In a mechanism where movement is transferred from one component to another by frictional contact and where the intensity of the frictional contact can be changed by altering the contact pressure, a method for determining the amount of slippage between the component parts uses a measurement of a value that corresponds to the power loss due to friction, also known as power dissipation, which occurs during the transfer of movement between the component parts. In this measurement, the level of power dissipation is determined in dependence on the contact pressure force, and an increase in the amount of the dissipated power that occurs when the contact pressure force decreases is interpreted as slip.