Eaton announced its eMobility business has been chosen to supply a four-speed, medium-duty electrified vehicle (EV) transmission to Proterra for the company’s ProDrive drivetrain used in Proterra ZX5 electric transit buses.

“Our EV transmissions have unmatched performance, providing class-leading acceleration, horsepower, range and durability,” said Julie Marshaus, manager, New Product Introductions, ePowertrain. “The transmissions also have the ability to enable longer range due to efficiency gains.”

The medium-duty, four-speed transmission is a lightweight, countershaft gearbox that enables manufacturers to use more efficient motors.

Eaton’s four-speed transmission has helical gears with a shifting strategy designed to extend range and battery life. Road tests have shown a 20%­ to 30% efficiency improvement in energy consumption under normal driving conditions compared with a direct-drive transmission and a 10% to 15% improvement compared with a current two-speed solution.

“Eaton has been in the hybrid transmission business for over 15 years, and we have more than two billion miles of reliable operation of hybrid transmission-equipped trucks and buses on the road,” Marshaus said. “Our four-speed transmission provides uncompromised launch-ability on grade and has shift points to keep the electric motor operating in its most efficient region while drivability and vehicle safety is taken into account.”