Imagine if you can, the chassis of a 20,000 lb. bus or large RV being strapped to a dynomometer for a performance test. This is exactly what one of our customers does albeit on an infrequent basis, but often enough that they have to be concerned about an overheating condition that appears in the tires. The tires are running over the same surface on the dyno drum and the thousands of interactions of the tread slipping over the drum cause friction and heat. In time the tires overheat and can fail.

In the past, the customer has “shaved” the treads off the tires they use, but that is time-consuming and problematic to say the least. The customer could also look into investing in a newer dyno with through-the-roll cooling, but they are very expensive and for the rate of use, not a viable option for this company.

So, cooling the surfaces that generate the heat is the next option and that is where EXAIR comes into play. Since all the chassis are of a dual, rear wheel configuration, we have 4 points to cool, 2 per side.

One of the requirements of the cooling system was that it be compact so it could fit in under the chassis on a fixture without interfering with the test. After discussing the options, the customer decided to go with (4) model 5315 Cold gun Systems, to cool the tire/drum interface. The customer tried it and the Cold Guns were able to keep the tires and drum cool.  Even under high load, the temperature only climbed to a little more than warm, which was totally acceptable.

Neal Raker
Application Engineer
nealraker@exair.com