Abstract: An apparatus for converting a rotational movement into a back and forth movement is described, which has a spindle with an outer surface having at least one guiding groove, a bearing body with a wall section surrounding the surface concentrically and a force transfer device with at least one ball mechanism comprising at least one driving ball. The spindle and the bearing body are disposed so that they can be rotated and shifted axially relative to one another. The ball mechanism is mounted in a bearing bore in the wall section and protrudes into the guiding groove as well as towards the outside over the outer extent of the wall section. Moreover, at least one ball race, pretensioning the ball mechanism in the direction of the guiding groove, is slipped onto the bearing body.

Abstract: An apparatus for converting rotational movement into reciprocating lifting movement or vice versa, compriss a bearing body that incorporates a first, cylindrical wall section with first guide grooves, a rotary element that is supported on the bearing body so as to be able to rotate and that incorporates a second cylindrical wall section with second guide grooves that are arranged at an angle to the first guide grooves, a lifting element that is supported on the bearing body so as to move back and forth and that incorporates a third wall section, in which continuous bearing drillings with axes that are transverse to the lifting movement are arranged, and a force transfer system with driver balls that are guided within the bearing drillings. In each bearing drilling there are two driver balls that lie one behind the other in the axial direction and which rest against each other. One such driver ball is supported in part in the first guide groove and the other is supported in part in the second guide groove.