Trucks
Trucks
How do you increase battery capacity on an electric truck without sacrificing too much payload? By developing a unique lightweight tag axle, Volvo Trucks can offer the payload of a 6x2 with the functionality of a 4x2 – and enough range for long-haul transport.
With the launch of Volvo Trucks’ new electric range, one of the most noticeable features on some models is the addition of a smaller tag axle behind the drive axle. While unconventional in design, this unique innovative solution has enabled us to develop an electric 4x2 tractor that can not only cover ranges of up to 600km but also offer loading capacity of up to 28 tonnes.[1]
Overall, 4x2 tractors are more sensitive to weight due to the restrictions that can be applied to the rear drive axle and fifth wheel. This creates an added layer of complexity when it comes to electrification and weight distribution.
With the addition of an e-axle to our latest electric models, we can now install up to eight batteries, which in turn means ranges of up to 600 km. However, for many electric 4x2 trucks on the market, the additional batteries can reduce payload to around 20-22 tonnes – compared to 24-26 tonnes for a typical 4x2 diesel tractor.
There is also the issue of diminishing load. Even if a fully loaded 4x2 is within legal limits, the center of gravity can shift onto the drive axle as it is unloaded, quickly overloading the fifth wheel. This requires frequent repositioning of the load or accepting even lower loading capacity. In fact, sensitivity to weight distribution can reduce loading capacity of an electric 4x2 for long-haul transport to as low as 16-17 tonnes. This leaves truck owners who may be keen to switch to electric having to make a tradeoff between payload and range – something we wanted to avoid when developing the lightweight tag axle.
By adding a lightweight tag axle to an electric truck, the load capacity can be increased to similar levels as a conventional diesel truck.
Much like the additional axle on a conventional 6x2 tractor, the lightweight tag axle relieves weight from the drive axle and fifth wheel and increases the overall load capacity to similar levels as that of a conventional diesel 4x2 (approximately 24 tonnes in the EU, 28 tonnes in Scandinavia). It is also around 300 kg lighter than a conventional axle, which corresponds to a similar gain in payload compared to a 6x2 tractor.
In addition, the lightweight tag axle provides greater flexibility in load distribution. It has the same loading capacity regardless of where the load is positioned, giving operators the same freedom to unload as with a conventional diesel truck.
While the addition of a lightweight tag axle technically makes the configuration a 6x2, it is important to stress that it still delivers the same functionality and benefits as a 4x2.
Due to the reduced diameter of the tag axle’s wheels, the fifth wheel is in practically the same position, height and inclination as a standard 4x2. This ensures that the vehicle can use standard trailers without increasing the overall height of the combination or significantly increasing the cab-trailer gap. For example, when fitted with a standard trailer, the truck will be still under the height limits for the Elbtunnel in Hamburg – unlike a standard 6x2.
The lightweight tag axle is available as both fixed and steerable. With a steerable tag axle, the eight-battery model provides the same turning radius as a conventional long-haul 4x2 while the shorter, six-battery model offers an improved turning radius and by extension enhanced maneuverability and agility.
In short, the lightweight tag axle enables us to develop an electric 4x2 truck that can deliver both the required range and payload for long-haul applications.
Learn more about Volvo Trucks’ latest electric range
[1] Exact loading capacity is dependent on local regulations on gross combination weight. In markets where the maximum allowed GCW is 42 tonnes (40 tonnes plus additional two tonnes for zero emissions vehicles) the loading capacity for a Volvo FH Aero Electric with standard ISO trailer is up to 22 tonnes. If the maximum GCW is 46 tonnes, the loading capacity is up to 26 tonnes. In markets where the maximum allowed GCW is 48 tonnes or over, the loading capacity can be up to 28 tonnes.
