A power transmission device is comprised of a first shaft having a first gear and a second gear and capable of being drivingly coupled with the engine; a second shaft drivingly coupled with the electric motor and the first shaft; a third gear meshing with the first gear to form a first gearing having a first gear ratio; a fourth gear coaxial with the third gear, the fourth gear meshing with the second gear to form a second gearing having a second gear ratio; a third shaft coaxial with both the third gear and the fourth gear, the third shaft being drivingly coupled with the axles; a first clutch configured to selectively connect and disconnect the third gear with the third shaft; and a second clutch configured to selectively connect and disconnect the fourth gear with the third shaft.