ~117:1 reduction in low gear and ~3.5:1 in high-- It's too early for me to do that math -- consider how useful such a large change really will be. What sort of mechanism might require a ~33.5:1 change in ratio in normal operation?

[Alex.Norton]

Thank you very much for all the comments. The reason that I'm using the banebots is because it comes with many of the necessary gears. I'm developing the concept because it is very easy to change the change in reduction by changing the size of the second planetary sun gear. At the moment with a 22 tooth second gear the ratio changes from 1:30 to 1.1:1. If instead I used the gears from the second stage of the banebots (sun being 30 teeth), the reductions would be 2.25:1 and 1:9 which is a much smaller difference in reduction.

Basically this can have a large number on different combinations of reductions without a change in the form factor. Also if anybody wants to check me on those reductions (would definitely be wise) I think that it would actually work better to have the larger gear on the first stage of the planetary. At the moment I believe the directions of the output would depend on the gear your in. So when you changed gears the robot would change direction...

Thanks again for all the coments