The Mercedes-Benz powertrain plants in Germany are starting production of key components for the battery-powered eActros.
They include the electric axle and the battery packs, which are produced and assembled at the plants in Gaggenau, Kassel and Mannheim. These components will be used for the series production of the eActros, which will begin at the Mercedes-Benz plant in Wörth on 7 October 2021.
The technological heart of the eActros is its drive unit, which consists of a rigid electric axle with two integrated electric motors and a two-speed transmission. This concept has numerous advantages over designs involving a central motor. For example, the more compact design ensures that there is more space for the installation of additional battery capacity, which, in turn, has a positive impact on the vehicle’s range. Because of its direct power transmission, the concept is also more efficient than one with a central motor. The two motors provide impressive ride comfort and great driving dynamics. Moreover, the quiet and emission-free electric drive system is suitable for night-time delivery operations and also enables the truck to enter inner cities from which diesel vehicles are banned.
Depending on the version, the eActros gets its energy from either three or four battery packs and can achieve a range of up to 400 kilometres. The eActros can be charged with up to 160 kW. At a conventional DC fast charging station with a charging current of 400A, the three battery packs take a bit more than one hour to charge from 20 percent of capacity to 80 percent. With respect to availability and performance, the eActros is thus ideally suited for daily distribution operations.
Battery packs from the Mercedes-Benz plant in Mannheim
The Competence Centre for Emission-free Mobility (KEM) in Mannheim assembles individual battery modules into complete packs, which it then subjects to a function test. A battery pack for a series-produced eActros consists of six individual battery modules. A completely assembled pack is almost 2.20 metres long, 75 cm wide and 55 cm high. But before the modules become part of an operational pack, they are first installed into a metal housing and then connected to other components such as busbars, control systems and wires. They are then wired to the high-voltage cable sets, after which insulation layers that meet the highest safety standards are applied. In the final step, the electric/electronic box (E/E box) is attached to the pre-assembled metal housing, which will later form the interface between the battery and the vehicle. The E/E box is also pre-assembled at the Mercedes-Benz plant in Mannheim. After a final function and leakage test of the entire battery pack, the component is shipped to the Mercedes-Benz plant in Wörth.
The electric axle: A major role for the Mercedes-Benz plant in Kassel
The Mercedes-Benz plant in Kassel assembles the complete electric axle, consisting of the axle bridge, the electric motor and the shiftable transmission elements. The core axle is pre-assembled first. Among other things, this involves attaching the wheel hubs and the brake disks to the axle bridge. The drive unit, including the two-speed transmission, is pre-assembled in parallel. The Mercedes-Benz plant in Gaggenau supplies the transmission components for this step. After the core axle is pre-assembled, the entire drive unit, including the two-stage transmission, is “married” (attached) to the axle. Before the electric axle is prepared for shipment, it is subjected to a function and high-voltage test. These tests especially examine electrical safety and noise properties.
The electric axle is mounted on the same basis as its conventional counterpart. As a result, it is possible to integrate the manufacturing and assembly processes of the electric axle into existing production lines in parallel with the conventional production series. This makes the production process extremely flexible and cost efficient. During the integration of the electric axle, the main focus was on the commissioning of machines that were either adapted to the production of electric axles or newly purchased for them. This equipment includes machines for the pre-assembly of the drive unit, the final assembly of the electric axle and the entire test procedure.
Transmission-related components for the electric axle from the Mercedes-Benz plant in Gaggenau
The Mercedes-Benz plant in Gaggenau uses cutting-edge manufacturing techniques to produce transmission-related mechanical components and the associated housings. The main challenge here is that the transmission parts and the steel and aluminium housing components have to be made as precisely as possible because they are specified to extremely tight tolerances. This is necessary in order to ensure the electric axle works perfectly and has optimal noise properties. The range of components produced at the Mercedes-Benz plant in Gaggenau extends from a tiny planetary gear with an outside diameter of 57 mm to a drive wheel with an outside diameter of 365 mm and a raw component weight of over 40 kg. A total of ten transmission parts and three housing components are supplied to the Mercedes-Benz plant in Kassel, where the further assembly steps of the electric axle take place.