[JamesCH95]

Originally Posted by Gary Dillard

While that may be true for "frictional traction", it's not necessarily true on carpet where a considerable amount of the tractive force is actually a normal force between projections on the wheels and fibers on the carpet. The reason brekoflex type belting and some mechanums get such good traction is the amount of embedded overlap when edges on the wheel surface dig down into the carpet, which is a function of weight but more importantly an inverse function of contact area. Our previous testing and data has shown this.

Some teams have run experiments showing that wider wheels, i.e. ones with more ground contact, get better grip. A big part of this is that the 'embedded overlap' interface you talk about becomes saturated at a certain contact pressure (the carpet and tread have finite depth) and as pressure increases above this threshold the coefficient of friction drops off. Even before the interface is totally saturated the coefficient of friction generally drops off slightly with load because the carpet/tread presses together more firmly, making it more difficult for the tread to embed further.

This analysis is based on my knowledge of tire-road interfaces and what I've learned from reading many CD threads on the subject.

One thread with related discussion is here: http://www.chiefdelphi.com/forums/sh...ad.php?t=98664