Losing Sleep Over Inflation
Automatic tire inflation systems offer peace of mind
Evan Lockridge
Contributing Editor
Making sure your truck tires are properly inflated isn't always a driver's top priority. Some drivers never check the air, while others still think using a tire billy is the best way to check inflation.
Your rigs might go for weeks, or even months before they're seen by a technician.
Yet poor tire inflation leads to more fuel consumption, rapid tire wear and the potential for roadside emergencies.
Why, it's enough to keep a maintenance manager from ever getting a good night's sleep.
Fortunately, there is solution to this nightmare – automatic tire inflation systems. The devices aren't new, but they are becoming more popular. They also are not to be confused with tire pressure monitors.
"With a tire pressure monitor, you still have to add air to the tire," says Frank Sonzala, president of the tire inflation system manufacturer PSI, whose product is marketed exclusively by ArvinMeritor. "Tire inflation systems not only monitor the tires, but they also inflate them when they have a loss of air pressure." Whether the pressure loss is due to a slow leak or a puncture, the truck continues down the road until the driver can get it fixed.
In addition to saving money on tires and fuel, a tire inflation system maximizes your ability to retread tires. By reducing the chances for a blowout you also reduce instability and damage to the trailer. And if you are running wide-based tires, the need for such a system is even greater, because it's nearly impossible to limp along to the nearest service facility when one tire has gone flat.
Tire inflation systems essentially work by taking excess air pressure from the air brake tank, running it through a control box and transferring it into either the axle or lines running through the axle, and then to lines that lead to the tire valves. They also feature a warning light on the side of the trailer that can be seen from the driver's side view mirror. These alert the driver that tire inflation is under way or that there are more significant problems, depending on the tire inflation system. All are set up so that too much air is never taken away from the brake system, so you don't lose the ability to stop the vehicle.
All of these system are self-contained, and with one exception, all are for use only on the trailer tires. But there are differences between the systems.
The Meritor Automatic Tire Inflation System by PSI continuously supplies a flow of air through the axle tube to the tire and does it immediately. It can maintain continuous pressure in a damaged tire for hundreds of miles if needed. It's preferably ordered on new trailers through the factory, but can be retrofitted.
This summer the company announced improvements to its product. The most significant is the introduction of a heat sensor to warn drivers when heat is building up in the wheel end, allowing fleets to schedule repairs before a possible wheel loss or fire. PSI also unveiled a prototype that will allow the use of its product on tractors, something that is rare in the tire inflation system arena.
The Airgo Automated Tire Inflation System is one of the newest entrants, launched in 2003 by a number of people formerly from PSI. It delivers air very much the same way as the Meritor system, providing continuous pressure through the axle. However, it also can use air lines running through the axles to deliver air so as not to pressurize the axle tube. The Airgo system is available at the OEM and aftermarket levels.
The Dana/Spicer Tire Inflation and Monitoring System and TireMaax from Hendrickson work differently from the Meritor and Airgo systems. These "intermittent," or "variable," systems run in a depressurized state when inflation is not required, using lines running through the axle to deliver air. These systems use an electronic control unit to monitor the tire pressure and decide when to add more air. The ECU also allows the system to illuminate the trailer light only when there is a problem to which a driver needs to be alerted.
TireMaax is available mainly at the OEM level. The Hendrickson system can be retrofitted, but will end up costing much more than if it was originally installed on the trailer.
This month Dana/Spicer plans to release free software through its web site, allowing users to service the product, look at service codes and test the system. It will also allow them to access historical information in terms of what kind of air pressures the system has logged, aiding fleet managers in identifying tires that consistently need air – a possible sign of other tire problems.
Earlier this year, Dana/Spicer announced its tire inflation system can be integrated with the new Bendix TABS-6 antilock braking system for trailers within one electronic control unit. This allows for easier installation of both products, fewer components and wiring, easier service and reduced weight.
Because this system is tied into the ABS power line carrier, tire pressure and system status can be provided in the cab via dashboard displays, as well as to off-board communication systems.
Though not the newest entrant in this field, the Vigia Automatic Tire Pressure System is probably the least well-known. Sold by Safer Corp. for about four years now, Vigia got its start around 30 years ago by manufacturer Col-Ven in Argentina. Today it's found throughout South America, Europe and elsewhere.
It runs in a pressurized state like the PSI or Airgo systems and uses small pipes running through the trailer axles to get air to hoses on the tire valve stems. Vigia also features a light panel that shows the status of the system, which can be mounted on the side of trailer so it's visible from the driver's side mirror, or installed inside the tractor.
The biggest difference is Vigia also has a system for tractors, using what Safer Corp. calls "an external system." "Since we can't go through the axles like the internal system, it's by means of running the piping and having some sort of hinged arm that comes down and attaches to the hub of the wheel," says Brian Moylan, president of Safer Corp.
It's also worth noting the Vigia tractor system can be set up to have different air pressure on each tractor axle. Also there are three gauges inside the cab that shows the air pressure and when air is being added to the tractor tires.
No matter which system you prefer for your operation, all offer about the same return on your investment – between six and 18 months.
Automatic tire inflation systems pay for themselves long after their purchase through better fuel economy, longer tread life and fewer roadside service calls .
And that can certainly can make for pleasant dreams for a fleet manager.
