An agricultural vehicle (100, 110) includes a chassis (150) and a header (120) carried by the chassis. The header (120) includes a cutterbar (130) with at least one cutting unit (210). The at least one cutting unit (210) includes a rotary driver (230)； a rotatable disc (220) coupled to the rotary driver； at least one knife mount (350) coupled to a disc surface (321) of the rotatable disc and including a locking portion (351) being able to bias towards the disc surface； and at least one knife (240) lockable in at least one direction by the locking portion (351), the knife (240) defining at least one cutting edge (241).
