Allison Transmission > Commercial Products > Hybrid Bus
Hybrid Bus - EP40/EP50
Allison is the world’s largest heavy-duty hybrid producer. There are over 2,600 buses and coaches equipped with the Allison Hybrid EP System™ currently operating in over 130 cities worldwide. These hybrid buses have provided over 100 million miles of reliable and low emission service.
The Allison Hybrid EP System™ can significantly enhance the performance of transit buses, suburban coaches and articulated buses operating in a variety of environments‚ whether it's stop-and-go city traffic, over-the-road or a combination of the two. The Allison Hybrid EP System™ bridges the gap between traditional mechanical engine propulsion systems and zero-emission technologies. Buses equipped with this system have significant improvement in fuel economy and significantly reduced emissions. They also have better acceleration than conventional diesel-powered buses. Not to mention quieter operation. The Allison Hybrid EP System™ features two-mode compound split parallel architecture with two paths‚ a pure mechanical path and pure electrical path‚ to achieve the highest energy efficiency. Two electrical motors combined with a very efficient mechanical path and energy storage provide efficient stop and go application as well as effective highway performance. The entire system is controlled by comprehensive energy management software. It offers the best of parallel hybrids and series hybrids in one system.
| Emissions reduced | With the Allison Hybrid EP System™, overall emissions are significantly reduced during operation compared to conventional combustion engines. Oxides of nitrogen (NOx) emissions are reduced up to 50%. The system also provides significant emission reduction when compared to alternative propulsion systems. |
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| Regenerative braking | When stopping or decelerating, vehicle energy is converted to electric energy and stored. In effect, the motor becomes a generator. 40% of the energy to accelerate the bus comes from the energy saved during regenerative braking. |
| Proven durability | The advanced Nickel Metal Hydride energy storage system has a six-year target life and no requirement for battery conditioning. In over 100 million in-service miles, the Allison Hybrid EP System™ has not had a single end-of-life battery cell failure. |
| Enhanced acceleration | A bus equipped with the Allison Hybrid EP System™ can significantly out-accelerate a similar bus equipped with a conventional drivetrain or an alternative fuel system. And the acceleration is seamless. |
| Improved fuel economy | The National Renewable Energy Laboratory (NREL) conducted chassis dynamometer tests using two 60' buses, one with the Allison Hybrid EP System™ and one with a conventional powertrain. The testing showed a 75% improvement in fuel economy during a stop and go Manhattan duty cycle. Actual in-service fuel economy improvements range from 20-54% compared to conventional buses. |
| Quiet Operation | The Allison Hybrid EP System™ helps reduce noise pollution compared to conventional buses. At 79 db at 10 meters, buses equipped with the system approach the sound level of passenger cars. |
The Allison Hybrid EP System™ is supported by over 1,500 authorized Allison Transmission distributors and dealers all over the world. That commitment includes the parts, service and in-depth expertise you have enjoyed for many years with Allison Transmission products in the bus and transportation industry.
It is our collective responsibility to make the earth a better place, and the Allison Hybrid EP System™ exemplifies our efforts to preserve and improve the quality of our environment. It's simply the right thing to do‚ for today and for future generations.