The invention relates to a method for operating a functional element (1) which can be driven by a main drive (2) via a slip clutch (3) and/or by an auxiliary drive (4) which is coupled to the clutch (3), comprising the following method steps: determining the efficiency curve (.sub.K) of the clutch (3); determining the efficiency curve (.sub.HA) of the auxiliary drive (4); superimposing the efficiency curves (.sub.K, .sub.HA); deriving an operating zone diagram (7) from the physical limits (n.sub.E, n.sub.Kmax, n.sub.HAmax, n.sub.I, G.sub.IK) of the clutch (3) and the auxiliary drive (4); and optimizing the interplay of clutch (3) and auxiliary drive (4) determined by the superimposition of the efficiency curves (.sub.K, .sub.HA) with respect to an optimized overall efficiency curve (.sub.opt) of the auxiliary drive (4) and the clutch (3) and/or a minimized heat generation of the clutch (3).