Abstract: A torsional vibration damper for arrangement in a clutch disk includes a hub element and a hub-disk arrangement arranged on the hub element. The hub-disk arrangement has a first transmission arrangement and a second transmission arrangement which is rotatable about an axis of rotation relative to the first transmission arrangement. A first damping arrangement acts between the first and the second transmission arrangement. A third transmission arrangement is connected in a rotationally fixed manner to the hub element. A second damping arrangement acts between the third transmission arrangement and one of the first and second transmission arrangements and allows a relative rotation between the third transmission arrangement and the one of the first and second transmission arrangements. Furthermore, a first friction device acts between the third transmission arrangement and at least one of the first and second transmission arrangements.

Abstract: Operating device for motor vehicles, in particular having an output cylinder and/or an input cylinder connected hydraulically to the latter. The operating device includes a housing, a cylinder arranged in the housing and a piston which can be moved back and forth in the cylinder between a rest dead point and an operating dead point. The position of the piston in the cylinder is rendered detectable by signals from at least one switch. As many switches as desired are integrated into an input cylinder, thus rendering it possible to interrogate the position of the piston via a switch unit either for a display or for data reconciliation.