Abstract: An insert (10) for a rotor (14), which rotates about a rotor axis (12), of a centrifuge (16) incorporating a housing (30) having at least one container for bags, in particular blood bags, that comprises a slider (66) that cooperates with a drive, a rotatable spindle nut (62) and a spindle (64), wherein the spindle nut (62) is rotatably mounted in the housing (30) and connected to the drive, and the spindle (64) is translationally slidably mounted in the spindle nut (62) and connected to the slider (66). The slider (66) is arranged in the container and acts on the bag in a predetermined manner. The spindle (64) moves between a starting position and an operating position, wherein the spindle nut (62) is rotatably mounted in the housing (30) via at least one bearing (60). The bearing (60) is formed by a lubricant-free bearing (60) having an outer bearing ring in contact with the housing and a bearing ring in contact with the spindle nut (62).