A combine harvester (10) comprises a threshing unit (16) arranged to receive and thresh a crop stream. Separating apparatus (24) are located downstream and rearward of the threshing unit (16) and are arranged to receive the threshed crop stream and convey such a rearward direction. The front of a return pan (26), disposed below the separating apparatus (24), overlaps the rear of a stratification pan (22), disposed below the threshing unit (16). The stratification pan (22) is driven in an oscillating manner to convey a primary grain/chaff stream rearwardly to a rear edge (22R) from where the primary grain/chaff stream falls under gravity into a cleaning unit. The return pan (26) is driven in an oscillating manner to convey a secondary grain/chaff stream forwardly to a front edge (26F) from where the secondary grain/chaff stream falls under gravity to combine with the primary grain/chaff stream on the stratification pan (22). The cleaning unit comprises a fan (46) for generating a cleaning airstream which is directed through the falling grain/chaff stream to encourage the lighter material away from the grain. A plurality of crop flow disrupting elements (80) in the form of fins or tines are secured to the underside of the return pan (26) above the stratification pan (22) to disrupt the grain/chaff stream and enhance stratification thereof.L'invention porte sur une moissonneuse-batteuse (10), qui comprend une unité de battage (16) agencée de façon à recevoir et à battre un courant de culture. Des appareils de séparation (24) sont situés en aval et en arrière de l'unité de battage (16), et sont agencés de façon à recevoir le courant de culture battu et à transporter celui-ci dans une direction vers l'arrière. L'avant d'un bac de retour (26), disposé en dessous de l'appareil de séparation (24), chevauche l'arrière d'un bac de stratification (22), disposé en dessous de l'unité de battage (16). Le bac de stratification (22) est entraîné d'une manière oscillante pour transp
