When cars turning left and right sides of the wheel due to the different trajectory radius, so the journey through different cornering, the outside wheel through a long journey, if powered by a shaft to complete the same-sized wheels, two Like speed, but also the same as the diameter of the two wheels when cornering traveled is not the same, it would need to curve inward wheel slippage (do not walk), made turning difficult; to overcome, to improve this problem, the vehicle drive shaft divided into two halves, parted in the middle with "differential" connection, when the vehicle upright with two rounds can be the same driving force, while cornering, due to the differential, the inside of the wheel rotational speed lower than the outside wheel this, to a two-wheel drive vehicle forward while wheel movement from the outside but the inside than the larger purpose. Two axle shaft is to improve cornering performance and vehicle design.