Quote:
Originally Posted by ThaddeusMaximus
Interfacing aside, you need a larger gearbox; the reduction needed for significant force is higher. (Holding torque constant, force decreases with wheel size)
By going to a larger wheel, you:
1. Probably lift your CG up (gearboxes are higher up as well as framing), decreasing stability
2. Shorten the contact patch of the bot (your area of contact is now 14.5" less than the length of your bot instead of only 8"), decreasing stability. Now your contact area is around only 15" (assuming squarebot). I made an offseason bot with this C-C distance once with 10.75 reduction from a single CIM onto 6" wheels, and had enormous issues with being spurred into a wheelie.
3. Force yourself to get rid of a center wheel, so you can't run a drop and decrease turning scrub in this fashion.
All of this would deter me from running these wheels
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You don't
need different gearboxes, but you might want them. We run the old kit drive train in our off-season and t-shirt toy that looks like Dozer with 10 wheelchair tires. (
Interface and
finished product)
You don't have to worry about CG because those things weigh a ton and will keep you planted just fine.
The end result is a machine that, with enough runway, can go really fast. Scary fast indoors, on a football field it's not so bad. We also run ours off a deep cycle marine battery.
My biggest concern would be weight, those things are heavy, and the drive to hold them together is heavy, and the chain to move them is heavy. We build a 6wd with 10 rubber tires and had to ditch it. The drive base weighed in over 70 lbs without a single manipulator on it.
Turning scrub would also be an issue to worry about.