A chopper assembly for harvesting equipment including a rotary chopper device with a plurality of knives and a cylindrical chopper grate assembly spaced from the rotary chopper to form a passageway for crop residue. The chopper grate assembly includes a plurality of slots extending in the direction of crop residue flow. A knife bank assembly includes a plurality of knife elements aligned with and insertable in the slots with the knife bank assembly being displaceable toward and between a position where the bank knife elements are fully inserted through the slots into the passageway and a position where they are substantially clear of the passageway. A deflector is provided for covering the slots and the deflector is displaceable with the knife elements to uncover the slots as the knife elements are displaced through the slots and into the passageway.