[Steve_Alaniz]

We wanted a crab drive this year and due to weight constraints we just used front crabdrive, which worked very well once we got the rear wheel programming worked out.
The slip ring idea is very cool but a bit exotic. We built longer shafts for our cims with banebot 16:1 transmissions and mounted our motors directly on top of the drive. The motors do not turn (other than the shafts) so no wire twisting. We only built our shafts because Banebot was out of their longer shafts and we had the ability, so that worked out for us. We made everything modular so we could switch a drive in under 5 minutes.
To be honest, the "go to team" on crab drives is 118, the robonauts, and they are really happy to share what they know and how they do it. Their system allows them to use 1 to 4 cims and depending on the game they change the number every year. They had a display at the championship of their many evolutions ( very interesting stuff ). I'd look them up and drop them an e-mail.
The ONE and only drawback is that it is a bit complicated, as you would expect. They only lost the Houston regional last year (2008) because a drive failed at the last match of the finals and they couldn't replace it in time. (the reason we made our drive modular.)
Their mentor, Lucien, is a really great guy so if you really are interested, he's always willing to help out.
Ours is an "economy" drive but if you're interested in our ideas I'll be happy to post the system... I just need to get back to the robot... AFTER I crash for awhile... (it's been a LONG season!)

Good Luck!

Steve