The given calculation methods for the design of flexible shaft couplings contain mostly empirical load factors and, moreover, apply only to the linear two-mass oscillator under specific operating conditions.*In cases, where for reasons of technical safety or due to the technical complexity of the plant which is to be calculated, rough calculations are no longer admitted and specific facts of multi-mass systems are to be taken into account in view of time slopes of loading; non linear springs, clearance etc, it is to be proceeded to calculation methods which are mathematically more elaborated (e.g. simulation method).*In order not to impair or influence the progress* in this field by the inexpedient standardization of modern calculation methods for plants, clause 3.4 gives only general information on this subject.