Another view of a concept coaxiel swerve module with 3x3 casing and exterior mounted driven and driver sprockets.
All feedback, question, and suggestions are GREATLY appreciated.
Dave,
Nice design…
Looking at the side of this… have we thought of using spur gears at the bottom. The proximity of the two chain sprockets makes me wonder if this might not be possible. What kind of gear ratio COULD we achieve by using spur gears instead of the chain and sprocket.
Just wondering if you had considered this… I am not sure if we can get the gear ratio that we need. this way but they look so close that we should discuss it at least…
Coach
I have some questions & comments:
How does the whole module turn on the vertical axis? Is that a motor with reduction drive in there, or is there something not shown to rotate it?
Is there a way to limit how many turns it can make, so as to not tangle the wires powering the drive motor - or is power to the drive motor* managed differently?
Do you envision the wheel carrier (fork?) as one piece, or made from a few pieces and joined somehow?
What-if you wanted a similar design, but with several inches of ground clearance - like up to the axle for instance - and thoughts on how you might manage that?
Overall, I very much like the design and an considering building something like that as a prototype, but with the intent of using the drive outdoors.
Don,
This is a coaxial drive, so by that I mean that the wheel is turned by rotating the inner shaft of the CO-Axel. It is turned/pointed/aimed by a sprocket that is not shown as it is part of another assembly in my design. Because there is no motor mounted inside the module there is no need to manage turn limits, it can turn around as many times as the driver would like it to and no wires will ever be tangled.
The fork is not really a fork, it is made from 3"x3" (1/4" Wall) aluminum extrusion with a piece of aluminum plate welded to the top to form a prism with one open end.
If you wanted to make an outdoor friendly design I might already have a version that features a 6" wheel that I could email you if you like 
It should give you the ground clearance I think you want. I could also email you a short video that shows how the CO-Axel turns the wheel in this design.
Hope that helps? I would be happy to try and answer again if not…
OK, I get it - the ‘thin’ blue shaft is what spins the wheel for tractive force, while the outer ‘grey’ sleeve rotates within the oragne bushings to steer the wheel. Hm, that’s new to me, but I guess it’s not that uncommon.
Assuming I have it right now, I guess the 90 degree bend is with a pair of bevel gears?
Ok, thinking out loud now: What if the wheel carrier (fork) was offset partway down, so that the vertical rotating shaft terminated at the bottom next to the wheel axle, and the shaft and axle were coupled by bevel gears. (Is that clear enough? Maybe not).
This would allow the wheel to turn about the vertical shaft with a rolling motion on the ground, instead of a scrubbing motion. The advantage here is that it wouldn’t tear up the grass if the wheel turned direction while not moving (driving).
I’d be interested in a JPG of the 6" design you mentioned. I don’t have Inventor (any more), so an image will have to do. I’ll PM my e-mail address. Thanks!