Allison is a Leader in Developing Automatic Transmissions for CNG Buses

Allison Transmission, Inc., the world's leading supplier of commercial duty fully automatic transmissions and hybrid propulsion systems, is also a leading supplier of automatic transmissions for compressed natural gas-powered (CNG) buses. Allison has been a leader in developing automatic transmissions for city transit buses for more than 60 years, engineering products for diesel, hybrid and CNG applications to meet a growing worldwide demand for affordable, efficient mass transit.

That leadership continues today with cities all over the world adding CNG-powered buses to their public transportation fleets. Not only does this alternative fuel source burn 90 percent cleaner than diesel fuel, it is also less costly, which is a significant concern as the price of diesel continues to spiral upward.

"An Allison automatic transmission is an enabler for use of CNG engines in city bus applications," says 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. As a result, with an Allison, the bus gets good performance and makes the most efficient use of fuel, which is vital in an era of rising fuel costs."

"In addition, most CNG engines are not capable of using an exhaust brake or delivering the same level of engine braking capability as a diesel," says Love. "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."

Earlier this year, TATA Motors in India purchased 655 CNG-powered buses configured with Allison automatics for Delhi Transport Corporation. Drivers and passengers alike are raving about the smooth, comfortable ride, while DTC fleet managers enjoy lower maintenance and operational costs because there is less wear and tear on critical engine and driveline components.

In addition to this contract win in India, Allison Transmission is the number one provider of automatic transmissions for CNG- and conventional-powered buses in China.

During the 2008 Summer Olympics last month in Beijing, China, for example, a team of Allison experts were on hand to make sure that the 12,000 Allison transmissions in service in Beijing continued to operate faithfully. Many of these buses are equipped with CNG engines. Allison employees established a command center bringing in a support team and replacement parts, and manned a sophisticated logistics and communications program in support of the games.

Across the United States, the environmental benefits of Allison automatics mated with CNG engines are recognized. Used primarily on the west coast because of stringent emission laws, CNG buses with Allison transmissions are operating in large cities such as Los Angeles and San Diego, California, and Las Vegas, Nevada. In fact, CNG engines are specified almost exclusively in Los Angeles. Notably, the majority of the North American bus OEMs offer the Allison/CNG combination.

In addition to India, China, and the U.S., CNG-powered city transit buses equipped with Allison transmissions are now in use in many other countries around the world including Japan, Russia, Peru and Australia.

"The environmental benefits of CNG buses in terms of lower emissions and cleaner air are clear," says Manlio Alvaro, Allison Marketing Manager for Europe. "Equally clear is that mating those buses with Allison transmissions means a smoother launch and ride for passengers, and longer operational time and lower maintenance costs for bus fleet operators."

Allison Transmission, Inc. (Allison) headquartered in Indianapolis, Indiana employs 3,600 people and was founded in 1915. Allison is the premier global provider of commercial and military duty automatic transmissions and hybrid propulsion systems. More information is available at http://www.allisontransmission.com.