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Unread 11-14-2017, 10:07 AM
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AriMB AriMB is offline
The Philadelphian emigrant
AKA: Ari Meles-Braverman
FRC #5987 (Galaxia)
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Re: pic: 2-Speed Flipped CIM Gearbox

Quote:
Originally Posted by cad321 View Post
I really like the design of this; it's unfortunate you couldn't keep it down to 2 stages, but in return for the packaging , it all works out. A few questions.

One, what size wheel is this designed to be run with?

Two, is that gear ratio adjusted or free speed.

And finally, why a dog shifter over ball shifter (note i'd be asking the other way around if you had chosen ball shifter, just curious)?
It's designed to use a 4" wheel. That is the adjusted gear ratio, though I'm not so set on that final ratio. It's super easy to change the final ratio by changing the 3rd gear set. Dog shifter because it packaged better in this application (all 3 gears between the bearings instead of just the shifter gears between and the third cantilevered).

Quote:
Originally Posted by cbale2000 View Post
Without seeing this on a chassis with bumpers it's really hard to tell, but my initial concern is how far that cylinder protrudes past the wheel.

I feel like a better option would be to connect the cylinder using some sort of armature and mounting the cylinder inside the gearbox, pushing out. Alternatively, it also looks like you could also reverse some of the gear orientations and mount the cylinder on the inside of the frame.

True you would protrude into the frame area more with the later of those two options, but it looks like in the current configuration your bumpers would have to extend out to protect the cylinder anyways, so you'd either have a large wasted space past the wheels or a small wasted space inside the frame.
According to the CAD model, the back of the pancake cylinder is ~0.03" inside of the end of the colson retaining screw, so the bumpers shouldn't need to move out substantially. To achieve that, I had to substitute the spacers that come with the hardware kit with custom spacers, and use a custom shifting shaft. I know it's still close, but the bumper should help protect it, and I really wanted to keep the cylinder on the outside for space reasons (that was kind of the main requirement for designing this).
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Studying MechE at the Technion - Israel Institute of Technology
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2012-2016: Member FRC 423 Captian, Programmer (LabVIEW), Electrical, CAD, Manipulator, Chassis, Business, Outreach (everything)
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