Tensioner for a flexible drive element

In a tensioning device (S) for a flexible drive element (E) such as a belt or chain of a drive (T) of an internal combustion engine connecting at least a crankshaft and a starter/generator (SG), a first and a second tensioning roller (R1, R2) are provided on a pivotally mounted tensioning arm (H). The drive element (E) is deflected at the tensioning rollers (R1, R2) in such a manner that the resultants (F1, F2) of the deflection forces produce a moment couple of opposite directions with respect to the pivot bearing (L). The tensioning rollers (R1, R2) are arranged at the tight run sides (ZK, ZS) of the driving crankshaft (K) or of the driving and structurally integrated in the generator (SG) starter drive motor.