I don't think a chilled rail would work well at all. The trouble is that polyurethane is a terrible conductor of heat to begin with, which is why the motion of the tire causes heat to build up inside the tire, and in fact can cause the inside of the tire to actually melt. Which isn't a bad thing by itself so long as the melted stuff can't get out of the wheel. When it does, the wheel is done for rather quickly. As Jeff points out, the wheel will sit for a while in one spot, which means differential cooling on the plastic tire, and I would think that could actually promote premature wheel failure, again, because the tire itself is such a lousy conductor. The wheels, though, being aluminum, are excellent conductors of heat, so if you can get the heat out of the wheel, it will tend to (inefficiently, but it will do it) pull the heat from the tire. Also, is it my imagination, or do these large wheels seem to have thinner than usual tires on them? Again, that would tend to promote the heat to transfer to the metal wheel.
Is it Millennium Force that has little water jets spraying on the wheels in the station? Would be interesting if it is, as that's also the one where I've seen them heating the wheels with propane torches on cold mornings.
--Dave Althoff, Jr.
/X\ _ *** Respect rides. They do not respect you. ***
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Can’t speak for anything more recent, but Millennium had sprayers in the station when I worked there in 2010. On really hot days when the train would pull into the station, the water would immediately turn to steam when hitting the wheels. Created sort of a neat unintended special effect of sorts seeing the train steam from underneath as it pulled in and came to a stop.
I have seen sprayers on in Millennium Force's station, but not very frequently. I have seen them off far more often than I have seen them on, so I have no idea what criteria they use to determine when the wheels need cooling and when they don't. Spraying the wheels with water seems like it may be the most cost effective way of cooling off the wheels.
It makes sense; water has a really high heat capacity, so it is the combination of being a great conductor of heat (so it can easily transfer the heat from the wheels), having high heat capacity (to absorb lots of heat), and being inexpensive, simple, and generally non-toxic that makes it a great choice for that application. It's also a decent lubricant, as Top Thrill Dragster's launch track could attest.
--Dave Althoff, Jr.
/X\ _ *** Respect rides. They do not respect you. ***
/XXX\ /X\ /X\_ _ /X\__ _ _ _____
/XXXXX\ /XXX\ /XXXX\_ /X\ /XXXXX\ /X\ /X\ /XXXXX
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Tony's reaction when the reverse launch hits is priceless. I have a distinct feeling that back-row-top-of-reverse-spike is going to be my new favorite place on a coaster. Feeling weightless at that height staring straight down is going to be pretty epic.
Promoter of fog.
You beat me to it.
Man, I've got a real psychological barrier around the lack of stopper on that reverse tower.
Jeff - Editor - CoasterBuzz.com - My Blog
My guess is that the system is physically incapable of imparting enough power (in the form of kinetic energy) to the train to get it to clear the track. And, if that's true, why spend the money on a mechanical fail-safe?
The counter-argument is: Why spend the money on building the back spike (and tower!) taller than it needs to be? My guess: It's cool to have a balanced silhouette on the skyline.
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