Freightliner Vocational Cabs: Built to Serve
In the last issue of the Severe Duty Report, we began our tour of Freightliner’s Mt. Holly, N.C., production facility, by taking readers through the chassis assembly process. The 637,000 square foot plant is just too big, too complex, and way too interesting to cover in a single article, so in this issue we continue our tour with the assembly of our Business Class® M2 and Severe Duty truck cabs.
The Freightliner Trucks’ steel-reinforced aluminum cabs are designed to provide many years of productive service, often in extremely challenging working conditions. And that means that even the production process is extraordinarily rigorous.
“We maintain our commitment to quality throughout the process,” says plant manager Erik Johnson, “with quality gates, inspections and process audits at every step.” The Freightliner vocational cab is extremely well-designed, constructed and tested. For example, the cab is subjected to the rigorous Swedish A-pillar test, where a 3,300 lb. steel barrel strikes the cab’s A-pillar again and again with more than 21,000 foot-pounds of energy.
Like the chassis and engines that are assembled on separate production lines, the cab assembly includes both robotic and manual steps, for maximum efficiency with meticulous attention to detail.
Freightliner’s Severe Duty trucks are very well designed, constructed and rigorously tested. That painstaking attention to detail throughout the process helps ensure that these trucks will deliver many years of productive service.—Erik Johnson, plant manager, Freightliner Trucks ”
The cab sub-assemblies are joined with Henrob rivets and structural adhesives to form a unitized structure with remarkable strength and consistency.
In a “belt and suspenders” approach, structural adhesive is applied between inner and outer aluminum structures before they are riveted. Instead of conventional rivets, the trucks are constructed with Henrob self-piercing riveting, a cold joining process that fastens sheets of material with engineered rivets. Unlike conventional riveting, self-piercing rivets do not require predrilled holes and, because the rivets do not completely penetrate the metal, they eliminate potential leaks through the riveted joints.
The cab floor deck is assembled with preset sidewall and backwall assemblies, and the steel firewall then is added. The entire cab assembly is transferred to a large, multi-stage framer, which aligns the sub-assemblies and joins them together permanently with self-piercing rivets. More self-piercing rivets and structural adhesives are incorporated as hood supports, roof skin and doors are added.
The entire cab structure is thoroughly checked for accuracy before the cab moves on for e-coat priming and final paint. In the e-coat process, the raw metal cab is completely immersed in a 20,000 gallon tank. The solution fills the entire cab—every nook and cranny, every cavity, inside and out—covering all interior and exterior cab surfaces to help deliver superior corrosion protection.
Final cab assembly includes all interior components: the electrical harnesses, seats, dash, glass and floor mats. Finally the cab, hood, and chassis are joined together. Every truck goes through multiple functionality tests, including a dynamometer to simulate a road test, ABS brake test, and water test. Every step is checked and double-checked before touch-up paint and a final inspection.
“Freightliner’s Severe Duty trucks are very well designed, constructed and rigorously tested,” says Johnson. “That painstaking attention to detail throughout the process helps ensure that these trucks will deliver many years of productive service.”
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