WHILE REMOVING LARGE EXHAUST FAN IN CLINKER TUNNEL, IT WAS BEING PULLED OUT ONTO A 2X12 BOARD BEING USE FOR A RAMP TO GET IT TO THE FLOOR. THE FAN TIPPED OFF OF THE BOARD BUT WAS STILL ATTACHE D TO CHAIN FALL THAT CAUSED IT TO SWING TOWARD THE INJURED STRIKING HIM ON THIS LEFT LEG AND GROIN AREA.