The mechanical fan is a machine that consists of a blade assembly powered by an electrical motor, however, this can also be a handheld device that is simply moved back and forth to move the air. Manufactured in a variety of sizes and styles, the mechanical fan can be run on household current or battery power to move hot and cold air. From the propeller-like, axial-style fan found in box fans and ceiling fans to the centrifugal fan, the mechanical fan is manufactured in many styles. Each type provides a particular advantage when installed in a specific application.
One of the earliest mechanical fan designs is the handheld fan. This can be an accordion-like, foldable device or a simple tree leaf that is waved in a back-and-forth motion to create a breeze. This type of fan is often used to cool a person or to fan a fire to allow the flame to grow higher and hotter. Another version of this most basic mechanical fan is called bellows. Used by the blacksmith trade for decades to create a hotter fire, bellows simply compress air and propel it out of the body of the device with force.
The type of mechanical fan most common and most familiar to many people is the axial fan. This style of fan uses a blade or a system of blades to move air at right angles or parallel to the shaft that the blade assembly is mounted to. In a typical home-use box fan, a five-bladed fan is turned by a small, electrical motor to move air throughout a room. Commonly equipped with three speeds, this type of mechanical fan is often used in warm climates to maintain a comfortable climate in the home. This is also the type of fan that is used in many different types of electrical devices to provide cooling to the components or to discharge built-up heat from the device.
The centrifugal fan is commonly called a squirrel cage. It moves air by spinning an impeller, a circular, drum-like device consisting of raised slats, through the use of an electric motor and a rubber belt. Used in furnaces, car heaters and many air-conditioning systems, this type of mechanical fan is capable of moving large volumes of air, often at slow speeds. Similar to the centrifugal fan is the cross-flow fan, this mechanical fan is used primarily in heating and cooling applications and also uses an impeller to move the air.