Wrong PSI? Now What?
Mark Putz
Associate Editor
For fleets seeking electronic tire pressure monitors, today's array of such devices offers something for everyone. Many fleets say they like to keep it simple when it comes to the air in their tires. And by "simple" they mean inexpensive. No argument there.
"But just recording tire pressure without a filling system is a double-edged sword," says Frank Sonzala, executive vice president of P.S.I. "From a liability standpoint, fleets are saying, 'We know our tires aren't properly inflated. We want to do something about it.'"
Since Meritor Tire Inflation Systems (MTIS) by P.S.I is a fully automatic inflation system, fleets don't monitor inflation, they maintain it. Sonzala says MTIS remains the market leader and is shipping in record numbers. "We've crossed over from intermodal fleets to over-the-road fleets and independents."
Nonetheless, the low up-front cost and the simplicity of a "monitor only" system like PressurePro from Doran Manufacturing is the way to go for many smaller operations. PressurePro doesn't supply air to a low tire, but then "when a tire is losing air you're always faced with fixing the problem," says Jim Wahl, of Wahl Marketing Communications.
Another example of a "monitor-only" system is offered by SmartTire (partnered with Haldex). The Tire Pressure Monitoring Systems (TPMS) has a new receiver enabling integration with any commercial vehicle architecture. The TPMS utilizes a sensitive, weatherproof chassis-mounted receiver. The system integrates effectively with in-vehicle displays, and monitors both temperature and tire pressure.
Of course, not all fleets want drivers alerted to a numeric pressure. Many fleets are adamant about keeping drivers "out of the numbers game." In other words, drivers are better off not seeing gauges. They might be tempted to lower pressure to suit their preference. With this in mind, Airgo's constant air-inflation system functions as a tire-pressure monitoring system by keeping tires filled to a preset psi. When a tire loses pressure due to a puncture or other seepage, a warning indicator alerts the driver via a light mounted on the trailer in sight of the driver's rear view mirror. The driver can then assess the problem.
Another system that automatically maintains tire pressure from the trailer's air system is PressureGuard Tire Inflation Systems from Reineke. It likewise monitors pressure and releases compressed air from the tractor's system when tire pressure drops below the preset pressure level. Reineke says it is working hard to fill any information gaps that may arise as far-flung service techs handle routine wheel-end work and tire changes.
This idea of service on the road is always a sticking point with any "new" system on a truck. Operators understandably worry about damage to the system or parts availability. But this is changing as the big players announce plans to begin high-volume production of their systems. For example, Dana says it's gearing up for high-volume production of the Spicer Tire Maintenance System (TMS) in the third quarter of 2004.
Dana says TMS has the advantage of actually measuring pressure instead of just filling the tire to the preset level. This is important because a fleet can set the threshold to include normal pressure changes from heat and cold. Dana says feedback from fleets has been positive. "With our system, you avoid scenarios where you have to tell the driver to ignore a warning light that blinks on under normal psi shifts," said Jim Beverly, chief engineer for Dana's Advanced Chassis Control Systems.
This is a key feature of the system: The indicator lamp only comes on when service is required. This prevents driver confusion when only minor inflation is required. The system warns when tires are 10% low and until correct pressure is achieved.
Likewise,Tiremaax from Hendrickson activates only when needed — constant air pressurization to the tires is not required. The system touts a rugged design that nearly doubles the size of the hubcap tee fitting. An added guard around the tee fitting protects it during tire removal, reducing potential damage. Premium hoses feature braided stainless steel jackets and larger barrels for fitting connectors. Check valves help prevent tire pressure loss back through the system. Drivers can manually fill and check pressure at the hose ends, and a light notifies the operator of the system status.
When and how a system alerts the driver is important. For example, Advantage PressurePro LLC, offers a system with small sensors that screw onto the valve stems and report to a control module via RF. This monitor alerts when tire pressures fall by 12.5%, and again at 25%.
Neal Lynch, chairman of Kelly Oil Co., cites a classic example of the utility of this monitor-only system. "The second trip with the system proved its worth, notifying us of a low tire. The first thought was the system didn't work because we had just checked those tires before leaving. Sure enough, a tire had picked up a screw on the inside passenger dual."
And like most monitor-only systems, PressurePro installs quickly and easily, according to Lynch, "We installed the 10 wheels and it took about 20 minutes."
This ease of installation can extend to air-supply systems as well. The Trailer Rotating Air Chamber System (T-RAC) from Trans Technologies supplies air and monitors pressure while touting a quick install.
We tend to worry about underinflation, but as a tire heats up during normal operation the pressure inside rises. T-RAC's tire manager solves this problem with a relief valve. The system's valves have the ability to release the excess pressure above 120 psi automatically.
As usual, space limitations prevent us mentioning the many available options, for more information visit www.truckinginfo.com.
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