Abstract: A control device for a hydraulically driven fan is provided with a cooling fan which is rotated by a hydraulic motor and carries out ventilation for cooling a working fluid. Further, the control device for the hydraulically driven fan is provided with a sensor for detecting a temperature of the working fluid, and a lever switch for detecting whether a working mechanism actuated by the engine is in a stopped state, by determining whether a working machine lever has been operated. In order that a resonance between the cooling fan and the engine is suppressed, the control device for the hydraulically driven fan further adjusts a rotating speed of the hydraulic motor in correspondence to a detection result by the lever switch. In the case that a stopped state of the working mechanism is detected on the basis of an operation state of the working machine lever by the lever switch, the rotating speed of the hydraulic motor is adjusted.

Abstract: A control device for a hydraulically driven fan is provided with a cooling fan which is rotated by a hydraulic motor and carries out ventilation for cooling a working fluid. Further, the control device for the hydraulically driven fan is provided with a sensor for detecting a temperature of the working fluid, and a lever switch for detecting whether a working mechanism actuated by the engine is in a stopped state, by determining whether a working machine lever has been operated. In order that a resonance between the cooling fan and the engine is suppressed, the control device for the hydraulically driven fan further adjusts a rotating speed of the hydraulic motor in correspondence to a detection result by the lever switch. In the case that a stopped state of the working mechanism is detected on the basis of an operation state of the working machine lever by the lever switch, the rotating speed of the hydraulic motor is adjusted.