| 摘要 |
PROBLEM TO BE SOLVED: To provide a fan drive for a construction machine capable of cooling a cooling device even if an electric system is broken down. SOLUTION: This fan derive is provided with a pilot type regulator 2a reducing a discharge quantity of a hydraulic pump 2 as increasing the value of a pilot pressure and increasing the discharge quantity of the hydraulic pump 2 as decreasing the value of the pilot pressure, an electromagnetic proportional valve 8 outputting the pilot pressure with the value proportional to the current value to the regulator 2a, and a controller 7 outputting the electric signal whose current value is reduced as the temperature of the cooling fluid of a cooling device 5 increases and whose current value is increased as the temperature decreases, to the electromagnetic proportional valve 8. When the electric signal is broken off, the regulator 2a sets the discharge quantity of the hydraulic pump 2 to the maximum, or when stopping of the engine 1, the controller 7 outputs the electric signal to the electromagnetic proportional valve 8 and controls the regulator 2a so that the discharge quantity of the hydraulic pump 2 becomes the minimum.
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