Disclosed is a grain separating apparatus (1) for a combine harvester (2). The grain separating apparatus (1) comprises at least a first walker-sieve (3) and a second walker-sieve (4) arranged side by side, wherein the first walker-sieve (3) and the second walker-sieve (4) are suspended in at least two suspension points (5,6) in the combine harvester (2) and wherein at least one of the two suspension points (5,6) is arranged to describe a rotational motion. A rotational motion drive (7) is arranged to drive the rotational motion of the first walker-sieve (3) out of phase with the rotational motion of the second walker-sieve (4), wherein each of the at least two walker-sieves (3,4) include a straw walker (8) comprising drivers (9) for conveying a straw material (10) and wherein grain (11) and debris (12) are separated from the straw material (10) through walker apertures (13) arranged in the straw walker (8). Furthermore, the straw walker (8) is arranged on top of at least one sieve (14,15) which is arranged to separate grain (11) from the debris (12) and wherein the straw walker (8) and the at least one sieve (14,15) are rigidly connected. Furthermore, a method for separating grain (11) from straw material (10) in a combine harvester (2) by means of a grain separating apparatus (1) as described above.L'invention concerne un appareil de séparation de grain (1) pour une moissonneuse-batteuse (2). L'appareil de séparation de grain (1) comprend au moins un premier tamis-secoueur (3) et un deuxième tamis-secoueur (4) disposés côte à côte, le premier tamis-secoueur (3) et le deuxième tamis-secoueur (4) étant suspendus par au moins deux points de suspension (5,6) dans la moissonneuse-batteuse (2) et au moins un des deux points de suspension (5,6) étant agencé pour décrire un mouvement de rotation. Un entraînement de mouvement de rotation (7) est agencé pour entraîner le mouvement de rotation du premier tamis-secoueur (3) en déphasage par rapport au mouvement de rotation du
