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Unread 09-05-2013, 13:25
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thefro526 thefro526 is offline
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Re: Highest traction wheels

Quote:
Originally Posted by smistthegreat View Post
I've heard good things about cutting tread into Colsons like so: http://www.team228.org/gallery/125/b...3511-8f172.jpg

I have no concrete evidence that this increases traction, but I know 228, 125, and I think 1477 all cut their tread like this so perhaps someone from one of those teams can chime in here with some data.

In response to Pat's questions about extremely small traction wheels, the only COTS ones I can think of are Colsons and Banebots, and even the hardest (blue) Banebots wheels would have to be changed too often to be worth it. I would at least explore the possibility of cutting treads into Colsons, because the alternatives are machining intensive.
IIRC, I've heard numbers of 1.4-1.5 COF being thrown around when talking about Colsons with treads cut into them. Don't quote me on that, as I'm not 100% sure, but I will try to confirm when I get a chance.

Quote:
Originally Posted by JamesCH95 View Post
Physics teachers the world over repeat this simplification. It is not true in real life. Coefficient of friction is a function of contact pressure for every traction system I've seen, namely coefficient of friction increases as contact pressure decreases.

(really awesome stuff removed to keep post length reasonable)

This is the theory I've learned and experienced with race car design/driving and some FRC teams have demonstrated through testing robot wheels.
This, all of this.

One thing that I'd like to add, is there's also a 'cleat-ing' effect (mechanical interaction) between some wheels and carpeted surface. Roughtop Tread (any form, though harder is better) and the 'W' tread on versawheels are both good examples of materials where this comes into play.

Think of something like a plastic carpet runner, the kind with little plastic spikes on one side and a textured surface on the other. If you applied traditional friction models to them, you'd see that the math just doesn't add up. (or shouldn't add up) If you dig into this a bit more, you'll start to see that the spikes dig into the carpet and make it seem like there's more friction between the two surfaces than there really is.
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