CARB Certifies Allison – Cummins Hybrid Electric Powertrain


Allison Transmission Holdings Inc. and Cummins Inc. have received annual certification from the California Air Resources Board (CARB) for the model-year 2021 Allison Hybrid 40/50 Electric Propulsion (H 40/50 EP) system paired with the Cummins B6.7 and L9 diesel-electric hybrid engines.

Originally issued by the CARB in 2014, the dual executive order is required to be reviewed for renewed eligibility on a model year basis. The Allison electric hybrid propulsion system and Cummins engine pairing is used in both straight and articulated transit buses, as well as coaches.

In full operation since 2003, the Allison H 40/50 EP has been proven to reduce emissions, ensure quieter operation and improve fuel economy up to 25% over similar diesel buses. Allison says it provides fast acceleration for an overall smoother ride. Additionally, the H 40/50 EP’s regenerative braking system converts the vehicle’s kinetic energy to stored electric energy when decelerating or stopping. This capability can significantly extend the brake change interval by as much as 350%, reducing maintenance costs.

“We appreciate CARB’s continued renewal,” says Barbara Chance, director of mobile source regulatory compliance for Allison Transmission. “Allison was the first electric hybrid propulsion system to be certified in California for transit buses and coaches. We are particularly excited to now turn our collaborative focus with CARB on 2022 certification of our eGen Flex electric hybrid propulsion solution, which provides full EV capability for up to 10 miles.”

The Cummins B6.7 and L9 diesel-electric hybrid engines feature proven technology designed and developed in-house that is optimized to deliver the efficiency, durability and performance. The B6.7 diesel-electric hybrid engine is rated at 280 hp (209 kW) while the L9 diesel-electric hybrid engine is rated at 330 hp (246 kW) for the transit bus market.

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