pic: Inverted CIM 2-Speed Gearbox

[asid61]

Originally Posted by KohKohPuffs

I've been punching some numbers into JVN design calculator, and I managed 16.85fps high, and 6.76fps low.

This will be a new design (but I'm keeping the inverted CIMs), since to do this I had to have the dog gears be the driven gears rather than the driving gears in the second stage (shifting on upper shaft). Also, in order to have the gear space in the gearbox, I'm most likely going to keep the idlers:

1. The idler gears are easily replacable in case they wear out
2. Using my logic, the idler gears are made of steel, so I doubt wearing down is going to be significant

As for a belted gearbox, I think our team wants to move away from belts. It's a bit complicated, but even if it is better than idlers, I'd rather work on the current style I have going.

Thoughts?

Those speeds are much better, you should be able to withstand a pushing match for a least a little while (I'm getting about 50A current draw with 4.2" wheels, 150lbs, and 1.3 CoF).
Removing the idlers can only do you good, regardless of wearing out. Reduces complexity and weight. If you have to keep them, that makes sense, but I would remove them if at all possible.
What are you guys moving away from belts for? The epitome of flipped-cim gearboxes (192 in 2014) used belts for their first stage and it reportedly went swimmingly. Saves a lot of weight and space in these things IME.