Interesting idea.........That's sort of a differential gear that's instead of having a single input turn 2 outputs, turn 2 inputs into 1 output?
That's surely possible, but I think requires a lot of precision with the way I design it so the output won't wobble.
I can use 2 similar small sized bevel gears with 1:1 ratio instead of having 1 big bevel gear in the middle, right? If I can make it small enough, then that is pretty good...