Patent ID: 8327811

Claim:
A rotary working machine comprising: a bonnet incorporating an engine and an air discharging cooling fan for radiating heat from the engine, wherein the bonnet is formed in a side surface thereof with an opening for discharging a cooling airflow from the cooling fan; a duct disposed in the bonnet and interposed between the cooling fan and the opening, wherein a duct is formed with an arc-shaped slot; a louver arranged in the duct, the louver including: a frame fixed to the duct; parallel blades aligned in a vertical row, each of the blades having first and second sides, wherein the first sides of the blades are pivotally connected to the frame so as to be aligned in a vertical row so that the second side of each of the blades is rotatably centered on the first side thereof; and a vertical lever which is vertically movable relative to the frame, wherein the second sides of the blades are pivotally connected to the lever so as to be aligned in a vertical row and so as to be vertically movable together with the lever relative to the first sides of the blades while keeping the blades in parallel, and wherein the lever has an upper end portion contacting the duct; and a fastener fastening the upper end portion of the lever to the duct via the arc-shaped slot so as to fix the blades at an optional angle, wherein the fastener can be loosened to allow the vertical movement of the lever for changing the angle of the blades.