Bosch Develops Integrated Rigid E-Axle for Heavy Commercial Trucks

Bosch has developed a rigid e-axle that integrates the electric motor and transmission for commercial vehicles, aiming to reduce weight and improve efficiency in heavy-duty electric trucks.

What Happened

The new axle is designed for vehicles weighing between 18 and 49 metric tons, a range that encompasses rigid distribution trucks up to tractor-trailer combinations. By mounting the drive unit directly at the axle, the system eliminates the need for a propshaft running back from a centrally mounted motor and gearbox. Bosch states that this configuration cuts vehicle weight and operates more efficiently than conventional electric center drives. The company notes that rigid e-axles and center drives compete in the heavy truck market, with each offering distinct trade-offs regarding packaging, driveline losses, and the ability to carry over existing chassis architectures.

Why It Matters

The integration of silicon carbide inverters, which Bosch rates at up to 99% efficiency, is central to the system's performance claims. These inverters use silicon carbide MOSFETs that switch with lower losses than traditional silicon IGBTs, reducing energy dissipation as heat. Additionally, Bosch developed a high-voltage blower module specifically for 800 V architectures in electric commercial vehicles and off-highway machines. This module manages cooling for key components on demand rather than continuously, addressing the parasitic load that cooling fans place on battery range in electric trucks. Higher bus voltages in these architectures allow for lower current, which reduces the size requirements for cables and connectors in auxiliary circuits. According to Bosch, these features collectively lower operating costs in freight transport.

The Bottom Line

Bosch’s new rigid e-axle offers a compact, integrated drivetrain solution for heavy electric trucks, leveraging silicon carbide technology and 800 V auxiliary systems to enhance efficiency and range.