By Marek Krasuski:
More than ever before consumers in the medium duty markets have a wide range of spec’ing options to get the right vehicle tailored to their specific needs and to reduce total cost of ownership. Tightening regulations, demand for greater fuel economy standards, efficient designs with aerodynamic features, interior comfort and space play as much a critical role in the manufacture of cabs as in other truck components and parts. To be sure truck owners are willing to shoulder the additional cost burden for such add-ons, as long as they are convinced that savings will accrue in a reasonable payback period. Moreover, competition among truck builders is predicted to increase over the next few years, so there is a willingness on the part of manufacturers to provide their customers with the best bundle of money-savings features possible.
The need for sleeker, lighter and more efficient cabs is behind the shift toward lighter materials than steel, the traditional option in truck cab construction. Truck cabs and bodies are increasingly constructed with carbon fiber that weighs no more than a few hundred pounds, a potentially huge savings considering that a 10 percent reduction in body weight amounts to a 6 to 8 percent increase in fuel efficiency. Less body weight means more loading capacity which results in fewer trips and less fuel and vehicle wear and tear. Lighter vehicle weight also translates into reduced maintenance costs as lighter vehicles put less stress on tires and brakes. Weighing half as much as steel and just as strong, carbon fiber is gaining favour. However, the material is costly and there are difficulties in the painting process, namely, trying to get the surface as smooth as a polished steel surface. Carbon fiber is closer to a fabric than to metal with fiber substrates that render a surface porous and inconsistent. This results in imperfections in the finished painted surface such as paint clumping on parts of panels.
While carbon fiber cabs have their challenges, aluminum cabs too are playing an increasing role in reducing cab weight and improving fuel economy. Truck builders in both heavy duty and medium duty markets are transitioning to aluminum to limit cab weights so vehicles can carry more cargo and trim back fuel costs.
But steel, traditional material for builders, has been and continues to be in popular use, and for good reason – principally the ease of manufacture compared to aluminum. 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.
Whether steel, carbon fiber or aluminum, the attention the industry pays to aerodynamic features on truck cabs is well worth the effort. These include everything from changes to the hood, roof fairings, fenders, bumpers and mirrors. According to a Report authored and published by the North American Council for Freight Efficiency (NACFE) the removal of aerodynamic features can result in a 10 percent reduction in fuel efficiency. The Report also compared traditional styled tractors to newer aerodynamic models and found the former about 30 percent less fuel efficient than later builds. Savings also apply to day cabs.
A review of product offerings shows how truck builders are responding to the demands of the day. Kenworth offers a range of cab options for the medium duty market, namely the T270, T370 with conventional cabs and the K270 and K370 cabovers. The Class 6 K270 and Class 7 K370 are best suited for municipal delivery applications promising payload, productivity, reliability and uptime. Cabs are comfortable and quiet, and include multi-function steering wheels with adjustable column, heated mirrors and windows. Dashboards are designed so that gauges are readable at a quick glance. Critical information such as speed, engine rpm, oil level, fuel consumption, trip data and turbo pressure are instantly available in the colour master display module. These medium duty cabovers optimize payload thanks to a lightweight, durable chassis constructed of 120,000 psi-rated steel and a frame with 34-inch rail spacing. In addition to customization of cabs in their medium duty trucks, the company pays equal attention to providing a range of axle specs, all-wheel drive, body builder alignment and custom frames.
Also focused on tailoring design to customer demand, Navistar is similarly committed as much to the customization of chassis as to cabs in its International medium duty truck line, including the heralded International Durastar, its class leader. This includes the location of components such as exhaust systems, air tanks and battery boxes. A wide variety of resilient huck-bolted chassis are available to accommodate a breadth of applications – dump, emergency, propane/compressed, utility, and refuse. For example, bolt-on frame extensions allow for plows and other attachments and additional reinforcements enable trucks to carry heavy loads and meet other severe-duty demands. Navistar highlights durability as a main feature in cab design. The shell is made from high strength, low alloy double sided galvanized steel and standard cold rolled steel. A specific painting process resists corrosion and fading and is backed by an unlimited 12-month warranty. (A standard 7 year warranty covers the frame.) And one piece of steel surrounds the entire door opening for superior structural integrity. A 3-piece hood reduces costs in the event of an accident. If a collision occurs, it is likely that only certain sections will require replacement.
In 2017 Volvo introduced cab makeovers for its VHD series in both day cab and regional sleeper models. The suite of changes is designed to optimize driver comfort and efficiency with features like a variety of seating options. There is greater reach in the fore and aft and up and down range for better ergonomics. Seat heating and ventilation options are also available, as is a refrigerated passenger seat to provide a cool place to keep food and beverages. Among the available tech toys are an optional infotainment system with 7-inch colour touch screen, audio system, and Bluetooth and Apple CarPlay for maximum connectivity. Further, all controls are within easy driver reach with most built into the steering wheel which is attached to an air assisted, fully adjustable steering column. This enables drivers not only to tilt and telescope the steering column, but also tilt the wheel relative to the column. The VHD 300 Axle Back straight trucks and tractors are available with easily customizable chassis and up to nine power take-off options.
With a view toward driver retention, an ever present problem in the industry, companies today, more than ever, are tailoring work environments in the truck to be as user friendly as possible. Comfort, ease of operation, visibility, and maneuverability figure prominently into the design and build process. Peterbilt’s medium duty class trucks aspire to achieve driver comfort and productivity. Most models in the medium duty range feature an ergonomic dash with LED easy-to-read gauges and information display unit charting critical vehicle data. An in-mould process embeds colour directly onto the dash for a long lasting finish which eliminates fading, scratching and peeling.
Freightliner also subscribes to the need to keep driver comfort and productivity in mind through the design and development of medium duty trucks. The company has also kept in mind the need for reduced cost of ownership in the ongoing development of its M2 models. The M2, particularly the M2 106, serves a wide range of medium duty applications from dump and flatbeds to delivery, refuse and utility vehicles. Freightliner has reinforced both cab and chassis with added strength. The M2 chassis includes a backbone with single or double channel frame rails with a tensile strength of up to 120,000 psi and an RBM ratio up to 3.7 million inch-pounds per rail. Translation? The 106 can withstand a lot of demanding work. The cab too is extremely strong, yet lightweight, thanks to corrosion resistant aluminum reinforced with e-coated steel and welded construction. The cabs come with a sloped hood, low profile dash, and a 2,500 square-inch windshield the offers the best in-class visibility.
With the age of drivers exceeding the national average, many retiring or leaving the industry, the medium duty market is paying as much attention to driver demands as the long haul sector. All improvements in cab design that add comfort, safety and productivity to drivers stand to enhance the profession, making it more attractive to newcomers and hopefully encouraging existing drivers to stay.☚