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Western Star’s renewed push into the vocational market takes shape in the all-new 49X, which features a bigger, quieter cab and a lighter but stronger chassis. (DTNA)

Western Star ups vocational-truck ante with all-new 49X

Six years in the making, the clean-sheet-designed 49X vocational truck is quieter, lighter, tougher and safer than its predecessors.

Purpose-built from the ground up, the next-generation Western Star 49X vocational truck is underpinned by a stronger, lighter chassis and equipped with a new X-series steel-reinforced aluminum cab that’s claimed to be the segment’s largest with 10 to 13% more space while being 8% lighter. Technology upgrades that bolster productivity, safety and uptime for the vocational market include Detroit Assurance active safety systems such as Side Guard Assist and the Detroit DT12 Vocational series of automated manual transmissions, which debuts on the Class 8 vocational truck.

“We’ve completely rethought the foundation of the 49X to make it easier to upfit,” David Carson, senior vice president, vocational segment, Daimler Trucks North America, stressed during a virtual press event introducing the new truck. Engineers focused on clear back-of-cab packaging and features that contribute to easier upfitting: forward-mounted DEF tanks; standard in-cab battery box; multiple air tank mounting locations; air dryer mounted under hood (SBA) or under cab (SFA); and dual vertical exhaust stacks.

The 49X is the “most tested, safest, most advanced vocational truck” Western Star has ever designed and produced, Carson said. “We’re focused on really making a push in the vocational marketplace.” The company devoted the past six years to developing the truck.

Full-vehicle shaker tests replicated 800,000 miles (nearly 1.3 million km) of use, testing among other things the new cab mount system that uses isolators mounted outboard for stability and reduced operator fatigue. Development work also included multiple cab crush tests to ensure rollover integrity. Real-world testing of prototype trucks by customers also has exceeded 800,000 miles in various applications such as logging, construction, dump trucks and concrete mixers.

Triple-seal doors and additional insulation also contribute to the quietest cab ever developed at Western Star, Carson said. Engineers wouldn’t provide exact figures, but Tracy Mack-Askew, general manager for heavy-duty vocational platforms, said, “We benchmarked competitors but really set our targets based on the on-highway segment so that our truck is tough enough to serve the vocational customer but quiet enough that you could take it on a multi-day trip comfortably.”

Clean-sheet approach cuts weight
The truck’s clean-sheet design enabled a total weight savings of more than 350 lb (159 kg) compared to a similarly spec’d current Western Star 4900. That weight savings starts with an all-new vocational frame, said Carson, noting that the rails save 4.2 lb (1.9 kg) per foot. Single-channel frame rails are available in various thicknesses and feature a claimed best-in-class RBM (resisting bending moment) strength rating for single channel of up to 3.7 million inch-lbs. C-channel frame reinforcements are available that reach an RBM rating of 5.4 million inch-lbs.

A splayed rail design enabled lower engine and cooling packaging, which allows a sloped hood for better visibility through a 28% larger one-piece windshield. New for Western Star trucks, a composite hood system saves 100 lb (45 kg). Constructed of polydicyclopentadiene (P-DCPD), a high-strength, highly impact-resistant thermoset resin material, the new hood uses a patented ISO Tech Hood Suspension system that behaves similarly to a typical coil-over shock suspension with spring and damper. The system isolates, absorbs and dissipates vibrations from the chassis when driving over uneven terrain.

Ergonomic ingress and egress was a major design focus for the 49X. Door opening angles were increased to 70 degrees, step treads were widened by a half inch (13 mm) and a “staircase design” has the steps starting closer to the ground for easier entry. Design engineers also spent years developing a door-mounted C-bar mirror system that mitigates the effects of chassis and engine vibration to keep the mirrors stable even in off-road or paving applications.

Western Star partnered with Hendrickson on the “premium” rear suspension portfolio as part of the chassis enhancements. Hendrickson’s next-generation heavy-duty rubber suspension, HAULMAAX EX, debuts on the 49X, addressing the growing demand for rubber suspensions across all vocational applications, said Ashley Dudding, director of engineering for Hendrickson Truck Commercial Vehicle Systems.

The new suspension expands on the capabilities of the current HAULMAAX design with up to a 70,000-lb site rating for the 46,000-lb capacity suspension. HAULMAAX EX offers capacities of 40,000, 46,000 and now 52,000 lbs, said Dudding, adding that it’s also “the lightest weight vocational suspension on the market.”

The 49X also offers Hendrickson’s ULTIMAAX severe-duty rubber suspension for more extreme applications as well as PRIMAAX EX, a severe-duty vocational air suspension for applications requiring a softer ride. A dual-stage LED headlight system is another first for the 49X. An internally printed heat grid and ambient air temperature sensor can melt 3 mm (0.12 in) of ice in less than 10 minutes at -40 degrees F and can defog the headlights in hot temperatures.

AMTs and active safety
Available as either the DT12-V or DT12-VX (“vocational extreme” variant), the all-new Detroit DT12 Vocational series of automated manual transmissions (AMTs) was validated in more than 35 million miles (56 million km) of testing. Rated up to a gross combined weight rating (GCWR) of 330,000 lb, the DT12 Vocational series can be mated to the Detroit DD15 Gen-5 engine or Detroit DD16 engine. Both engines are equipped with Detroit Connect Virtual Technician remote diagnostic services to increase uptime.

“Over $100 million was invested globally in creating a transmission that could be used in vocational applications,” said Samantha Parlier, VP of Vocational Market Segment Development at Daimler Trucks North America. The AMTs have two PTO openings, one at the rear as on the DT12 on-highway transmission and an 8-bolt left-side PTO. Unique work application modes and shift map strategies are tuned for varied terrain, Parlier explained.

A Rock-Free Mode allows the 49X to free itself from wheel-stuck situations, an Off-Road Mode enables smoother driving on extreme terrain such as logging roads or rock quarries, Power Launch provides takeoff while protecting the clutch and driveline, and a Paver Mode allows the truck to shift from Neutral to Drive without depressing the brake pedal when driving away. Cummins X12 and X15 engines also are available, with Eaton and Allison transmission offerings.

The 49X features the most advanced collision mitigation system in the vocational market, according to Carson. “Safety technology in vocational, there’s sometimes a question if it’s needed. We see it as critically important to be able to change the value proposition of a vocational truck,” he said.

Detroit Assurance offers Side Guard Assist (SGA), Active Brake Assist 5 (ABA5), tailgate warning, adaptive cruise control (ACC) to 0 mph, lane departure warning, video capture, intelligent high-beam and automatic wipers and headlamps. With optional SGA, radar technology detects moving objects and pedestrians on the passenger side of the 49X that may be in the operator’s blind spot. The system provides both auditory and visual warnings.

ABA5 detects moving and stationary objects ahead of the 49X and determines if a warning or automated braking is necessary. ABA5 with Detroit Assurance is the only system on the market that works down to 5 mph, the company claims, making it suitable for jobsites and in congested urban areas. First deliveries of the 49X vocational truck begin in early 2021. It’s being produced in the company’s manufacturing facility in Cleveland, North Carolina.

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