Sigma Says Gearboxes Can Shrink EV Truck Battery Needs
Sigma Powertrain is making the case for purpose-built multi-speed gearboxes in heavy-duty EVs, saying they can improve efficiency and gradeability.
Sigma Makes the Case for EV Truck Transmissions
Sigma Powertrain is challenging one of the simplest assumptions in electric vehicles: that electric motors do not need transmissions. Founder and CEO John Kimes told Heavy Duty Trucking that the logic changes once trucks get heavier, duty cycles get tougher, and battery size becomes a fleet economics problem.
The company's pitch is that a purpose-built multi-speed gearbox can let heavy-duty battery-electric trucks use smaller motors, improve gradeability, and reduce battery-pack pressure. Kimes said the setup can improve efficiency by 10% to 15% in commercial EV applications.
Smaller Motors, Harder Jobs
In one example cited by the company, a 1,200-kW motor was replaced with an 800-kW motor paired with a Sigma transmission while still improving acceleration, gradeability, and overall efficiency. That is the kind of tradeoff fleets will care about if it lowers vehicle cost, preserves route capability, or reduces charging requirements.
Sigma currently offers three transmission families: MID-Series for Class 1-7 trucks, EMAX for Class 6-8 vocational applications, and Terramax for mining, drilling, and off-highway equipment. The largest Terramax configuration scales to 2.6 megawatts for 400-ton mining trucks.
Why It Matters for Fleet Spec'ing
The fleet question is straightforward: can EV trucks carry the same work without simply adding battery mass and cost? If drivetrain changes can improve efficiency in vocational and heavy-duty cycles, they may become part of how fleets spec electric trucks for routes where hills, payload, and stop-start work are unavoidable.
