Abstract: A combine harvester is configured with a chopping mechanism for chopping crop that includes a cutting cylinder equipped with knives, a knife carrier equipped with counter-knives and a friction concave plate and, downstream thereof a rasp bar. The knife carrier and the friction concave plate are each swivellable about a swivel axis, which enables the knife carrier and the friction concave plate to be moved into a position in which the counter-knives, the rasp bar or both extend at least partially into a crop stream passing through the chopping mechanism. The knife carrier and the friction concave plate are each adjusted using an actuator without the use of tools.