Tuned tractor-trailer suspensions boost stability

Oct. 1, 2007
Hendrickson Truck Systems Group officials announced the company's new 1+1=3 integrated tractor and trailer suspension arrangement during a press conference

Hendrickson Truck Systems Group officials announced the company's new 1+1=3 integrated tractor and trailer suspension arrangement during a press conference August 22 at the Great American Trucking Show in Dallas, Texas. Key benefits include improved roll stability, reduced tire wear, and lower weight (about 405 pounds).

A new tunable, platform-based system will be rolled out in 2008 on an as-yet-undisclosed truck chassis. The system will include an HTB drive axle air suspension and Airtek steering axle air suspension. For optimum performance, tractors with the new suspension system would be combined with trailers that have a Hendrickson suspension.

Gary Gerstenslager, Hendrickson president, said that improved roll stability is one of the biggest benefits of the integrated suspension approach. Videos taken on a test track showed a dramatic improvement in tractor-trailer stability. Gerstenslager cautioned, however, that the 1+1=3 system isn't intended to replace the roll stability systems that work with the antilock braking.

The company also announced availability of the PRIMAAX heavy-duty air-ride rear suspension on International trucks. Launched in 2003, the PRIMAAX drive-axle suspension has performed well in rugged vocational applications, according to Hendrickson officials.

International now offers PRIMAAX 46,000-lb capacity and PRIMAAX 23,000-lb capacity suspensions on all PayStar and WorkStar series trucks. Heavy-duty forged support beams, premium outboard mounted torque rods, and a highly engineered cross brace combine to deliver greater roll stiffness as compared to other rear air-ride suspensions. The suspension has large volume air springs and premium, heavy-duty shock absorbers for outstanding handling characteristics that can provide the driver with greater control during lane changes, highway ramp operation, and tight road maneuvers.

Hendrickson officials said the company had squeezed 75 pounds from the INTRAAX low-ride/liftable integrated trailer suspension system with the launch of the INTRAAX AANL 23K, which replaces the AAL 23K. The suspension is designed for use with drop-deck, lowboy, platform, tanker, bottom dump, and specialty trailers.

The AANL system uses Hendrickson's Advanced Axle/Beam technology (AXT), which teams tapered beam and Large Diameter Axle (LDA) technologies to enhance strength and reduce weight. LDA increases the diameter of the traditional five-inch axle by about three-quarters of an inch while slightly reducing wall thickness. LDA delivers as much as a 22% increase in bending and torsional stiffness compared to the five-inch axle tube.

In response to customer requests for a more basic tire inflation system, Hendrickson Trailer Suspension Systems engineers developed TIREMAAX CP (Constant Pressure). TIREMAAX CP continually checks tire pressure without pressurizing the axle or wheel ends and employs a pneumatic controller to direct air to tires that fall below a preset pressure level. A signal light illuminates only when attention is required to alert the operator of tire or system leaks. With robust components and no electronics, transducers, or pressure switches, TIREMAAX CP is easy to maintain. The versatile CP requires no special tools to adjust tire pressure settings and operates on either 12- or 24-volt electrical systems.

The original TIREMAAX product now is called TIREMAAX EC, and it will continue to provide full tire inflation system programming and monitoring. The patented system draws from the trailer air supply to keep trailer tires properly inflated and rolling smoothly.