October 1, 2015 by JEAN BURROWS
The importance of the cab in a vocational truck can’t be overstated. Your driver spends 95 per cent of his time there … not looking at the shiny grilles and spiffy paint job on the exterior. Those of us who drive a desk all day appreciate the comfort and efficiency that comes with a customized, ergonomically correct workspace. It’s slightly different for drivers – in addition to those considerations, safety is of key importance when navigating the hazards of highway driving and crowded job sites.
We surveyed seven vocational truck manufacturers about the features of their vehicles (such as dump trucks and concrete ready-mix trucks) that are specifically aimed at keeping drivers comfortable, productive and safe.
Driver comfort and satisfaction is a major trend in dump-truck design, according to Kevin Baney, chief engineer at Kenworth Truck Co. He points to features such as a larger interior, a more logical dash and switch layout, better braking performance, and information centres with instant feedback as having the potential to improve the driver’s experience both on the road and at the job site.
“We actively engage customers for their feedback on cab design, both during the development process and after the product is in the field,” says Charles Cook, marketing manager for Vocational Products at Peterbilt Motors Co. “The cab designs of our Model 579 and 567 were the result of the most extensive research and development in our company’s history.”
Peterbilt worked closely with customers throughout the design process to refine every detail – from pedal and gauge placement to the look and feel of the materials, Cook says. “It’s a large investment to change the overall design of vehicles, so we make those changes strategically and don’t make big changes very often,” says David Hillman, vice president and general manager of Navistar’s vocational line. “But there’s never such a thing as a perfect spec. Continuous improvement is the phrase that describes our approach.”
Navistar made major changes to its steel-cast vehicles about 10 years ago, at which time various ergonomic improvements were made. “We paid attention to such things as the location of dials and switches (and how this impacts drivers’ reach) and head turn (how easy it is for drivers to see what’s around them).
“We studied what tasks drivers performed in a day and how often, then built CAD models to test the human interface design. We then shared those results with clients in a design clinic – bringing in customers and drivers as an additional litmus test.”
“Ergonomics and comfort go hand in hand. We design the interiors to maximize operator productivity and minimize driver fatigue. We do this through designs that enhance ergonomics and optimize comfort,” says Cook.
“Ergonomics involves almost every area of cab design – gauge placement and illumination, interior lighting, visibility, pedal position, arm rests, seats, etc.,” says Cook.
Western Star, for example, offers large, waterproof switches that allow drivers to work with their gloves on and are protected from water and salt which can create shorts. And once the product is in the field, the market provides feedback if there’s dissatisfaction with an existing design.
“The fleet managers will let us know what feedback they’re getting from the drivers,” Hillman says.
“We do customer satisfaction surveys and collect data through several channels, but the most important measure is direct communication with customers and dealers,” says Cook.
“Peterbilt and its dealer network stay engaged with customers throughout the ownership experience and take the feedback that we get very seriously.”
The manufacturers offer various levels of customization – from interior finishes to seating to gauges. Navistar’s Diamond Logic electrical system allows for customization within the control panel, for example.
Wing panels reduce reach distances by swinging the panel closer to the driver. This can be handy on concrete mixers, which typically don’t carry passengers, but could encroach on passengers’ leg space in dump trucks or those used for paving installations that might have two or three people riding in the cab.
Cab design can reduce driver fatigue, allowing them to remain focused and productive throughout the shift, says Andy Hanson, North American Vocational sales manager at Volvo Trucks. “Separate inner and outer door seals keep elements and noise out, while the thick floor covering dampens noise and provides thermal insulation,” he says, adding that the noise level within cabs is typically 72 to 77 decibels.
Both Peterbilt and Mack indicated that cab interiors can be customized to meet the full range of customer requirements and preferences. “Automatic and automated transmissions continue to gain share every year. They reduce operator fatigue and can improve fuel efficiency,” says Cook. “Particularly with the industry’s shortage of drivers, operating a truck with an automatic or automated transmission can help lessexperienced drivers perform like a more seasoned driver.”
Mack also credits the increased use of automatic transmissions in helping reduce driver fatigue. Physical comfort is important when you’re spending seven or eight hours sitting. Standard level features of Volvo seats include contoured cushions, a seven-in., fore-and-aft slide and a power air lumbar support. Additional features, including heated and extra-wide cushions, are offered at the Comfort level.
