Eaton, once a supplier of two-speed rear differentials for trucks, has developed a two-speed transmission for heavy- and medium-duty electric commercial vehicle applications to meet growing demand in Europe and other markets. The product will be in full production this autumn.

Eaton has partnered with UQM Technologies, based in Longmont, Colorado, and Pi Innovo, based in Plymouth, Michigan, to design and produce the UQM PowerPhaseDT system. Eaton has developed and will supply to UQM a two-speed transmission for an electric vehicle application, and Pi Innovo will develop and supply to UQM the transmission control unit. Together, the components will be combined with UQM's current PowerPhase HD220/HD250 motor and inverter system to create the UQM PowerPhase DT, which is a full electric drive system.

The system will allow customers in the medium- and heavy-duty EV commercial markets to achieve increased performance in areas of grade performance, acceleration and efficiency. Eaton's two-speed transmission provides a greater speed and torque range which allows a smaller electric motor to power large vehicles. The smaller drivetrain also allows for improved packaging efficiency, greater payload capacity, and lower cost when compared with direct drive or single speed drivetrain strategies.

In addition, the two-speed transmission keeps the electric motor operating in the highest efficiency region for a greater portion of the drive cycle. Combined with the high efficiency of the electric drive system, customers will achieve higher overall vehicle efficiency, save on the cost of batteries, and increase the driving range of their vehicles.

The development and production of a full electric drive system supports the overarching need for full transmission systems, as enhanced performance and efficiency requirements are mandated by customer drive cycle needs coupled with the need to reduce battery costs while meeting more stringent regulatory requirements.