A conditioner unit (6) for conditioning an agricultural crop material comprises a pair of rolls (20a, 20b) configured for rotation in opposite directions and providing a nip (22) through which crop material passes. An adjusting mechanism (31) is provided for adjusting a pressing force applied by the rolls (20a, 20b) to the crop material as it passes through the nip. The adjusting mechanism (31) includes at least one hydraulic actuator (30) connected to at least one of the rolls (20a, 20b) and a hydraulic circuit (33) that supplies hydraulic fluid to the actuator (30), the hydraulic circuit being configured so that in a first operational mode the rolls (20a, 20b) are pressed towards one another and in a second operational mode the rolls (20a, 20b) are pushed apart to provide a gap between the rolls.
