Abstract: A ball screw includes a spindle element which has a first groove arrangement on an outer circumferential surface, a nut element which surrounds the spindle element and has a second groove arrangement on an inner circumferential surface, and a plurality of balls, at least some of which engage into the first groove arrangement and the second groove arrangement. The nut element is rotatable about an axis of rotation with respect to the spindle element, and, during the rotation of the nut element about the axis of rotation with respect to the spindle element, the balls which engage into the first groove arrangement and the second groove arrangement roll in the first and the second groove arrangement, while at the same time rotate about respective ball axes of rotation.

Abstract: A friction clutch for motor vehicles has a casing which can be connected in a rotationally fixed manner to a driven flywheel mass. A pressure plate is arranged inside the casing with a pressure spring supported between the clutch casing and the pressure plate so that the pressure plate presses a clutch disk, which is provided with friction linings, onto the flywheel mass. The pressure spring, during engagement of the clutch, exerts a varying pressure force on the pressure plate. The friction clutch also having a device which acts on the pressure plate and varies essentially proportionally to the force of the pressure spring to force of the pressure plate.