In the paper, a new model of friction coupling in rolling friction is presented. Apart from slips related to elastic and plastic deformation in the area of actual contact of two bodies, the mechanism includes also inertia forces related to tangential deformations. Research concerning a model of coupling mechanism of variable ratio friction wheels is described. The main objective or the investigation was to prove that the force acting along the contact line of friction wheels is significantly affected by the shape of the contact area which had not been taken into account in the relations applied so far. A new model of the coupling mechanism was suggested and verified experimentally.