This was established by consumption measurements during practical test drives monitored and verified by TÜV SÜD Automotive.
Safety, braking performance and the protection of the service brake have top priority for fleet managers – this was demonstrated by the results of the customer satisfaction analysis in 2009. Equally high are the demands on a wear-free continuous braking system. In the overall satisfaction stakes, the Voith Retarder leads the field and is clearly ahead of the engine brake. Yet until recently, there was one critical aspect: it was assumed retarders have a negative impact on fuel efficiency. However, while discussions about extra fuel consumption crop up from time to time, commercial vehicle manufacturers and haulage operators keep pointing out that technology-induced higher consumption is compensated in everyday operation by adapted driving, which might even lead to a drop in fuel consumption.
Preliminary tests by Voith Turbo have confirmed this hypothesis already on several occasions and provided the initiative for a recent series of test measurements with TÜV SÜD Automotive, the independent technical inspection association of the German automotive and automotive suppliers industry. The route for this driving test led through the area of Trier, on Autobahns A1 and A62 between Wittlich and Kusel. The stretch, which is frequently used for tests by journalists and commercial vehicle manufacturers, measures approximately 185 kilometers, with altitude differences of 140 to 560 meters.
The test design: eight impartial professional truck drivers and two professional instructors steered the test vehicles. Each driver took the route three times with two vehicles – with and without retarder. In tests without retarder, the unit weight and the different body weights of the drivers were compensated by relevant load additions. In total, 99 trips were evaluated (49 with retarder and 50 without), with the fuel consumption being determined after each trip via mass differentiation measurements. For this purpose, the tank was completely drained, the remaining fuel was reweighed in a separate container and the measuring values, as well as weather and temperature conditions and special route features, were documented.
The evaluation of the data showed that the retarder in combination with an automated transmission leads to a fuel reduction of approximately 0.3 kg/100 km, which corresponds to 0.33 liters of diesel per 100 kilometers. At a mileage of 180 000 km per year, this corresponds to a saving of some 594 liters and approximately EUR 612 (diesel price EUR 1.03/l) per year. With automated transmissions, the savings effect is higher than in combination with manual transmission. This is also manifested by the trend towards automated transmissions at Mercedes-Benz, where the PowerShift transmission is already offered as a standard fitment. Yet the most important influential factor is the driver. Depending on how he handles the vehicles, up to 12 percent fuel can be saved. The reasons behind this saving with the Voith Retarder are driving with foresight, more even speed profiles, lower medium engine speeds and fewer gear shiftinges.
If one adds the cost for a complete brake replacement of an articulated truck (brake pads/discs) of EUR 2 600 and just one brake replacement for the trailer (brake pads) of EUR 1 115 to the fuel savings of EUR 612, the purchase of a Voith Retarder already pays off during the first year.
Voith Turbo (voithturbo.com), the specialist for hydrodynamic drive, coupling and braking systems for road, rail and industrial applications, as well as for ship propulsion systems, is a Group Division of Voith AG.
Voith (voith.com) is setting the standard in the paper, energy, mobility, and service markets. Established on January 1, 1867, Voith is now one of the largest family-owned businesses in Europe, with 43 000 employees, 4.9 billion euro in sales, and over 290 locations worldwide. Voith is an official partner of the initiative "Germany – Land of Ideas".