A positioning assembly including a base part and a holder part for holding a device , the assembly further including a motor for driving a displacement mechanism mounted to the base part, the assembly being configured to adjust a position of the holder part relative to the base part between a retracted position and an extended position, along a linear displacement axis extending in longitudinal direction (z), wherein - the base part comprises a first guide rail extending in the longitudinal direction; - the holder part comprises a second guide rail extending in the longitudinal direction; - the base part and the holder part are arranged parallel to each other and are connected via a slide link which is configured to slide on each of the first and second guide rails , and - the slide link is coupled to the displacement mechanism , which is configured to displace the slide link relative to the base part in longitudinal direction (z), characterized in that: the holder part is moveably coupled to the base part via a coupling arrangement configured such that linear displacement of the slide link relative to the base part in one direction causes linear displacement of the holder part relative to the slide link in the same linear direction, the coupling arrangement comprising: ▪ a first linear drive surface provided on the base part in longitudinal direction (z), facing in a transverse direction (y); ▪ a second linear drive surface provided on the holder part in longitudinal direction (z), facing the first linear drive surface; and ▪ at least one drive wheel provided on the slide link having a rotation axis in a direction (x) perpendicular to the transverse direction (y) and the longitudinal direction (z), arranged such that a circumferential drive surface simultaneously engages the first linear drive surface on the base part and the second linear drive surface on the holder part . - the base part comprises a first guide rail extending in the longitudinal direction; - the holder part comprises a second guide rail extending in the longitudinal direction; - the base part and the holder part are arranged parallel to each other and are connected via a slide link which is configured to slide on each of the first and second guide rails , and - the slide link is coupled to the displacement mechanism , which is configured to displace the slide link relative to the base part in longitudinal direction (z), the holder part is moveably coupled to the base part via a coupling arrangement configured such that linear displacement of the slide link relative to the base part in one direction causes linear displacement of the holder part relative to the slide link in the same linear direction, the coupling arrangement comprising: ▪ a first linear drive surface provided on the base part in longitudinal direction (z), facing in a transverse direction (y); ▪ a second linear drive surface provided on the holder part in longitudinal direction (z), facing the first linear drive surface; and ▪ at least one drive wheel provided on the slide link having a rotation axis in a direction (x) perpendicular to the transverse direction (y) and the longitudinal direction (z), arranged such that a circumferential drive surface simultaneously engages the first linear drive surface on the base part and the second linear drive surface on the holder part . ▪ a first linear drive surface provided on the base part in longitudinal direction (z), facing in a transverse direction (y); ▪ a second linear drive surface provided on the holder part in longitudinal direction (z), facing the first linear drive surface; and ▪ at least one drive wheel provided on the slide link having a rotation axis in a direction (x) perpendicular to the transverse direction (y) and the longitudinal direction (z), arranged such that a circumferential drive surface simultaneously engages the first linear drive surface on the base part and the second linear drive surface on the holder part . <EOS>