The fuel consumption of the Actros has been steadily reduced over the past decades. In typical long-distance transport operations, for example, savings of up to 15 percent have been achieved between 2011 and the introduction of the new Actros from 2019. The new Actros is even more economical than its predecessor on motorways by up to as much as three percent and in inter-city traffic by up to five percent. In addition to the optimised Predictive Powertrain Control (PPC) cruise control and transmission control system, new rear axle ratios and aerodynamic improvements to the truck’s cab make a major contribution to this reduction in consumption.
Aerodynamics as one of the most important levers for reducing consumption
The great importance of aerodynamics can be illustrated by a number: in a modern cab-over-engine truck in European long-distance operations, around one third of the available mechanical energy is needed to overcome the air resistance. And this is also reflected in the new Actros: the MirrorCam alone, which replaces the traditional rear-view mirrors, contributes as much as 1.5 percent to the overall fuel savings of the new Actros. New concave cab side deflectors on the cab also make a contribution towards lowering the consumption.
A complex system: axial blower for wind speeds of up to 250 km/h
These improvements are due not least to intensive testing in the wind tunnel at Daimler AG’s Untertürkheim plant. There, the engineers simulated the flow conditions around the truck with the aim of optimising the Cd value for wind slip, and thus in turn also the fuel consumption. Especially with regard to the MirrorCam, the tests in the plant provided valuable information. On the one hand for the aerodynamic design of the two camera arms and on the other for the positioning of the camera arms on the right and left-hand sides of the cab. Unlike conventional mirrors, these are fixed to the roof frame in the new Actros.
The wind tunnel in Untertürkheim enables the developers to generate wind speeds of up to 250 kilometres per hour. “Here, in parallel to computer-based flow calculations – i.e. digital simulations using computational fluid dynamics (CFD) – random spot checks were carried out to confirm the aerodynamic improvement of conceptual components,” says Michael Hilgers, Head of CAE Vehicle Functions in Commercial Vehicle Development at Mercedes-Benz. In addition, the aerodynamic measurements are validated during on-the-road testing. The engineers thus benefit from having several powerful methods at their disposal simultaneously, which can be used to make Mercedes-Benz trucks as aerodynamic as possible.
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