Tire Inflation Systems
Evan Lockridge
Contributing Editor
Air – and the proper amount of it – is necessary to maintain life. Without it, we die. Tires, while obviously not a living and breathing organism like you and me, also have to have air, and enough of it, to do what they're designed to do: Move vehicles from point A to point B.
The problem is, checking the tire pressure on an 18-wheeler, especially the inside duals, is about as much fun as a poke in the eye. That's one reason why only 45 percent of truck tires are within 5 psi of their target pressure, according to research by the Federal Motor Carrier Safety Administration.
While there are some gadgets designed to make this process easier, they still require manual checks and inflation – unless you use a central tire inflation system.
These systems do all of the work for you. Unlike drivers or technicians, the tire inflation system is always on duty. Simply put, they monitor tire inflation pressure and keep the tires filled to the proper air pressure. There are several reasons this is so important. Even the most properly cared for tire loses a couple of pounds of air pressure each month due to the air molecules seeping through the tire casing and rubber as well as around the bead area. Tires also can pick up road debris that can cause a slow to moderate loss in air pressure.
Low tire pressure reduces fuel economy, causes uneven and premature wear and can damage the casing, rendering it useless when it comes time to retread. Then there are the costs and downtime of a tire running flat in the middle of nowhere in the dead of night.
Tire inflation systems work by taking air from the truck's air brake system and channeling it – either with hoses or through axles – to the tire. Some systems constantly have air pressure in the axles or hoses. Others only pressurize these areas when additional tire air pressure is needed. Systems also differ in how they monitor tire air pressure. Some constantly monitor, while others do it intermittently.
Don't confuse tire inflation systems with tire pressure monitor systems, which can only alert a driver that a tire needs air, leaving it to the driver to find an air hose to get a tire back up the proper level. The advantage of these monitoring systems is they cost less than tire inflation systems. Also, most tire inflation systems are not designed to provide air to every axle on a tractor-trailer (although that looks like it's starting to change), while many tire pressure monitor systems can monitor every tire on the rig.
Naturally, each tire inflation system manufacturer will tell you their system is the best at delivering air. For every pro and con reason one manufacturer will tell you about their system, another will tell you exactly the opposite. The key is not to get hung up on such details, but rather to investigate the different systems to find out which will work best for your operation, including what kind of dealer network and support they offer.
Here's a rundown of the five major systems and latest developments from each. (Except where noted, these systems are currently able to service only tires on trailer axles.)
Meritor Tire Inflation System by PSI
The ThermAlert is a new optional feature that can warn the driver of a potential wheel end high heat situation that could cause a trailer tire or wheel-off.
"It works in conjunction with the tire inflation system, so by using common elements, this very valuable option is quite cost effective and very simple," says Frank Sonzala, executive vice president of Pressure Systems International. ThermAlert is available on either OEM or aftermarket levels for all trailer axles.
PSI says its system can also be mounted on the truck's steer axles, with some modification to the axle. PSI is also working to develop a system that can be used on the drive axle, an external system now being tested in South and Central America.
Dana Spicer Tire Inflation Management System
A couple of years ago, Dana Spicer announced a joint technology initiative with Bendix Commercial Vehicle Systems that allows for the integration of TIMS with TABS-6, a scalable antilock braking system for trailers. The move, they say, simplifies installation and serviceability of TIMS through the elimination of a major component and duplicate wiring on a trailer.
While this system is only for a trailer's axles, the Dana Spicer TIMS SmartWave Tire Pressure Monitoring System, introduced last year, is able to monitor tire pressure on all of a tractor-trailer's axles.
Hendrickson TireMaax
TireMaax has been updated just a bit since it hit the market a little more than three years ago. They are now using a threaded connection to hook up the air lines to the rotary union. Previously the system used a crimp type connection, requiring a special tool. This change makes it easier for the trailer OEM or the aftermarket user to install the system. Early this year the company published a troubleshooting interactive CD to assist technicians in maintaining the TireMaax system.
Airgo Systems LLC
Airgo plans to launch a new generation of products later this year, according to President Tony Ingram. He said it will reduce the installation workload for OEMs and those doing retrofits to existing trailers.
It will allow a more universal application that will not require special hubcaps or the alteration of hubcap rings. The new systems will provide greater protection from the elements. New flow sensing technology will offer options relating to real time reporting, trailer tracking, unauthorized removal of trailer components, trailer mileage, and alert notification of tire issues such as temperature and pressure information, that is automatically and readily transferred to hub locations and maintenance facilities.
Airgo also will introduce an independent drive axle system that will cover all drive train tires, even if the trailer is not equipped with automatic tire inflation. The two systems will work independently of each other or together.
Safer Corp.
Safer's Vigia system, first introduced in Argentina in the 1970s and in the U.S. in 2000, is one of the most different systems out there. Unlike the others, this system is external, with the air hoses leading from the tractor or trailer to a rotor on the wheel hub rather than going through the vehicle's axles. This means the system can service all of a tractor-trailer's axles.
Safer has replaced the 2 1/4-inch rotor with one that's only about an inch thick, making the rotor less susceptible to damage and longer lasting.The company has also changed the bearings in the hub, leading to greater life expectancy, with a warranty upped to 200,000 miles on each rotor.
No matter what system you decide is right for you, they all offer a return on investment in 12 to 18 months, say the makers.
Tire Talk continued...
