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For transmission suppliers tooled primarily for producing manual transmissions, retrofitting a manual transmission with actuators and a controller is business viable. It offers a low cost convenience for the consumer without losing fuel economy when compared to torque converter type automatics. For heavy duty truck fleets even the estimated 3% gain in fuel economy that the Automated Manual Transmission (AMT) offers over the manual transmission can result in lower operational costs. This paper provides a case study using a light duty transmission retrofitted with electric actuation for gears and the clutch. A high level description of the control algorithms and hardware is included. Clutch control is the most significant component of the AMT controller and it is addressed in detail during operations such as vehicle launch from rest, launch from coast and launch on grades.

A multi-mode hybrid hydromechanical transmission (HMT) with infinite variability is designed to meet the power transmission needs of medium duty on- and off-road vehicles. A hydraulic pump-motor assembly provides output speed and torque variability in an input coupled split power configuration. Dual planetary arrangements with two multiplate clutches allow multi-mode ratio change and combination of power from the mechanical and variable branches of the power path. Hydraulic accumulators offer hydraulic power assist during launch conditions and storage of reclaimed energy during braking events. Transmission kinematic, force and power flow analyses will be developed for the HMT and analyzed for suitability in a bus application. The resulting benefits and areas for improvement will be discussed.