An agricultural harvester (10) including a chassis (12), and a threshing section (24) carried by the chassis (12). The threshing section (24) includes a rotor (40), a plurality of frame assemblies (72, 74, 76, 78) adjustably positioned proximate to the rotor (40), a plurality of concaves (42) and an adjustment mechanism (70 or 170). Each concave (42) is carried by a corresponding frame assembly (72, 74, 76, 78). The adjustment mechanism (70 or 170) is coupled to the frame assemblies (72, 74, 76, 78). The adjustment mechanism (70, 170) comprises a first adjustment member (80, 180), adjustingly coupled to each of the plurality of frame assemblies (72, 74, 76, 78) by a respective plurality of linkages (82, 84, 86, 88, 182, 184, 186, 188). The respective linkages (82, 84, 86, 88, 182, 184, 186, 188) have different lengths and/or angular orientations relative to the first adjustment member (80, 180).
