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March Theme: Cabs & Chassis

Charting Developments in Cab & Chassis Design

By Marek Krasuski

Still early in the New Year, trucking could prove to be a challenge in the months ahead. Supply chain issues will press the industry, in part because of unresolved trade and tariff disputes which can directly impact upon transportation activity. For example, when the Trump Administration imposed a 10 percent tariff on steel from China they retaliated with a 25 percent tax on soybeans. China is a large consumer of American soybeans, so American Carriers were impacted by diminished demand for this foodstuff. It remains to be seen what effect steel tariffs will have on cabs, chassis and related products, though there are some telling indications. It is true that truck and trailer prices have not spiked as much as anticipated – yet! But by the same token dump bodies did rise 11.5 percent in September 2018 over the same period in September 2017, and light duty trailers reached a 9 percent increase. Since dump bodies contain more steel than other body products the significant price increase came as no surprise. In other areas of the market reduced demand for residential housing impacted trucking as it represents 25 percent of fixed investments for Carriers. Further, companies have been building large inventories of imported products, thereby reducing demand for freight services. But every sector experiences several business cycles, typically expansion, boom, peak, and depression before returning once again to a phase of expansion. So the industry continues to forge ahead in spite of the peaks and valleys. It’s the inevitable cost of doing business. Cabs and chassis are one sector of the market that continues to evolve. Daimler Trucks North America (DTNA) is easing the truck driving experience these days with enhancements to the 2020 Freightliner new Cascadia. Cab improvements include Aerodynamic Height Control where the height of the cab is lowered electronically once the vehicle reaches 55 mph. Lower aerodynamic resistance results as air flows more efficiently over and under the front of the truck to reduce drag. Safety measures are in place with the installation of Side Guard Assist which identifies objects in the blind spot of the passenger side view mirror and on the trailer. In addition, enhanced steering features are integral to the Cascadia’s Level 2 automation. Drivers can have both lateral steering and longitudinal control. Plans are underway for further automation. Elsewhere Volvo has added advanced work stations with ergonomic features to its VNL 760, 740 and VNX 740 models. The workstation is multifunctional, changing from a sitting area with cushions that easily unfold into a bed. Additional enhancements include an angled table for easy seating, a 103-degree cushion seat angle to improve seating comfort, and connected cushions that can be easily secured to allow for adequate rest. Volvo describes the workstation as a prominent feature of the cab by providing drivers with the flexibility to personalize their living space while on the road. Testifying to its utilitarian and comfort level Volvo said: “This advanced workstation is the latest example of the emphasis Volvo Trucks has placed on enhancing driver comfort and driver productivity. The ability to create an exceptional all-in-one living space and working environment is essential to attracting and keeping drivers.” Meanwhile Fiat Chrysler has made improvements to its medium duty 2019 Ram chassis and cab. It provides greater weight rating of up to 43,000 pounds including cab and chassis, and a maximum payload of 12,510 pounds. The Class 4 and 5 chassis cabs are becoming robust, so much so that they are competing with the Class 6 models. The Ram’s cab has a larger center console with 12 storage combinations. The console comes with five USB ports for faster charging. Optional 115-volt plugs can charge power tools at up to 400 watts. Chassis design includes standard cab for driver and passengers and bare frame rails, wheels, axles and tires. Contractors then complete modifications for required applications – dumps, tow trucks, emergency vehicles etc. The truck frames are now being built with up to 97 percent strong steel strength and have eight cross members with 34 inch spacing. Ford, too, has beefed up construction of its chassis cab for the Class 3-5 Super Duty truck. Cabs are constructed with high strength military grade aluminum alloy, ensuring superior strength. Stronger, yes, and with the benefit of lighter weight. Ford says the reinforced cab is more resistant to dents and dings and less vulnerable to red rust corrosion. Chassis components are similarly robust with a frame stronger than previous generations. Axles, suspensions, brakes, and drivelines are larger, enabling trucks to take on tougher jobs. The need for sleeker, lighter and more efficient cabs is behind a partial shift toward lighter materials than steel, the traditional option in truck cab construction. But it’s hard to migrate too far away from this traditional resource. One reason is ease of manufacture compared to aluminum or other alternatives like carbon fiber. Creases, corners, angles and bends are not as easily formed with aluminum. Steel is better able to accept sharp angles as its resilience can withstand the pressures of being drawn deep into machines. Stamping tools that shape materials for cabs do not work as well with aluminum due to an effect called springback, a tendency for aluminum to bounce back to its original shape; this despite the fact that aluminum is a lighter material. Profiling truck cabs calls for some discussion on the importance of aerodynamic designs. The industry invests heavily in aerodynamic features on truck cabs, modifying everything from changes to the hood, roof fairings, fenders, bumpers and mirrors. The absence of aerodynamic features, particularly on lon haul tractors subject to persistent aerodynamic drag, can result in a 10 percent reduction in fuel efficiency. Studies have found that compared to traditional styled tractors, newer aerodynamic models achieve 30 percent more fuel economy. In the On Highway market it seems there is no end to the improvements in efficiency and driver comfort. Kenworth’s W990 is a case in point. The cab’s latest long hood classic appearance makes a strong presentation with a length of 131.5 inches from bumper to back of cab. The interior has hand stitched upholstery with fully adjustable air cushion seats orthopedically shaped for optimal comfort and support. The state-of-the-art dash features multiplexed electronic instrumentation and easily accessible switches and controls. The Peterbilt Model 579, which can be spec’d for virtually any application, comes in both day cab and sleeper configurations. The cab, Peterbilt says, has been designed to fit around the needs of the driver. Plenty of leg room and fully adjustable steering column add to the spacious ergonomically designed interior. The sleeper doubles as an efficient workspace; a retractable desk top provides a convenient surface work area and storage space for a laptop. The cab is equipped with new sound abatement technology that minimizes outside noise. With a call out to drivers for feedback, Navistar has modified many features to improve driver comfort with a view to fuel consumption as well. It has improved aerodynamic contours of the hood, fenders, wheel openings and chassis skirts, modifications made after wind tunnel and coast down testing. Interior changes include a column shifter which is now attached to the steering column so drivers can keep their hands on the wheel at all times. More space has been added for additional elbow, hip and leg room. Door openings have been enlarged to improve entry and egress. A new one piece window allows for more unobstructed side views with better placement of cab and hood mirrors. Repositioning of displays and controls are within easier reach as well. Navistar also improved door seals to reduce noise for a quieter cabin. With a view toward driver retention, an ever present problem in the industry, companies today are tailoring work environments in the truck to be as user friendly as possible. Consequently comfort, ease of operation, visibility, and maneuverability will continue to figure prominently in the design and build process.

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