Straw chopper for a combine harvester having counter-blades and a straw dam

A straw chopper for a combine harvester, comprising:

• a housing that has an inlet and an outlet;
• a rotor with suspended chopping blades that is arranged in the housing;
• adjustably arranged counter-blades adapted to be moved both into and out of an envelope circle of the chopping blades;
• and
• a straw dam adapted to be moved between an active, operating position, in which it cooperates with the chopping blades at a position downstream of the counter-blades in order to comminute the straw, and an inactive, non-operating position,
• wherein adjustment of the straw dam is coupled to adjustment of the counter-blades;
• and
• a mechanism adapted to adjust both the counter-blades and the straw dam, wherein an initial actuation of the mechanism moves the counter-blades from a non-operational position outside the envelope circle to a first operating position inside the envelope circle, and wherein a further actuation of the mechanism moves the straw dam from the inactive, non-operating position to the active, operating position.