DURABILITY THROUGH INNOVATION

Manufacturers aim to boost durability, and drop weight, in the vocational truck segment.

BY TREENA HEIN

More features, more durability, better performance: all of these, and more, can be expected as competition for your vocational truck order continues to heat up. In addition to addressing the expectations for improved operator comfort and upgraded sensor networks, today’s vocational truck manufacturers are making the vehicles more durable than ever, but there’s more going on than just a show of strength.

“In the context of the construction industry, not only is durability required, but weight reduction is equally critical,” explains Michelle McConn a heavy-duty vocational product marketing specialist at Daimler Truck North America (DTNA), the manufacturer of the Western Star X-Series and Freightliner Plus Series.

In the X-Series for example, more durability but less mass is found in the single frame rail, hood, cab and air intake system. This helps mitigate today’s high manufacturing costs while also providing a bit of fuel savings during operation.

DTNA is approaching weight reduction through targeted placement of reinforcement. The cab in the new X-Series is aluminum, for example, has strategically placed steel reinforcements in the pillars that enable the cab to withstand such factors as extreme-duty door slam cycles over the truck’s lifetime. In addition, the use of factory-installed features that streamline body integration eliminates the need for truck equipment manufacturers to cut through the cab or dash for body controls and power. McConn adds that both the X-Series and the Plus Series offer the QuickFit system, which involves factory-installed features that maintain durability and reduce noise.

Turning to the entire frame, McConn explains, “The new single-channel frame rails remove the need for double-frame rails by offering thicknesses from 8 mm to 15 mm and providing a resisting bending moment [a measure of material yielding strength] of up to 3.8 million inch-pounds.”

The new rails, she says, provide weight savings of about 100 pounds while still providing the strength required to forego the need for frame rail inserts. The new single-channel rails are also designed to minimize corrosion.

Suspension is another area where vocational trucks are getting a durability upgrade, and a reduction in weight. The Mack mRIDE rear suspension, offered in 40,000-, 46,000- and 52,000-pound load capacities, offers reduced weight when equipped with Mack axles, explains Tim Wrinkle, construction product manager at Mack Trucks. That option trims 140 pounds with drum brakes and 146 pounds with air disc brakes.

“This suspension is popular because it offers a smooth ride on the roughest jobsites,” he adds. “It provides extreme articulation with its spring leaf suspension over rubber block suspension, maintaining high stability and minimal roll rate. It also offers greater ground clearance than other suspensions due to the use of the spring leafs over four separate rubber block pads.”

According to the manufacturer, the rubber isolated upper v-stay and lower torque rods, arranged in a parallelogram, keep the forward and rear drive axles at the same pinion angle through the articulating range.

Mack Trucks has also taken the approach of top mounting its axel carriers, a design that delivers a straight-through driveline that it says cuts down on vibration and should reduce lifetime maintenance costs. Each carrier’s double-reduction gearing means that loading is balanced over two gear sets and the design of the Durapoid bevel gears eliminates localized stress and tooth-end loading, extending gear life and providing better fuel economy.

Hoods And Engines

Newer materials are also being integrated into newer trucks. The X-Series hood is now made of a moulded resin. Polydicyclopentadiene, or P-DCPD, is a highly impact-resistant material that’s also flexible and weighs 100 pounds less than the previous fibreglass hood.

“We’re also seeing a trend toward components that can withstand the magnesium chloride and calcium chloride solutions used to treat the roads,” adds Andy Hanson, director of vocational marketing at Navistar. “Be on the lookout for more galvanized and stainless-steel components to winter-proof your trucks.”

Engine durability is yet another current focus. Hanson explains that the S13 Integrated Powertrain for his company’s Inter- national line was created from the ground up with a focus on simplicity. Design simplification, he notes, goes a long way in keeping trucks on the road longer.

He adds that the powertrain takes “a big step forward in durability by releasing an engine that no longer requires an EGR cooler or diesel oxidation catalyst/seventh injector to reach today’s stringent emission regulations.”

DON’T FORGET THE PTO

With the release of S13 Integrated Powertrain, International now joins others in the market in offering factory-installed PTOs. This reduces upfitting times and increases first time quality.

Vocational models from Mack Trucks have PTOs and hydraulic pumps mounted to the mDRIVE transmission direct from the factory.

“This is a very popular choice on Mack Granite models because it makes upfit even quicker and easier,” says Wrinkle. “We also have new options such as the mDRIVE –Dual PTO.”

For the Freightliner Plus Series and the Western Star 47X/49X models, quick access to PTO functions is now provided through the display screen.