Allison Transmission, the global provider of commercial duty automatic transmissions and hybrid propulsion systems, has been working to enhance the value of engines that run on compressed natural gas.
“(Allison Transmission is) an enabler for use with CNG engines in several commercial vehicle applications,” said Lawrence A. Love, executive director of Allison International Marketing.
“Unlike a diesel engine, CNG engines have different operating characteristics and are not as responsive during launch. Allison torque converter technology aids the CNG engine during vehicle start-up by multiplying engine torque and smoothly delivering power to the drive wheels,” said Love. “As a result, with an Allison (transmission), the vehicle gets good performance and makes the most efficient use of fuel.”
He added that most CNG engines are not capable of using an exhaust brake or delivering the same level of engine braking capability as a diesel. “However, the Allison transmission output retarder compensates for this by providing seamless auxiliary braking to improve overall vehicle braking capability and reduce service brake wear.”
The appeal of an alternative fuel source that burns 90 percent cleaner than diesel, and is also less costly, has convinced operators around the world in the past year to acquire Allison-equipped CNG vehicles. The inherent benefits of an Allison fully automatic transmission, including improved start-ability, more power to the wheels and better engine response have caused them to specify Allison.
In the USA, where Allison has been at the forefront of natural gas-fuelled vehicles from the outset, the company has earned further significant new partnerships with OEMs to make its fully automatic transmissions available for a wide range of applications.
Allison is facilitating the introduction of its transmissions to new CNG fleets across the country. Freightliner Trucks has equipped its liquefied natural gas/compressed natural gas (LNG/CNG) Business Class M2-112 tractor, the LNG/CNG M2-112 straight truck, favored by municipal and other vocational applications, and its MT45/55 step van with Allison transmissions for delivery applications.
At San Diego International Airport, Hertz Rental Bus has taken delivery of 17 CNG replacement buses - half of its bus fleet - using the B300 transmission.
This is in line with the practice of many other fleets in California where incentive funding is accelerating the replacement of old vehicles with newer, lower-emitting diesel or natural gas alternatives. In the ports of Long Beach and Los Angeles alone, there are now more than 600 Allison-equipped clean air trucks.
