“There’s a lot of fuel to be saved on trailers,” says Phil Braker, operations manager at Nussbaum Transportation in Hudson, Ill. That’s why the progressive company runs wide-base single tires, which led to its latest innovation, full-length skirts on its 53-foot-long, 102.3-inch-wide vans from Wabash National.
“We started on this a couple years ago during a visit with Wabash while they were here,” he recalls. “The single tires were inset enough from the sides so there’s clearance for a skirt alongside." Wabash thought they could work with that. More consultations led to the first prototype, which has been on the road for a year.
Each skirt has two top-hinged doors that swing up to allow access to wheels and tires for inspections and maintenance. The doors are at the tandem’s standard running position, or the tandem can be slid for access. They can be locked in the up position or pinned down for travel.
They’re the same material as DuraPlate AeroSkirts, a little thinner, with three stationary, vertical, stainless steel posts to keep them away from the wheels, plus tether straps to retain a door in case of a tire blowout.
“That was a worry of some drivers – ‘What’s going to happen if we blow a tire?’ But that hasn’t happened," Braker notes, adding that Meritor-PSI tire inflation systems help keep tire pressure up.
Wind tunnel testing showed a 4% aerodynamic improvement over a regular skirt. “We don’t quite get that, but it’s still worthwhile. There are now 101 trailers in service, and they seem to be working well.”
The latest version on the last 30 trailers also extends forward by 42 inches to cover the landing gear and beyond. The longer skirts add some weight and cost, but make up for it with better fuel economy. Braker figures the long skirts alone pick up 0.5 mpg.
The fleet’s trailer-to-tractor ratio is just over 2 to 1, making the aero improvers financially feasible. The longer skirts will probably go on all new trailers.