Torque controlled safety couplings are used as safety elements in drive trains. Their function consists in separating input side and output side when the limit for the transferrable torque is exceeded. Main property of these couplings is the switching torque, the maximum transferrable torque before initiating the separation of the drive train. Target of the project is to examine the characteristics of the switching torque of form fitting safety couplings. Doing so three couplings of well known manufacturers are examined. Main result of the test is that the switching torque of form fitting safety couplings is underlying parameter dependencies and scatter. Safety and exploitation of the drive train are in cases considerably depended on the given point of operation and the coupling adjustment. In this respect it is of importance, to choose, to adjust and to operate the covered couplings systematically.