Overdrive Magazine | Trucking Business News & Owner Operator Info
Issue link: https://read.dmtmag.com/i/455137
February 2015 | Overdrive | 37 created in two ways. One is when any shape on a truck that isn't smooth – such as rearview mirrors and bug screens – impedes airflow around the vehicle. Drag also is created by a vacuum – a low-pressure area that sucks in air that ideally would flow smoothly past the vehicle – that creates turbulence. Bumper-mounted air dams and trailer side skirts and tails all help improve airflow underneath and around tractor-trailers. Trailer tails and side skirts also can reduce aerody- namic drag and help stabil- ity in crosswinds. The tail reduces the drag created by the vacuum at the back of a fast-moving tractor- trailer, while skirts mini- mize the drag produced by the swirling of air under the trailer. Undercarriage fairings work on the drag at the trailer's rear, with a pri- mary component installed ahead of the trailer axle to deflect air down and away from the axle plumbing. The trailer gap area, which often is cited as a large component of tractor- trailer drag, is more chal- lenging, says Mike Hen- derson, chief scientist for SmartTruck. Low pressure in the gap reacts on the tractor's rear and its fairing and the trailer's front. The solution, Henderson says, is to place fairings on the front of the trailer's top and sides; the larger the gap, the larger the trailer fairings needed. More aero solutions Other aero solutions that can help improve fuel economy, according to experts, include: A lower sleeper roof. In liquid bulk and flatbed operations, loads are unlikely to rise above the midroof setup's height. For some high-density-load haulers, a flattop may be a better choice. Rounder mirror backs. Try these instead of old-style flat West Coast mirrors for the side views. Tanks with aero steps. Fuel tank fairings can be paired with steps to help smooth airflow over the tractor's lower side. Wheel hub covers. Outfit all outside-facing wheels with them to help smooth airflow across the wheels. Cab side extenders. For tractors not already optimized for aerodynamics, these can create a smoother airflow over the tractor- trailer gap. Nose cone fairing. For flattop or midroof tractors pulling dry vans, these devices combine the vertical fairing of more standard tractor-trailer gap technology with an outsize fairing at the top. Air tabs. Recommended locations for these small tabs or blades are on the hood, along the sides and at the top rear of the tractor and/or trailer. Each one is designed to create air swirls that combine to help reduce suction and drag at highway speeds. Aero mudflaps. When using wide-single tires in drive and trailer positions, combine porous mudflaps with specially designed brackets that eliminate the overhang of conventional mudflaps. Undertray system SmartTruck says its UnderTray systems can produce fuel sav- ings of more than 6 percent. The company's UT6-Plus system includes an undertray, a rear air diffusor, two fairings on the truck's rear and a roof fairing. SmartTruck Systems, smarttrucksystems.com Vortex generators VorBlade's small vortex generator blades are wishbone- shaped airfoils that smooth airflow over a truck's trailing edges on the back of a cab or trailer. VorBlade Products, vorblade.com Trailer aero device ATDynamics' TrailerTail Trident 3x3 is a three-sided 3-foot- long aero device designed to reduce semi-trailer suction drag and provide about 90 percent of the fuel savings benefit of the company's longer 4x4 version, which has an additional lower panel section. ATDynamics, atdynamics.com