A dual function gearbox generates two separate output rotational motions from a single input rotational motion. First and second rotatable housings comprise corresponding first and second internal gears, with the internal gears having different pitch diameters. A drive shaft is disposed within the housings, extending though openings within opposite sides of housings, with an eccentric rotor disposed around the drive shaft. The eccentric rotor is in operative contact with a differential gear ring comprising first and second external gear rings having different diameters, with the first and second external gear rings engaging corresponding first and second internal gears. When rotational energy is imparted to one end of the drive shaft, the gearing arrangement imparts a rotational motion to either the first or second rotatable housing, with the housing rotating around the other end of the rotating drive shaft, which can extend outside of the dual function gearbox. Thus, the dual function gearbox generates two output motions: high torque rotation of the rotatable housing; and rotation of the drive shaft which can be used as an input rotation to additional dual function gearboxes.