Truck operators could improve their fuel economy by as much as 8 percent by facilitating smooth air flow around their tractor-trailer units during highway travel, according to a new study by Mack Trucks Inc.

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.
“We are very excited about the results of our study,” said Mark Kachmarsky, Mack chief project manager-product range management. “Maximizing fuel economy is a key concern for our highway customers in particular. An 8 percent improvement would certainly have a dramatic impact on their bottom lines. In addition, reducing fuel use results in cleaner air.”
The space between a tractor and a trailer is traditionally a significant contributor to aerodynamic drag – which increases fuel use. The enclosure used in the Mack study to cover this gap consists of two sections of material – one attached to each side of the rear of the tractor – that extend back towards the trailer. The side skirts, which attach to the bottom edges of the trailer on both sides and run nearly its entire length, help minimize overall drag by preventing air flow from interacting with the underside of the trailer as well as the axles and wheels. The boat tail is another two-piece drag-reducing system that is affixed to the rear of the trailer.
Kachmarsky said that Mack 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.
Matching funds to conduct the research were provided by the United States Department of Energy (DOE) FreedomCAR and Vehicle Technologies Office through the National Energy Technology Laboratory. The Truck Manufacturers Association (TMA) coordinated the project, which involved a total of four of its members.
For more information about Mack, visit www.macktrucks.com.