<p>The control circuit has a single hydraulic variable displacement pump (10) and a hydraulic motor (20) utilized for driving fans, where driving torque of the hydraulic motor is controlled by adjusting an absorption volume of the hydraulic motor. A speed of the fans is adjustable by the hydraulic motor, and the displacement pump is provided in the control circuit. A control of the driving torque and/or of the fan speed is steplessly varied between standstill of the fans and maximum fan speed, where the fans and/or the hydraulic motor are connected in parallel to each other.</p>
