Optimum impact for Benz
Heavy hauler adds major fuelsaving gear — in the axles
THE next generation Actros has been released in Europe but Mercedes-Benz Australia is still carrying out changes to the old model.
Given the new truck isn’t due here for at least another two years, it makes sense for Mercedes to improve its current heavy hauler.
Mercedes will develop new versions of the Actros, delivering fuel savings of 7-10 per cent over the existing model— a huge improvement. In one of the rare cases where the truck’s name actually makes a lot of sense, it calls these models Optimised.
The fuel savings come down mostly to new hypoid axles. Axle talk might make your eyes glaze over but they can make a huge difference in a big truck’s fuel efficiency.
Hypoid axles are not a new invention but they are new for the Actros. Most trucks run hub reduction axles, which means much of the torque multiplication happens in the hub. In the case of a hypoid axle, the effect takes place in the differential housing, inboard of the hub.
Hypoid axles are 41kg lighter, increasing the truck’s payload slightly (by 82kg in this configuration) and have superior mechanical efficiency, meaning more of the energy makes it all the way through to the wheels.
Mercedes says the change also affects the driving dynamics because of the more direct power delivery— it doesn’t need planetary gears.
To test the maker’s claim, Working Wheels headed to the Linfox-owned test track at Anglesea, Victoria.
Mercedes had prepared two prime movers, an Actros 2660 LS 6x4 with regular hub reduction axles and the equivalent Optimised model.
We drove each truck with a single trailer, with a combined weight of 40 tonnes, and in a B-double with 58 tonnes.
There is a sense of deja vu when you jump between the identical cabs— this is no bad thing as the Actros has neat- looking cabin, with easy to operate controls all within reach. It doesn’t look anywhere near as good or as modern as the next generation Actros, a moot point for now.
The trucks use the secondgeneration Powershift, an automated transmission with no clutch pedal.
The existing truck ran a 16-speed version of this transmission, which is still used for the heavy hauling version that retains hub reduction axles. The Optimised Actros models use a 12-speeder.
Mercedes says that while it has fewer ratios gears, the transmission is well suited to highway hauling, adding that the potent V8 sitting below the driver means it can work well with less.
Our test truck is running the 447kW (600hp) 15.8-litre V8. The Optimised Actros runs the 11.9-litre V6 with 328kW (440hp) or 357kW (480hp) or V8s producing 380kW (510hp) or 410kW (550hp).
The regular and Optimised Actros get up to speed quickly around the oval test loop and feel very similar. I get an indication the Optimised models feels slightly more nimble and seems to roll easier but I could just be imagining it.
Our 30-minute back-to-back fuel test is too short to be definitive but it indicates savings of up to 10 per cent for the Optimised hypoid axle models.
Mercedes has had Optimised trucks in test fleets covering hundreds of thousands of kilometres and showing similar improvements. It says that in one operator fleet test held over 280,000km, an Optimised Actros used $28,140 less fuel than similar American trucks doing the same job over the same route.
Better believe the hype: Fitted with lighter, more efficient hypoid axles, the Actros makes fuel savings of up to 10 per cent