USA | Transmissions Pioneers in the Wild West of EVs: an interview with John Kimes of Sigma Powertrain By Bradley Osborne – 22nd August 2023 Sigma Powertrain's flagship product is the EMAX, an electric drive system for electric vehicles in classes 6-8, as well as offroad vehicles and heavy equipment. It incorporates a transmission based on a patented design which uses no hydraulics.