Control system for operating a harvesting machine (1), wherein the harvesting machine (1) is a towing vehicle (2) and at least two of the towing vehicle (2) coupled to the working units (3, 4, 5), namely at least one in the direction of movement of the harvesting machine (1) seen rear working unit (3, 4) and saw at least one in the direction of advance of the harvester (1) front working unit (5), with the or each rear working unit (3, 4) associated hydraulic control unit (6), the one of a hydraulic system (9 ) of the carrier vehicle (2) coupled hydraulic block (7) and an electronic control unit (8) and which is used to control a relief pressure for the or each rear working unit (3, 4), and wherein the or each rear working unit (3, 4 ) associated with the hydraulic control unit (6) and the control of a discharge pressure of the or each front work unit (5).
