A rotational damper includes a damper housing surrounding an electromagnetic damper motor and connected to a first mass via a fastening part; a coupling lever supported for pivoting relative to the damper housing and connected with a second mass; a strain wave gear mechanism for damping vibrations and including a rigid unit having an internal spline and being connected with the damper housing, and a flexible unit having an external spline and being fastened with the fastening part, wherein the first and second units are coupled with each other via the internal and external splines; a wave generator rotatably supported in the flexible unit, wherein a rotation of the wave generator causes a deformation of the flexible unit; and a wrap spring connected on one side in rotative fixed relationship with the coupling lever, and on another side connected in rotative fixed relationship with the fastening part, wherein at a predetermined pivoting of the coupling lever relative to the fastening part the wrap spring deforms the flexible unit thereby blocking the strain wave gear mechanism.