of the casing 21 and another plurality of resistance plates 61 engaged with splines 59 formed in the outer circumferential surface of the fifth step portion 33 of the shaft 19 are alternately arranged so as to intervene between the two other resistant plates further plural locating spacer rings 63 are disposed between the two resistance plates 57 spline engaged with the casing 21 to maintain a predetermined distance therebetween in such a way as to be separated away from the outer circumference of the resistance plates 61 spline engaged with the shaft 19 the shaft 19 is formed into a hollow shaft formed with an axial through bore 65 in order to reduce the weight thereof further a sealing member 69 is disposed between the second step portion 27 of the shaft 19 and a flange portion 67 of an annular projection 45 of the casing 21 without preventing the relative rotation between the shaft 19 and the casing 21 the reference numeral 71 denotes a dust cover disposed in contact with a lip portion of the sealing member 69 the operation of the first embodiment of the apparatus will be described hereinbelow a power of the engine 1 is transmitted to the front wheels 7 via the transmission 3 and the transfer 5 and on the other hand to.