Abstract: The invention relates to a torsional vibration damper with a flexible coupling (2), comprising at least one first coupling element (3) which can be connected to a driving element, at least one second coupling element (4) which can be connected to a power take-off in a rotationally fixed manner, said elements being at least indirectly coupled to each other via spring and/or damping coupling means (5). The damper also comprises a device (6) for detecting at least one variable that is at least indirectly characteristic of the mode of functioning and/or operation of the flexible coupling.