The Making of the T680: Designed from the Inside Out To Create a New Level of Comfort and Performance

If you ask Kenworth engineers, the numbers say it all: 75, 850, 100,000 and 10.

"Seventy-five fleet and maintenance managers, 850 drivers and nearly 100,000 trucks represented, all provided input to Kenworth with a goal of creating a new level of performance in a truck that ups the ante in comfort and ride for drivers," said Jim Bechtold, Kenworth director of product planning. "The new Kenworth T680 also raises the bar when it comes to fuel economy, with a 10 percent enhancement in aerodynamics, which translates to a 5 percent fuel efficiency improvement. For over 27 years, we've been known to offer the industry's most fuel-efficient trucks, beginning with the introduction of the Kenworth T600."

Inside Out

For the T680 project, Kenworth built the truck from the inside out.

According to Bechtold, today's drivers are different in physique than their counterparts of 25 or 30 years ago. And there are more women drivers. "Bottom line is today's drivers need more space; plus adjustable dash consoles. And, what's more, they need more amenities, more integrated technology and a higher level of execution and refinement in their trucks. They see it in their personal vehicles; they want it in their trucks."

Kenworth designed an adjustable test cab that could be lengthened or shortened in all directions. More than 850 drivers participated, adjusting the cab to their liking, literally moving the space between the driver and passenger seats for access to the sleeper; optimizing the steering column; the seat positioning for belly room and seat travel; how foot pedals should be aligned and distanced. All told, it allowed Kenworth to collect data and shape the T680 from the inside out.

"It was exhaustive data collection, but it was well worth it as we found the right size for the cab and entry way to the sleeper," said Bechtold. "Plus, we added four more inches of space behind the seats to allow for more seat travel, accommodating a wide range of driver sizes."

Live, Work, Drive

With a clean slate for the design team, and cab dimensions set, Kenworth engineers came up with criteria for the new truck to be best-in-class in many areas, including: aerodynamics, quietness, comfort, visibility, reliability and durability, and serviceability. "And we wanted that margin of superiority to be significant," said Bechtold. "Not only would we surpass current truck models on the market - and through testing we verified we did - but we would still stand head and shoulders above new models entering the marketplace."

To meet the challenge, Kenworth had a design team mantra: Live, Work, Drive. "These three words encompass everything a truck driver does and we incorporated them every day in designing the T680," Bechtold said. "But we also kept something else in front of us every day: Make money for the customer. This focus helped us on everything from fuel economy, to driver retention to serviceability and dependability, all the way down to re-sale value. It's ultimately what makes a Kenworth."

With a "driver-first" mentality, Kenworth's goal was to optimize comfort, usability and visibility for a wide range of driver types and sizes. "Based on our expandable cab data, we started with the 'Driver's Space,' creating the ideal position for the pedal package, the optimal seating position and steering wheel location," said Wally Peltola, Kenworth design director. "The air-assisted hydraulic clutch we designed only requires half the pressure of a traditional clutch, plus less travel, so it's very easy to engage. It allows a woman in the 5th percentile of size, as well as a male in the 95th percentile to have easy clutch control. That is a major leap forward in accommodating drivers.

"From this seating position we then optimized visibility, through the steering wheel to the gauges, down the road and to the mirrors. We then were able to determine the optimum position for things like side mirrors and grab handles. We designed the graphic user interface for the new Driver Performance Center to ensure that the information was easy to read and understand while being easy to access."

Layout for the dash was critical as well. "Our early clay models of the instrument panel had a lot of wraparound," explained Peltola. "The feedback we received from customers and drivers led to unique enhancements. We reduced the wraparound and placed the most often-used switches closer to the driver and used the further away positions for 'highly-critical' switches - like fifth-wheel slide or suspension dump…things you don't want to inadvertently activate on the road."

Through customer validation, the instrument panel was laid out with an integrated, sweeping 'keyboard' surface that mimics the shape of the driver's reach zone. New toggle switches have a large surface for easy activation and operate with a 'click'. The switch icons also change color when activated for easy at-a-glance recognition.

Kenworth designers then set their sights on the sleeper and dampening sound throughout the cab and sleeper. "If you look at a truck designed 20 years ago, the difference in quietness with the new T680 is absolutely amazing. The T680 is 65 percent quieter in comparison," said Doug Caley, Kenworth's senior engineering manager. "Kenworth has long been known for having one of the quietest cabs in the industry. We analyzed and determined areas where noise could enter the cab and sleeper and put in a unique noise suppressant to dampen noise. That, coupled with a new door design, featuring triple seals, really created an excellent and quiet driving environment."

As for freedom of movement, the stand-up height in the cab and sleeper was designed so a person well over 6-feet in height could move readily in and out of the seats with ample head room. The right side full-height cabinet was segmented to create a dining table and see-through opening. Even the color and material were developed to be lighter above the beltline and darker below offering a spacious feeling.

One of the true "wow" features in the sleeper is the rotating table. "It's unlike any other table on the market," said Peltola. "It's extremely strong. It has a latch underneath to allow the table to rotate out of the way, plus it allows you to leave items - a laptop for example - on the table when it's rotated to the stored position. No longer do you have to remove everything from the table before storing. We think that's a great design element, especially when combined with the optional passenger swivel seat."

Kenworth designers were also proud of the all-LED interior lighting, which includes dome lamps, reading lamps and sleeper lighting. The T680 features an integrated lamp in the door pad that illuminates the steps and the ground below when the door is open. And, like many luxury cars, the T680 features an ambient light in the sleeper and also in the header, which creates a gentle wash of light on the instrument panel and the center console.

