Volvo, Mack demonstrate aerodynamic truck technology

WASHINGTON, D.C. — Some simple modifications to heavy truck aerodynamics could provide a welcome decrease in fuel costs for the average over-the-road truck, says truckmakers Volvo and Mack.

The two companies were among OEMs demonstrating the performance of all new aerodynamic features for Department of Energy officials in Washington this week.

Volvo showed a 2.3 percent improvement in fuel economy through the use of four modifications to a typical highway tractor and trailer. Three of the modifications are prototype designs, while the fourth is already available on Volvo trucks.

The company says it addressed improving airflow under the vehicle and reducing the interaction between the underside and the gap between the back of the tractor and the trailer. Controlling airflow on the underside of tractor-trailer combinations, says Volvo, can reduce the amount of turbulence and aerodynamic drag produced by a moving vehicle when air rushes by axles, wheels and other objects.

Three devices were used for underside airflow management, said Michael Sorrells, Volvo’s lead design engineer for aerodynamic development. The first was a smooth underside area on the front of its test truck, essentially an extension of the bumper made from composite material. The device did not need to extend back very far and would have little impact on the truck’s operation or maintenance.

Mack said that results of the recently completed two-year study of truck aerodynamics demonstrated that significant fuel savings can be achieved by enclosing the gap between the tractor and trailer, and equipping the trailer with what are referred to as “side skirts” and a “boat tail” to improve its aerodynamic profile while on the road.

Mack says engineers are already looking to generate an actual production gap enclosure based on the rough prototype used in the study. The company is also sharing the results of the project with trailer manufacturers who might consider incorporating side skirts and boat tails.

Another modification on Volvo’s trucks was a plate between the chassis rails on the space between the back of the cab and the fifth wheel, called a deck closure According to the company this prevents airflow under the tractor from rushing up into the trailer gap, which creates strong turbulence and aerodynamic drag.

The final change involved the use of roof and side fairing extenders already available. These extenders reduce the gap between the rear of the tractor and the front of the trailer. A smaller gap improves airflow, whereas a larger gap creates drag as the air gets trapped against the front wall of the trailer. The roof extender uses a Volvo-patented design so it can be adjusted to not only reduce the trailer gap, but to optimize aerodynamics when using trailers of different heights or with different kingpin settings.