In flexible shaft couplings, the transmission of power works via interlocking claws. They do so alternately. The spaces that are created are filled by the flexible gear rim. The teeth of the rim are usually crowned so that they can more easily compensate for misalignments of the shafts.
Torsionally flexible shaft couplings are used wherever vibrations or non-critical load peaks occur that should not be transmitted to the drive train. The damping element cushions these loads, thus ensuring smooth running in the drive train and protecting against damaging loads.