On Wed, 2 Dec 2015, Paul Koning wrote:
I'm sorry for stirring up this hornet's nest.
Well, I put "emoticons" in, in a futile attempt to indicate that I was joking. ("emoticon captioned for the humo[u]r impaired") I also hoped that the "in some states" would give a further hint to that. I couldn't resist the humour opportunity, but I did not intend it to be nasty - it is a reasonable question. And, without feeling hurt, I can always count on y'all to catch me up on inaccuracies! :-)
I actually meant to ask a real question, and the way I phrased it made a mess of things. The real question: for rubber rollers in this sort of application, does the distortion that occurs significantly affect the circumference? Or is the nature of the material such that it's squished out of shape, but circumference does not change much?
The question can remain partially inconclusive. If the rubber is shifting without compression, such as if the ID was too large, then the circumference could be partially unaffected, but then the circumference times the RPM of the axis of the roller is no longer the sole determinant of tape motion.
Compression will have an effect on EFFECTIVE circumference (the amount the tape gets moved, not the actual measurement around the roller) and remains PI times twice the [compressed] radius of the circular segment at the area of contact. Try to IGNORE the other side of the roller that is not compressed, or imagine if the entire roller were equally compressed, not just the contact patch. That's why I included the explicit example where tire pressure change is/was detected by ABS speed sensors (now often done more directly with TPMS)
Here's a similar, but off-topic, one to contemplate: If kids have helium balloons floating against the ceiling of the backseat of your car, which direction do the balloons move when you go around a tight corner?
