Swerve drive questions

[Zmarken]

Hello!

Over the summer, and pretty much since the offseason began, I've been looking at various swerve drives created by different teams, trying to figure out how it all works. Unfortunately, I'm a bit stumped.

I've been looking at 1640's swerve, as the documentation on their wiki is wonderful. The first question I have is about the thrust bearings: I get the general idea that they're used to support a load in the direction of the shaft, but I don't understand what they do in their swerve drive. Do they help to turn the axles when there's an axial load being beared, or is it something else completely? Also, when looking at the documentation for assembly (http://wiki.team1640.com/images/4/49/Pivot_Asm_6c.pdf) I noticed on page 8 that on the transfer shaft, it doesn't seem that anything is actually attached by a key or anything. Is that by design, (and does the thrust bearing come into place then?) and if so, then does the transfer shaft just turn because of the friction between the miter gear and the shaft, or am I missing something?

Those are the questions I have right now, and the reason why I'm wondering so much about the thrust bearing is that I haven't really seen that on any of the other swerve drives I've looked at.

Just some questions from a programmer-turned-engineer. I'd like to do swerve drive, if only to have something more challenging, yet doable, for my programmers to work on this year. Any help is appreciated, and thanks in advance!