Shafts in Drivetrains

[Akash Rastogi]

Originally Posted by Andrew Lawrence

As long as the shaft is sufficiently supported, there's absolutely no problem with cantilevering the shafts. It's commonly found on a West Coast Drive, where the axles are live and well supported by a bearing block.

This is an overly simplified statement. Quite a few factors go into shafts for a WCD, including material used (I don't use 6061 to cantilever since friends reported bending of shafts on their bots), stress risers along the shaft, length of the shaft, load at the end of the shaft, etc... These factors are most important for the output shaft of the gearbox.

I haven't seen teams have wheels "fall off," but I have heard of the occasional shaft snapping near a retaining ring groove, and causing issues. You can retain wheels using snap rings, I prefer to tap the end of the shaft in order to drop in a large washer and bolt to hold the wheel on. The retaining rings at the ends of a shaft don't/shouldn't cause problems though.

I only have anecdotal evidence from other teams and from 3929's 2013 drive, but as far as I can tell, cantilevered shafts are A-okay with the proper setup. Check out any 254/968/973/1538/1323/987/60/696 bot as examples.

There's a good amount of discussion on this photo as well - http://www.chiefdelphi.com/media/photos/35912 but deals with a shaft used in a shifting PTO gearbox. I don't think single speed gearboxes have nearly as many issues to worry about.