[asid61]

Originally Posted by Chris is me

From the title at first I thought this was an ABS gearbox and I was concerned. Looks good though! Generic comment about supporting your CIMs marginally better goes here.

Interesting that you noted that. All of my other gearboxes have a better cim support, but I elected to forgo it in this case due to the lack of demonstrated need for one. A couple of my old gearboxes which were actually manufactured did not have cim supports and functioned ok, and I figure that will hold true for this as well.

Originally Posted by JesseK

This latest round of gearboxes seems to be missing a very critical (IMO) component for the implied WCD setup they're for: the outer bearing block for the direct-drive wheel. Would adding that bearing block (such as the WCP one) cause issues? It simply requires adding two extra threaded holes around the existing output bearing hole.

I was planning on not using a bearing block on this one and instead directly pressing bearings into the 2x1 and using a double sprocket, however I will add mounting holes for the WCP bearing block just in case. Thanks for the idea!

Originally Posted by Joey Milia

I had a look at your ball shifting shaft and the shaft itself looks fine. I found it interesting that you made the shaft wall 1/8 thick so the balls can't fully engage, that might be a problem with wear depending on gear material and tolerances but it could very well be totally fine.

What I am very concerned about is bearing load. Its seems you're using R1212 bearings and according to lily bearings (http://www.lily-bearing.com/ballbear...12-bearing.htm) they only have a dynamic load rating of 111 newtons and static rating even lower. These numbers may be very conservative (or just wrong) but I would recommend doing some math and researching the ratings of the actual bearings you'd use to see if they'd work. If not, look into bushings or bigger/different bearings.

I am using Boca SR1212-ZZ, which has a stated dynamic load of 94kg (207lb). I figured that would be enough for these, but I can swap them for bushings relatively easily if needed; that would also remove/reduce the need for spacer shims.
Thanks for pointing that out.
The balls should be able to fully engage with the grooves in the gears. I made sure that the balls wouldn't be able to "get stuck" in the grooves, but not so much that it wouldn't engage. What do you mean?

Originally Posted by Nathan Streeter

I've never designed a PTO gearbox, but this one inspired me to think about it more... as I was thinking about it more, I couldn't come up with how a gearbox with a single shifter shaft / output shaft could be used to get a PTO... After having thought about it a bit more, it seems to me that it requires having 2 shifter shafts OR having the shifting shaft not be the output shaft.

Nailed it! That was my thinking exactly; I've struggled with this problem in the past.