Method for sharpening knives of an agricultural vehicle

An agricultural vehicle comprising:

• a housing comprising a transition door;
• a cutter drum carrying cutting knives in the housing, wherein the transition door is below the cutter drum;
• a sharpening stone;
• a sharpening door shielding the sharpening stone;
• and
• a controller configured for performing steps of:
• rotating the cutter drum while keeping the sharpening door closed so an overpressure is created inside the housing, the sharpening door shielding the sharpening stone from the cutting knives while creating the overpressure;
• opening the transition door to eject crop material through the open transition door;
• opening the sharpening door to expose the cutting knives to the sharpening stone and closing the transition door;
• grinding one or more of the cutting knives with the exposed sharpening stone;
• and
• closing the sharpening door to shield the sharpening stone from the cutting knives after the grinding.