To prevent an operator cab from bering exposed to heat emitted from an engine, in a wheel type work vehicle, whose lower traveling body has a chassis frame provided with an engine, a heat exchanger including a cooling fan, and a transmission, and whose upper turning body mounting a work machine device thereon is rotatably installed to an upper part of the chassis frame of the lower traveling body.

A hydraulic motor rotation direction selector valve is provided between a hydraulic pump performing rotary drive of the cooling fan for the heat exchanger and a pressure oil circuit of a hydraulic motor. Rotation direction of the cooling fan is switched between forward rotation and reverse rotation after switching control of the hydraulic motor rotation direction selector valve so as to prevent movement of the heat emitted from the engine to an operator cab side caused by an outside air flow by a cooling fan, depending on cases, that is, a case where a working machine and the upper turning body are driven and the working vehicle is set in a low speed traveling operation mode, and a case where the working vehicle is set in low speed-high speed traveling modes preventing the drive of the working machine and the upper turning body.