The fan or impeller is the disk shaped structure with fins that creates the actual suction in a vacuum cleaner. It is always placed directly onto the shaft of the Suction Motor so that it spins at a very high speed.
Suction is created by the effects of centrifugal force acting upon the spinning air within the fan.
As the fan rotates, the spinning air moves outward away from the hub, creating a partial vacuum which causes more air to flow into the fan. The fan is often considered an integral part of the suction motor since it, the fan housings and the motor are assembled as a unit by the manufacturer. The more powerful suction motors contain two or three fan stages pulling in series. There are two basic vacuum cleaner fan designs. The traditional upright design is often referred to as the dirty-air design since the air going through the fan is still carrying the dirt which was picked up.