Aerodynamics

While most of driver's time in a Kenworth is seated directly behind the steering wheel, Kenworth had to create a truck that also addressed needs of those wearing several hats. "Creating a comfortable truck that is quiet and road hugging - one that is not only fun to drive, but one in which drivers would be proud to drive - was always very important to us," said Bechtold. "But ultimately the truck is a tool to make money. It has to be aerodynamic. It has to be easy to repair and service. It has to last and be durable with low downtime. And, it has to look good."

According to Peltola, the T680 is a great example of combining art and science. "It's the Art of creating a beautiful shape, and the Science of making sure it's aerodynamic," he said. "Every surface we developed was tested and re-tested. Even the marker lights were made flush so not to disturb the airflow. Our design philosophy was that every line should be flowing and every surface should look clean and purposeful. The lines should be a result of beautifully sculpted intersecting shapes. The main character lines on the T680 flow upward and 'lift' the truck. The longitudinal lines of the grille, hood and roof offer stability. This philosophy also applies to the interior. You have to resist over-decoration and visual clutter.

"The exterior design has, in general, a much more integrated look than previous Kenworth models," Peltola said. "The surfaces of the hood and the doors flow into one another in a seamless fashion. The overall impression is of an integrated product rather than a collection of parts and this very much reflects the systems that make up the T680."

For Alec Wong, Kenworth's principal research engineer, the T680 represents a new high mark in Kenworth aerodynamics.

"Our aerodynamics team worked hand in glove with the design team. Once the basic shape was created we worked to refine the design and made the T680 even lower in profile to allow it to hug the road," said Wong. "There wasn't an element overlooked, nor over-analyzed. We even developed a rubber seal under the cab for mid-body aerodynamics. The windshield, in top view, is extremely curved and 50 percent larger. This, combined with the rake of the A-pillar, contributes to excellent aerodynamics."

Serviceability

When it came to creative design work with serviceability in mind, Kenworth analyzed industry averages for vehicle life expectancy, downtime and repairs.

"Another of our goals was to increase actual service life with a goal exceeding 1.5 million miles for the cab and chassis," said Bechtold. "That's far greater than the average life of a truck today. Another goal was to cut unplanned downtime per year in half."

To achieve that, Kenworth looked at all systems and processes. "As an example, through research we knew that 3 to 5 percent of tractors, per year, encounter damage to the side extenders and sleeper," said Bechtold. "Now, that might not seem like much, but for a larger fleet, this could mean a couple trucks every day. To address this, we analyzed the energy load in those areas and designed the T680 to keep that energy absorbed in panels that were easy to replace. If you look at some other trucks on the market, damage to the sleeper will mean extensive repairs both in time and money to the full sleeper and roof fairing. But, should that ever happen to a T680, the repairs can be easily done in the field. The result of the T680 sleeper design is increased uptime for Kenworth customers."

3-D Technology, Computers, Clay

Before the Kenworth T680 ever hit the road, it hit the wall. Not physically, but in the form of light waves and the science of 3-D technology. A 16- by 20-foot 3-D design wall at the Kenworth Research and Development Center in Renton, Wash., helped Kenworth designers and engineers view and almost feel how the T680 would look and perform. "It's a unique and very useful tool that allowed us to better see what we designed in our computers," said Peltola. "It's amazing to see, but it was just the start."

When the look and feel of the T680 was determined, Kenworth designers and model makers brought the truck to life in the form of clay models - 40 percent in scale to start, which meant about 4 feet in height. The design clay - about an inch thick, rested over a skeleton of hard foam, plywood and steel. The completed models were then painted and detailed.

Once comfortable with the design, Kenworth used a laser scanner to digitally record the clay model. The laser measures more than 23,000 points per second. "It took less than a day to laser scan the model - before this laser technology, it would have taken three to four weeks to collect the data points," said Brian Lindgren, Kenworth's manager - research and development. The scanned data was then used by digital modelers to create class "A" surfaces. With the approval to move forward, full scale models were built.

During this time, Kenworth aerodynamics team used traditional and advanced computational fluid dynamics (CFD) and computer-simulated wind tunnel programs. "We still use wind tunnel testing for validation and adjustments, but what we were able to do in the computer allowed us to create and validate the industry-leading aerodynamic design we were after," said Lindgren.

"From there, the truck was refined, tweaked and ultimately christened the T680," said Lindgren. "It was ready for hand assembly into working, real units for road testing and validation. The T680 was truly alive. As we watched it perform in testing, and watched customers inspect the design and driver comforts, we knew we had hit a home run. It's a truck that sets new standards in aerodynamics, comfort and performance. As designers and engineers, we couldn't be more proud."

Kenworth Truck Company is the manufacturer of The World's Best® heavy and medium duty trucks. Kenworth is an industry leader in providing fuel-saving technology solutions that help increase fuel efficiency and reduce emissions. The company's dedication to the green fleet includes aerodynamic trucks, compressed and liquefied natural gas trucks, and medium duty diesel-electric hybrids. Kenworth is the only truck manufacturer to receive the Environmental Protection Agency's Clean Air Excellence award in recognition of its environmentally friendly products. In addition, the fuel-efficient Kenworth T700 equipped with the low-emission PACCAR MX engine was named the 2011 Heavy Duty Commercial Truck of the Year by the American Truck Dealers. Kenworth is also the recipient of the 2011 J.D. Power and Associates award for Highest in Customer Satisfaction for Heavy Duty Truck Dealer Service. Kenworth's Internet home page is at www.kenworth.com. Kenworth. A PACCAR Company.