the input shaft 100 is supplied through the sleeve 108 to the output shaft 102 in the auto mode so that the driving power can be transmitted to the rear drive shaft at the same time the front drive shaft 122 receives the power from the output shaft 102 through the multi plate clutch 112 and the chain 120 under this condition the differences in revolution between the front wheels and the rear wheels are adjusted by the multi plate clutch 112 in the low mode the sleeve 108 supplies the power of the input shaft 100 through the planetary carrier 106 to the output shaft 102 so that a low velocity driving force or torque can be transmitted to the output shaft 102 compared with the auto mode the strong driving force or torque thus created is transmitted through the multi plate clutch 112 to the front drive shaft 122 as shown in fig3 and 4 similar to the typical automatic transfer case a sleeve 1 rotates together with an output shaft 102 and is preferably coupled to the output shaft 102 with splines so that the sleeve 1 is capable of linear movement along the axial or longitudinal direction of the output shaft 102 a rack 3 is formed parallel to the output shaft 102 by varying the shape of the portion where the conventional shift fork is connected the rack 3 is preferably provided with a plurality of round teeth in one row because the sleeve 1 is of a rotating cylindrical shape a rotation torque supplying mechanism is connected to the rack 3 and meshed to it and therefore the sleeve 1 can be linearly moved on the output shaft.