A combine harvester (10) comprises a threshing and separating mechanism (16) mounted to a main frame (11), which includes a generally cylindrical chamber (26) having a generally longitudinal axis, and a separating concave assembly (101). The arrangement further includes a rotor assembly (27) mounted for rotation in said chamber and comprising a generally cylindrical rotor body (50) with a separating concave assembly. The separating mechanism (16) further comprises a beater assembly (128) arranged behind said concave assembly (101) for receiving threshed and separated crop material therefrom and projecting it rearwardly. The beater assembly comprises a transverse guide means (125) mounted behind said separating concave assembly (101) and below said rotor body (50), and a transverse beater rotor (127). The chamber (26) comprises a curved guide plate (101) and above said guide means (125). This guide plate (130) distributes the separated crop material over the full width of said guide means (125) in order to minimise the chance that material starts accumulating in the one or other corner and the separating system gets plugged.
