Quote:
Originally Posted by lukevanoort
I imagine that is more an effect of the wide wheels wearing down slower than thin wheels; since many tank tracks and wheel treads have a 'cleat-like' pattern, tread wear probably significantly reduces traction. Plus, if the tank treaded robot is running something like Brecoflex Red Linatex (sp?) treads with a CoF of 1.6, I am not suprised that they beat robots running traction wheels with a CoF of 1.3-1.4.
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Actually the custom wrapped rubber wheels never wore down because they did not have a tread pattern in them and the tank treads that we have used are solid with no tread either. So that is not really a problem. In my opnion the tread pattern doesn't really help but I have nothing to substantiate it and this thread is not rellay the place to discuss it. Also I was referring mostly to the surface contact area difference between the differnt wheels and treads not really to the coefficent of friction.
Coefficent of friction is not the end all be all comparisson to tell if someone has more traction it is a factor inthe equation which includes in addition the normal force per square inch and the square inches in contact with the ground. However you do want to maximize the coefficent of friction if you are looking for the best traction you can get.
Sorry if I'm contributing to pulling the thread away from the original intent which is to discuss 294's prototype drive system. I don't really want to do that and I don't really like when it happens.
Back on topic!
I really like the design of the drive sytem, using the pins on the corners really makes a lot of sense.
Another question what bearings are you using on the drive wheels?
I have found that a standard bronze bearing can wear down an aluminum shaft over time. Just something to think about. We had really good luck with rulon and peek bearings which are high perfomance plastic bearings. They work well because they are designed to be compatible with softer shaft materials. The rulon bearings are a reinforced PTFE bearing and I know that you can get them and the peek bearings at mc-master carr.
You could probably save some weight by hollowing out the axles some if you wanted. We have run aluminum tube axles and have great sucess with them. There is minimal shear on them and no unspported length so it hasn't been an issue.