Allison Transmission and Cummins have received approval from the California Air Resources Board (CARB) to sell the Allison H 40/50 EP hybrid propulsion system paired with Cummins ISB6.7 and ISL9 diesel-electric hybrid engines for transit buses and coaches.
Allison says the system, which is used for both straight and articulated transit buses, has been shown to improve fuel economy up to 25% over similar diesel buses. Additionally, its regenerative braking capability can extend brake-change intervals by as much as 350%.
The ISB6.7 diesel-electric hybrid engine is rated at 280 hp (209 kW), while the ISL9 is rated at 330 hp (246 kW) for the transit bus market. CARB's order is valid for 2014 models, and the companies say they will also apply for approval of 2015 models.
Allison notes that it has delivered over 6,500 hybrid propulsion systems since 2003.