Abstract: A chopper drum assembly for a forage harvester including a chopper drum housing, a shear bar, a shear bar holder and a wear plate assembly. The chopper drum housing includes a first part and a wear plate assembly support surface. The shear bar holder is pivotally connected at a first end to the first part of the chopper drum housing and fixedly connected to the shear bar at a second end. A first end of the wear plate assembly is pivotally connected to the second end of the shear bar holder adjacent the shear bar, and a second end of the wear plate assembly is supported by the wear plate assembly support surface wherein, the wear plate support surface is arranged to be inclined to the horizontal.