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Designing a vocational frame to stand up to heavy vocational demands

David Sickels is the Associate Editor of Tire Review and Fleet Equipment magazines. He has a history of working in the media, marketing and automotive industries in both print and online.


At the end of September, Western Star introduced its new 49X vocational truck built from the ground up—and that included re-thinking the chassis.

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According to Samantha Parlier, DTNA’s vice president of vocational market development, the truck is underpinned by a stronger, lighter chassis and equipped with a new X-series cab. She says the design of the Western Star 49X brings a total weight savings of over 350 lbs. in like-for-like spec’ing versus the current Western Star 4900, and that weight savings starts with a new vocational frame.

“There’s a couple of different things that make a vocational frame, and one of them is obviously the strength. Our new single-channel, 15 mm rail is the strongest in the industry,” Parlier says. “It provides 3.7 million RBM, which is ‘resistance to bending moment.’ So, that’s how much can the truck take before it’s going to bend, and that’s important. You’re putting equipment on here. You don’t want the rail to bounce around and damage equipment, you want it to live for the life of the truck: twenty-five, 30, 35 years.”

Multiple parent rail front frame extension options are available for applications requiring front-mounted equipment, such as a plow, the company adds.

“The crossmembers are bolted, so if you do have an issue in the field, you can take this out and replace it without having to tow the truck somewhere,” Parlier says. “You can design a frame so that your spacing is accurate, so you can put your pump in here for your mixer body. And know that we have tested the living bejesus out of it.”


Western Star also designed the chassis routing and clipping structure underneath to help prevent mud, snow and other debris from building up on the undercarriage.

“Nothing is rubbing, nothing’s chaffing, so this harness is going to last in the most severe of environments and keep running regardless of where it’s being used,” Parlier says.

“And I would just add to that, that we’ve seen customers and dealers have talked to us extensively about that,” says David Carson, DTNA’s senior vice president of sales and marketing, vocational segment. “And we have seen trucks that come back from the field in the shop, and they show us all the spot where we might have snow accumulation, or we might have mud, or rocks, or whatever. Obviously, these trucks are abused to no end, and we got that feedback and input and integrated that into our development process.”

Under the hood, the 49X debuts the new Detroit DT12 Vocational series of automated manual transmissions. Available as either the DT12-V or the DT12-VX, the transmission can be mated to the Detroit DD15 Gen 5 engine or Detroit DD16 engine, both of which come equipped with Detroit Connect Virtual Technician remote diagnostic services. The truck also comes standard with the Detroit Assurance suite of safety systems.


The Western Star 49X will be available for ordering this winter and first deliveries are planned to begin in early 2021.



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