254 Gearbox Analysis

[craigboez]

Always great innovators, the Cheesy Poofs did not disappoint last year. Their 2010 effort was an outstanding one, and I've decided to put togther a case study and present it to my team in preparation for the upcoming season. In doing I realized just how great their gearbox was and thought I'd share and also try to collaboratively reverse engineer it.

Basic Overview
http://www.team254.com/media/photos/...e=orig&id=4247

They advertise this as a two speed transmission, running at 5 and 15 fps, which strangely has two shifting cylinders. It was part of an 8-wheel drive robot, with one wheel per side direct drive and three more driven by the pictured sprockets. The truly unique feature is the Power Take Off (PTO) that they used to power their lift mechanism. Under normal operation the gearboxes would power the drivetrain. Under PTO mode those motors were repurposed for lifting the robot. Very successfully I might add. Check out the end of this clip:
http://www.thebluealliance.net/tbatv/match/2010sj_f1m1

I wasn't able to uncover any great pics of the PTO mechanism, but this side view clearly shows a pneumatic cylinder that would appear to be the toggle mechanism.
http://www.team254.com/media/photos/...e=orig&id=3139
EDIT: This appears to be a false assumption

You can see an upper sprocket in this pic, a top view. This is presumably used to drive a chain that powered their lifter. There does not appear to be a dog gear so I'm unsure how they so reliably transferred power from one output shaft to another. Anybody know?
http://www.team254.com/media/photos/...e=orig&id=4249

Also, what is this clutch for? It looks like a small slip clutch, maybe used to limit torque?
EDIT: This is a different gearbox from the pictures above. This was used to power the roller/ball collector mechanism.
http://www.team254.com/media/photos/...e=orig&id=4251