A drive system with a central longitudinal axis includes a brushless DC servomotor with a stator and a rotor disposed radially interior of the stator. The rotor defines a coaxial central void space. A planetary gear assembly connected to an input shaft and an output shaft is coaxially disposed in the central void space. A flange fixed to the rotor transfers torque to the input shaft. The ratio of the overall length of the drive system to its outer diameter is about one or less, thereby creating a power density along the central longitudinal axis that is greater than known electric motor/gear box drive systems.