Abstract: In general, the invention relates to wind turbines, the rotor blades of which can be adjusted in terms of their pitch angle. The invention relates in particular to an actuating drive for adjusting the pitch angle of a rotor blade of a wind turbine, comprising a large rolling bearing which comprises two bearing rings that can be rotated relative to each other, and an actuator for rotating the two bearing rings relative to each other. According to the invention, the actuating drive comprises a ring channel cylinder, which is formed in one of the bearing rings, and at least one piston, which is received in the ring channel cylinder in a movable manner and is drivingly connected to the other bearing ring of the two bearing rings.

Abstract: An apparatus for damping torsional vibrations in a drivetrain, including a drive device and an output device, which drive device and output device are arranged so as to be rotatable around a common axis, a damping device that connects the drive device and the output device to one another, and a thrust bearing device for axial support of drive device and the output device. The drive device, cover device, and thrust bearing device are arranged such that a partially enclosed spatial region is formed, and at least one damping element of the damping device is arranged in the spatial region. Elements of the drive device, the cover device, the output device and the thrust bearing device are arranged to inhibit liquid entry into the spatial region.