Steering wheels and steering columns can be adjusted for optimum drive comfort, while switches located on the steering wheel and stalk allow drivers to operate frequently used controls without taking their eyes off the road. When Kenworth added four in. of space behind the seats of the T880 vocational truck to allow for more seat travel, it also opened up space on the back wall to hang coats and hard hats.
Of course, cab comfort depends on sitting on a forgiving chassis.
At Mack, the Granite galvanized steel cab is mounted on airbags and shocks and the chassis is engineered to allow maximum wheel cuts to provide superior maneuvering in tight spaces. Air suspension is standard on Volvo trucks. Rear cab suspension air bags are mounted outside the frame rails for greater cab stability when cornering, while lateral shock absorbers reduce swaying of the cab.
Hardened rubber dampeners in the suspension system help absorb the impact of a severe shock to the cab. Western Star offers rubber bump stops to provide an improved ride over rugged terrain. Freightliner mentions that its suspensions reduce axle vibration, resulting in a smoother ride for drivers.
Visibility is one of the most important operating features at a job site, says Baney of Kenworth. The windshield in the T880 is 50 per cent larger than its previous generation cab to give drivers a better view of the terrain, obstacles and workers around the truck.
All of the manufacturers mentioned windshield design and placement as important features.
Freightliner’s 114SD also touts outs
tanding visibility from a 2,500-sq. in. windshield and downward sloping cab hood. It also features a low step-in height and strategically placed interior and exterior grab handles.
Volvo’s VHD cabs feature a panoramic, one-piece windshield, slim A-pillars, and sloping side windows to increase drivers’ visibility. “You always have a solid, three-point entry on Volvo trucks,” Hanson says, pointing out that the grab handles are located on the interior of the cab. This eliminates hands slipping off exterior handles that are wet from snow or rain.
Bluetooth-equipped steering wheels are standard on the VHD cabs, so drivers can use the phone hands-free, as are air bags. Lane departure is a common cause of highway crashes and Volvo includes lane departure in its driver alerts. A windshield mounted camera tracks the road markings and provides audible and visual alerts if the driver has drifted out of lane.
Remote diagnostics also impact driver productivity by letting maintenance staff determine whether flagged issues can wait to the end of the day, or the weekend. Last year, Volvo started monitoring its automated manual transmission (I-Shift) as well as the engine.
“Previously, if drivers saw a light come on in the instrument panel or a code they didn’t understand, they might have just parked the truck for the day to avoid damage,” says Navistar’s Hillman. “We say (remote diagnostics) takes unplanned downtime and turns it into a planned maintenance activity.”
GuardDog Connect is Mack’s real-time diagnostic and monitoring service. As with other systems, such as Peterbilt’s Smart- Link or Navistar’s OnCommand Connection systems, once the truck arrives at a maintenance centre, the dealer and technicians already have the information and parts they need.
“If there is an increased focus when it comes to cab interiors it is that fleets are spec’ing more premium content and trim levels to help recruit and retain the best drivers,” says Cook at Peterbilt. “With the industry’s shortage of drivers, recruiting and retaining the best operators can be challenging. Obviously equipment plays a significant role in a fleet’s ability to get and keep drivers.”
“The truck’s interior should accommodate and adjust to a wide range of body types and sizes,” Kenworth’s Baney says. “No fleet owner wants to hear a driver say he’s leaving or needs time off because he’s uncomfortable in the cab. The cab should adjust to the driver, not the other way around.”
Ergonomics plays a huge role in dashboard design, ensuring switches are positioned to minimize drivers’ reach and to maximize the time drivers’ eyes stay on the road. Some manufacturers are also incorporating an in-dash display unit.
Mack’s Co-Pilot driver information display provides real-time fuel economy and trip data, along with detailed maintenance and fault summaries and supplemental sensor readings.
At Volvo, the over-sized driver information display presents data on fuel efficiency, trip mileage, battery voltage, and fluid levels. It can also be set to display specific gauges. And the performance bonus display provides real-time driving feedback to help increase fuel efficiency.
Kenworth’s driver performance centre is a five-in., high-resolution colour display with digital gauges that provide real-time operation about the truck’s operation, including oil and transmission temperatures, a sweet-spot visualization of RPM and fuel economy, engine torque, PTO status, and pop-up diagnostic alerts.
At Navistar, the driver information display includes Bluetooth and an integrated microphone in the headliner.
Jean Burrows is a freelance writer based in Guelph, Ont.