The invention relates to a positioning device for a sample distribution apparatus, in particular a pipetting apparatus, providing a first part, at which a sample transport device can be arranged, a second part, at which a sample holder can be arranged, wherein the first part and the second part are arranged moveable in relation to each other between a first position and an adjusted target position of the first and second part for performing a positioning motion, such that a sample can be conveyed towards the sample holder by the positioning motion between the first position and the adjusted target position and is conveyable at the target position by release from the sample transport device to the sample holder, or can be conveyed in the sample transport apparatus towards the sample holder by the positioning motion between the first position and the adjusted target position and is conveyable by a motion of the sample transport device relative to the first part into a release position and is conveyable at the release position by release from the sample transport device to the sample holder, wherein an actuation motion is provided, which serves the conveyance of the sample, a positioning auxiliary device, which provides at least one means for limiting and the relative mobility of the first and the second part in the adjusted target position, which provides, preferably, at least one means for adjusting the n-th target position from a plurality of N predetermined target position as the adjusted target position, which, preferably, provides at least one means for changing of the adjusted target position from the n-th target position to an (n+1)-th target position, and which further provides at least one first means for
coupling of said actuation motion and said positioning auxiliary device, or to the at least one means for changing of the same such that the actuation motion can effect the change from said n-th target position to said (n+1)-th target position via said at least one first means for
coupling. The invention relates to a corresponding working method for the automatical change of a position of a first part relative to a second part and relates further to a sample distribution apparatus with such a positioning device.