This is a drivetrain we are currently building. It has a custom 3 CIM 2 speed gearbox designed for lots of acceleration with a reasonable top speed. It uses a pneumatic cylinder to shift one of the outside wheels, lifting the robot enough to only be on the shifted wheel and the other outside wheel, any of the wheels can be either traction wheels or omni wheels. We plan on first testing it with omni wheels on the outside and traction on the inside, however we have been warned that we may not be able to push anything in this configuration and have left omnis on the inside and tractions on the outside as an option. Overall, the entire thing only weighs 32 pounds, only slightly more than our 2014 robot’s 4 CIM standard tank drive. The cad is available at http://frcdesigns.com/designs-drive/
This has been strongly influenced by 624’s grasshopper drivetrain as well as other sheet metal robots like 67, 148 and 33, I’d like to thank those teams (and others) for making their CAD and/or help public. I don’t think this could exist without this.
Future improvements and tests: (I already have a list and it isn’t even built…)
I’d like to make the shifting modules out of bent, thin metal like 1114’s omni wheel modules.
Single speed gearbox, I’d like to try to get the shifting gear change by giving the different wheel’s different sprockets, however this may be an issue as the inside and outside wheels may touch the ground at the same time. We’ll try it out on this and possibly include it in a future iteration
Lighter gearbox, I’d like to try using thinner gearbox plates and using flanges for a better strength/weight ratio.
Upside down electrical board, while not in this CAD, the electrical board will be upside down as an experiment.
[*]3d printed encoder mount and spacers
Any other improvements or criticisms?