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Until recently, U.S. government efforts to dramatically reduce emissions, greenhouse gases and vehicle fuel consumption have primarily focused on passenger car applications. Similar aggressive reductions need to be extended to heavy vehicles such as delivery trucks, buses, and motorhomes. However, the wide range of torques, speeds, and powers that such vehicles must operate under makes it difficult for any current powertrain system to provide the desired improvements in emissions and fuel economy. Hybrid electric powertrains provide the most promising, near-term technology that can satisfy these requirements. This paper highlights the configuration and benefits of a hybrid electric powertrain capable of operating in either a parallel or series mode. It describes the hybrid electric components in the system, including the electric motors, power electronics and batteries.

This paper presents a discussion on manual transmission torque losses and focuses specifically on the relationship between torque loss, input speed and torque. It also includes a discussion on other factors affecting torque loss, such as inclination angle and lube oil temperature. Manual transmissions used in compact light truck applications have torque losses that are a function of input speed and torque. Efficiency studies done on manual transmissions in the engine-driving mode indicate that torque losses, in other than direct-drive gears, are considerably more dependent on input torque than input speed. It was also observed that efficiency was significantly affected by the inclination angle and lube oil temperature.