They call it “Paradise.” Then, in the next breath, they call it “The Gateway to Hell.” How else would you describe Pahrump, NV? The city of Pahrump, pop. 33,000, can warm up to well over 100 degrees on a summer afternoon, and it borders California’s Death Valley National Monument, the final resting place of many an overheated vehicle. And yet, on the sunny, 55 degree February morning I visited the offices of Pahrump Valley Fire & Rescue, it sure felt like paradise.
Extremes typify Pahrump, and make the care and maintenance of the fire & rescue fleet a daily challenge for fleet manager John O’Brien.
“We can see a diurnal temperature change of 90 degrees in a day,” he says. “The coldest we get is -10 to -15 below, and our highest temperature recorded was 125 degrees.”
HOT & HEAVY
O’Brien oversees spec’ing and maintenance of a fleet of 45 vehicles stationed at four locations in the Pahrump Valley. The coverage area goes from 312 ft. below sea level all the way up to 8000 ft. above, and, yes, it includes the vast, barren expanses of hell, otherwise known as Death Valley. “Resources are spread thin,” he says. “It could take us up to three or four hours to respond to a call. We get calls up in the mountains that can take us two hours to locate”
The service handles approximately 8,000 emergency calls a year, and tallies up over a million miles annually. And there’s no excuse if a truck has a heat-related failure.
“There are months during the summertime, with the extreme heat, when I may have two, three of four ambulances down in one day,” O’Brien says. “You’re scrambling to put pieces back into your fleet, because you’ve still got to take your calls and provide the same level of service and coverage, but you don’t have the vehicles.
And it’s not just the heat. Although most of the city’s roads have been paved or coated for the past ten years, much of the service area can only be traversed on dusty dirt roads. “We still have a lot of issues with dust,” O’Brien says. “Dust is a big issue on our serpentines, our belt tensioners, because of the high silicon content. We’re seeing a lot of wear issues.”
The heat affects trucks in a lot of ways, but the brakes can be the first to suffer. O’Brien recalls a pair of custom-built trucks that were coming in for brake jobs every 2,000 miles. That’s bad enough from a maintenance standpoint, but the safety factor was even more alarming:
“One day one of the guys was headed to an accident in one of these vehicles, and he goes to take the corner, and he can’t stop,” O’Brien recalls. “He had overheated the brakes making brake applications up to that point,” and that was the end of his call.
“Again, you have to remember the temperature on the pavement: we could be at 165 degrees coming up from the pavement in radiant heat,” he explains. “You add that to the brakes, you add that to the tire, you add that to the powertrain and you’re cooking everything, and it doesn’t have a chance to cool off.”
O’Brien’s solution was to have retarders installed on his bigger trucks. “That’s the only way we stop these big vehicles, because after so many brake applications we start to see brake fade.
“We’ve looked at everything clear down to the foundation of our brakes,” he says. “We looked at the capacity. We looked at S-cams. We looked at the length of throw. We looked at the entire system.
“When we compare a six-inch slack adjuster to a six-and-a-half, we’re increasing the amount of brake pressure with the six-and-a-half, because we’ve got more leverage,” he says. “We also have to look at surface area and surface cooling. We have to look at venting. We’ve even looked at hardening with liquid nitrogen, and we actually get better life on our rotors when we harden them. We need to be creative, and we need to look at all the possibilities.
Since they come standard with all light-duty vehicles anyway, your fleet might as well start reaping the benefits.
Don’t get stuck out in the cold
Air-ride suspension maintenance, part II