Overdrive Magazine | Trucking Business News & Owner Operator Info
Issue link: http://read.dmtmag.com/i/93143
Drag increases exponentially with speed. "Even with all available aero- dynamic gains, a sharp increase in road speed can easily negate any net fuel economy gains," McKenna says. "Our research shows that an aver- age road speed of 62 to 65 miles per hour with a full array of aerodynamic components at work is the best of both worlds in terms of productivity and fuel economy." One reason for the attention to trailer aerodynamics is that all com- ponents of a vehicle's design interact with each other. Optimizing the trac- tor, trailer and driver as a complete system of mutually supporting ele- ments is essential, says Rick Mihelic, manager of vehicle performance and engineering analysis for Peterbilt. "Enhancing synergy between leading-edge areas like the crown, windshield edges, mirrors and bum- per with downstream effects on the tractor and trailer will yield optimal performance gains," Mihelic says. "We're already seeing this in current designs as OEMs and third parties work to provide components that fur- ther integrate combination vehicles," says Frank Bio, product manager for Volvo Trucks. In redesigning a truck for optimum aerodynamics, Volvo looks at all exterior components and how they interact together – all the way to the trailer. "The entire truck works as a system, so a change to one component can affect how air flows around another," Bio says. It's hard to imagine a less aerody- namic structure than a 53-foot-long box with no rounded edges. Making mat- ters worse with a trailer's aerodynamics is the gap between it and the tractor, says T.J. Reed, director of product mar- keting for Freightliner Trucks. "Wind moving around even the most aerodynamic tractor gets sucked into this gap and creates a tremen- dous amount of turbulence and drag," Reed says. "Even crosswinds can add to the drag created in this (Continued on Page 67) California aero trailer mandate kicks in Jan. 1 The New Year will ring in a major requirement for owner-operators who haul in California. Small fleets of 20 or fewer trucks have until Jan. 1 to either outfit pre-2011 53-foot dry van and reefer trailers with SmartWay- certified aerodynamic devices that improve fuel economy between 4 and 5 percent, or register to delay meeting the requirement until 2016. SmartWay is a program of the U.S. Environmental Protection Agency. "The clock is ticking for compliance," says Randy Rhondeau of the California Air Resources Board. "Fleets and owner-oper- ators who travel into California must have aerodynamic devices unless they registered with CARB on a phase-in option" that pro- vides an alternate compliance schedule. "If you're pulled over for noncompliance, the owner of the tractor-trailer can be cited Aerodynamics can reduce a tractor- trailer's drag coefficient and improve fuel economy significantly, though not at speeds below 55 mph. $1,000 per day. The driver of the tractor- trailer is not off the hook, either – that person can be fined $1,000 a day as well." For repeat offenders, fines can increase to $10,000 per day. CARB adopted the regula- tion in 2008 to reduce greenhouse gas emissions. The goal is to improve fuel effi- ciency by using aerodynamic features and low rolling-resistance tires. For rigs with box-type trailers 53 feet or longer, 2011 van and reefer trailers already must meet the requirement. SmartWay-certified tires won't be required on pre-2011 box trailers until January 2017. CHECK THE RULES: See complete details on CARB regulations at arb.ca.gov. Search "tractor-trailer greenhouse gas regulation." Too wide a trailer gap is a fuel economy killer. Optimal distance between a trailer and the back of the cab is generally 30 inches with each 10-inch gap increase boosting vehicle drag by 2 percent. December 2012 | Overdrive | 33