Here’s a gearbox I designed using vex/wcp parts. Including a 22-32 chain reduction and 4 inch wheels, it is geared for approximately 17 ft/s theoretically, in aim of around 15-16 ft/s. Low gear is as low as possible given the high gear ratio. with motors and all hardware, it only weighs 11 pounds, almost 2 pounds lighter than a WCP 3 CIM DS and only 2 pounds heavier than an AM 2 CIM Super Shifter. The motors are also all located at the furthest possible lowest point, the best one in terms of CG. The final design point is it’s height, it is only 4 5/8 inches tall allowing a relatively short sheet metal chassis to contain it.
This was my first custom gearbox design, so there might be issues with it, please don’t hesitate to point them out.
The CAD files, both Inventor and STEP are located at: https://drive.google.com/folderview?id=0B0soKk9hjXfLYXlQSU1KMXBKbkE&usp=drive_web