Abstract: A mower deck with fan structure rotatable with the blade spindle for creating an air turbulence to prevent debris buildup around the spindle and to exhaust debris away from and cool the mower drive train area. In one embodiment, an attachment including a plurality of vanes is connected to the lower side of the driven spindle sheave to create an air disturbance around the spindle. In another embodiment, the sheave is apertured and includes integral vanes projecting downwardly from the apertures. The fan structure draws air in from a first drive cover port located above the blade spindle and exhausts air and airborne debris through a second port in a high pressure side of the cover.