A harvesting machine includes a self-propelled vehicle adapted for separating grain from non-grain material, a cleaning shoe and a fan for controlling air flow. The fan is positioned downstream of the cleaning shoe and the fan having an air inlet for providing air to the fan and an aspiration outlet for providing air from the fan. The fan assists in reducing static air pressure within the harvesting machine. The fan may be a centrifugal fan. The harvesting machine may further include a chopper operatively connected to the vehicle and adapted for receiving the non-grain material and chopping the non-grain material and a blower adapted for assisting in conveying the non-grain material from the chopper such as for collection in a collection container.