Abstract: An agricultural harvesting machine, such as a forage harvester, comprises a plurality of crop processing means (20, 21, 26, 27, 36,38, 49), which are driven in a first sense by an engine (70) through a main clutch (124) and a first drive line portion (111, 112, 39, 87, 89) or a second drive line portion (73, 75, 77, 80, 81, 83). A motor means (110), coupled to the first drive line portion and operable to drive one of the crop processing means, such as a cutterhead (36), in a second sense, opposite to the first sense, is permanently coupled to said first drive line portion, so that during normal harvesting it can provide driving power to auxiliary devices. The second drive line portion is linked to the first drive line portion by means of a belt transmission (95, 99, 100), which is engaged by a hydraulic cylinder (106) when the main clutch (124) is engaged. The first drive line comprises an overrun clutch (87) which is disengaged when the rotation of the cutterhead (36) is reversed by the motor means (110).