This was 4087’s off-season CAD exercise for our students. This flipped 2 speed transmission tries to utilize as many COTS components as possible.
Files are available here:
This was 4087’s off-season CAD exercise for our students. This flipped 2 speed transmission tries to utilize as many COTS components as possible.
I have to admit, I think this is the first “flipped” gearbox I’ve seen that I actually liked, and one of the few that doesn’t appear to take up more space than the original “unflipped” version.
Does this use standard VexPro Ball shifter ratios, and if so, is it the 2CIM or 3CIM ball shifter ratios?
Also, what’s the purpose of the spacers on the 3rd stage gears? Looks like they could be trimmed down and you could shorten the assembly by a few tenths of an inch to me.
Any reason you have the nuts to the mounting bolts on the inside of the tube? Seems like it’d be a lot easier to flip those.
Very very nice. I love the way you’ve arranged your gears here to minimize thickness. I would tap the plate or put nuts on the gearbox end however. Thank you for releasing the CAD!
What gear ratios are you running?
Thanks for your comments and compliments! Another mentor and our kiddos were the chief designers behind this; my contribution was minimal.
However, I think i can address some of the design questions posed. This gearbox is intended to interface with the AMU14u3 with minimal cutting and drilling. The gearbox could most definitely be slimmed down further by modifying some of the COTS components, but we have limited lathe access. Our intent is for this to be a stepping stone to a fully custom chassis as our resources grow.
Sent from my iPhone using Tapatalk
This is designed around Vexpro gears, including the COTS short shaft ball shifter mechanism. The only parts we have to fab are the two bearing plates and the lathing of the two axles. The team has access to Maker spaces at Tulane University and at the Chevron-sponsored Fab Lab at the local community college.
Gear ratios are 4.6 and 18.8. It’s designed for 4 inch wheels, but we can swap gears for 6 or 8 inch wheels. In high gear, it has a speed of 14 FPS at 30 amps and in low gear has a push force of 146 lbf at 30 amps, just below the wheel friction limit.
The gearbox attaches directly to the inside rail of the KoP chassis via the standoffs, replacing the std AM Toughbox.
There is a little room to narrow the assembly - maybe 0.063 inches. But any more would have the motors hang over the edge of the outside chassis rail.
Sent from my iPhone using Tapatalk
No particular reason. Could be oriented in opposite direction.
Sent from my iPad using Tapatalk
I’m not a big fan of tapping aluminum in situations where you need to frequently disassemble and reassemble. Can certainly be done, if you dare.
See my response above regarding your question on gear ratio
Sent from my iPad using Tapatalk