Robin
Ok.
You may get away with it then. My understanding is that Polyurethane has excellent wear properties and lousy thermal properties. Hysteresis is the enemy immediately any speed or flexing takes place - both generate internal heat.
Another way of putting it (to my understanding), is that poly is designed to take slide or direct loads of slow velocity/slow cycling. Not the case if you are hacking your vehicle around at 30 or more kph, doing turns and exerting
cyclic forces of many tons
(not vehicle weight, but dynamic force - think of it as force x velocity x time - I am not an engineer, so don't know correct calculation).
Thus if you have a track weighing say 100kg and it is trundling around at 5kph the forces aren't that much. Thrash it around at 30kph and
it becomes an exponential multiplier, you can be talking tons force.
I had an engineer give me a gut estimate of the apparent weight of one of
my Kettenkrad tracks when doing 50kph. He said roughly 1.5 tonne PER TRACK - er, um, that was sobering.
If you are driving your vehicle really slow, say 5 kph maybe 10 kph then this may be the reason you have had no problems. Plus if it is cold (for me, Canada is cold even in summer), would also explain your observations to date as the poly can heat dump sufficiently to stay within its operational parameters. Don't assume that touch test will tell you if things are getting
dicey. The internal temperature can be much higher than the external
temperature of the rubber. The outside can heat dump, the inside can't.
Regards
Doug
Quote:
Originally Posted by Robin Craig
Doug,
We have never had a brand new, made last week road wheel, ever.
I can tell you that the polyurethane wheel we have been trialing has not chipped in the side wall at all and this was the third winter of use.
I will show and report what we experience.
Please bear in mind the cost for us is more calculated in dollar per season than dollar per mile. I would suggest we do on average now less than 300 kilometers a year.
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