An electromechanical gear is presented along with design examples utilizing the electromechanical gear in hybrid electric vehicle drive trains. The designs feature the electromechanical gear (the Transmotor) in place of traditional mechanical transmissions and/or gearing mechanisms. The transmotor is an electric motor suspended by its shafts, in which both the stator and the rotor are allowed to rotate freely. The motor thus can provide positive or negative rotational energy to its shafts by either consuming or generating electrical energy.A design example is included in which the transmotor is installed on the output shaft of an internal combustion engine. In this arrangement the transmotor can either increase or decrease shaft speed by applying or generating electrical power, allowing the ICE to operate with a constant speed. A torque splitting device is then employed to absorb excess torque produced by the engine or to create supplementary torque when needed, allowing the ICE to operate with constant torque. Thus a constant speed constant torque engine can be directly coupled to the output drive shaft by using electric machines.The governing equations, a control strategy and an analysis corresponding to each operating mode of the architecture are presented. The operating regions and boundaries of individual components are investigated and engine, motor and energy storage system sizing are identified.