FIGURE 5-8 Tractor-trailer combination truck showing aerodynamic losses and areas of energy-saving opportunities. Percent changes refer to fuel consumption. SOURCE: Based on Wood (2006). Courtesy of Richard Wood.

FIGURE 5-8 Tractor-trailer combination truck showing aerodynamic losses and areas of energy-saving opportunities. Percent changes refer to fuel consumption. SOURCE: Based on Wood (2006). Courtesy of Richard Wood.

“base” fairing, which are all illustrated in Figure 5-8, along with the approximate fuel consumption reductions that seem to be achievable in the near term.

Aerodynamics of the Truck Tractor

The contemporary image of aerodynamically optimized tractors is that of sleeper cab tractors equipped with many fairings, such as the SmartWay trucks shown in Figure 5-6 and the left-side image shown in Figure 5-9. These tractors are typically used in long-haul applications where the ability to provide “hotel” accommodations is important. However, many long-haul operators use a terminal-to-terminal system that does not require sleeper tractors. These operators use day cab tractors such as that shown on the right in Figure 5-9. Shorter-haul operators tend to avoid aerodynamic fairings because they provide limited fuel savings and are prone to damage in urban operations and during frequent stops at loading docks. Day cab tractors often are equipped with only a roof fairing, and for nonvan applications they may carry no fairings at all. Day cab tractors make up about one-third of all tractor sales, and so they are a significant portion of the market.

Most tractor manufacturers introduced tractor offerings in the 2003 to 2008 period that included purposeful, major improvements in their aerodynamic performance accomplished by attention to many details and utilizing most of the evaluation tools noted earlier. Reports of fuel consumption reductions of up to 6 percent were received during committee site visits.

FIGURE 5-9 Volvo full sleeper cab (left) and day cab (right). SOURCE: Courtesy of Volvo.

FIGURE 5-9 Volvo full sleeper cab (left) and day cab (right). SOURCE: Courtesy of Volvo.



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