PURPOSE: To enable cooling to be exceedingly effective at any place by providing a radiator facing an electric rotary fan at the outside of a cooling water tank, and connecting a forced feeding pipe from said cooling water tank to the inlet port of said radiator.

CONSTITUTION: Cooling water in a cooling water tank 1 is fed to the inlet port of the radiator 26 of a radiator device 22 provided out of the aforesaid tank through both a pump 20 arranged in the outside or inside of the cooling water tank 1 and a forced feeding pipe 21. Cooling is effected by a rotary fan 25 acting for the radiator 26 for letting cooling water be returned to the inside of the cooling water tank 1 by a return pipe 27 so as to be circulated wherein the heat in respective sections of a blower mounted in the inside of the cooling water tank 1 is absorbed for effecting cooling. This constitution thereby enables the cooling of the blower to be exceedingly effected at any place.