A mechanism for switching a sample holder (14, 40) for accommodating a fluidic sample between an orbital motion mode for sample mixing, particularly for shaking, and a rotary motion mode for sample separation, particularly for centrifuging, the mechanism comprising: a gear element being drivable by a drive unit to move, particularly to rotate, selectively in a first direction or in a second direction being inverse to the first direction; an orbital motion generator (2 to 5) configured for generating an orbital motion of the sample holder (14, 40) when being operated in the orbital motion mode; a rotary motion generator (2, 4, 5) configured for generating a rotary motion of the sample holder (14, 40) when being operated in the rotary motion mode; a one-way clutch arrangement (12, 13) configured for selectively: coupling the gear element with the orbital motion generator (2 to 5) to transfer a driving force from the gear element to the orbital motion generator (2 to 5) for generating the orbital motion when the gear element is driven in the first direction and to freewheel when the gear element is driven in the second direction; or coupling the gear element with the rotary motion generator (2, 4, 5) to transfer a driving force from the gear element to the rotary motion generator (2,4, 5) for generating the rotary motion when the gear element is driven in the second direction and to freewheel when the gear element is driven in the first direction. a gear element being drivable by a drive unit to move, particularly to rotate, selectively in a first direction or in a second direction being inverse to the first direction; an orbital motion generator (2 to 5) configured for generating an orbital motion of the sample holder (14, 40) when being operated in the orbital motion mode; a rotary motion generator (2, 4, 5) configured for generating a rotary motion of the sample holder (14, 40) when being operated in the rotary motion mode; a one-way clutch arrangement (12, 13) configured for selectively: coupling the gear element with the orbital motion generator (2 to 5) to transfer a driving force from the gear element to the orbital motion generator (2 to 5) for generating the orbital motion when the gear element is driven in the first direction and to freewheel when the gear element is driven in the second direction; or coupling the gear element with the rotary motion generator (2, 4, 5) to transfer a driving force from the gear element to the rotary motion generator (2,4, 5) for generating the rotary motion when the gear element is driven in the second direction and to freewheel when the gear element is driven in the first direction. coupling the gear element with the orbital motion generator (2 to 5) to transfer a driving force from the gear element to the orbital motion generator (2 to 5) for generating the orbital motion when the gear element is driven in the first direction and to freewheel when the gear element is driven in the second direction; or coupling the gear element with the rotary motion generator (2, 4, 5) to transfer a driving force from the gear element to the rotary motion generator (2,4, 5) for generating the rotary motion when the gear element is driven in the second direction and to freewheel when the gear element is driven in the first direction.