To simplify a structure, and reduce a cost by integrally installing a frame-shaped wind introducing duct for introducing a sucking wind of a cooling fan to a radiator in a radiator support in a working traveling car for installing the radiator oppositely arranged to the cooling fan in the radiator support.

In a traveling machine body of a crawler type tractor, a generator, an air conditioning compressor and a cooling fan are driven by an output shaft projecting to the front side from an engine. A radiator 14 is arranged in a front opposed position of this cooling fan, a radiator support 15 of this radiator 14 is a single plate member, and the radiator 14 is installed on this plate member to preconstitute a radiator unit to be incorporated into an engine housing part in the unit state. An air introducing duct 18 is arranged on the front side of the radiator 14, and frame rigidity is imparted to the radiator support 15 by integrally preinstalling this wind introducing duct 18 on a front face of the radiator support 15.