The combination of a wheel and axle is a simple machine that consists of a large wheel attached to a smaller wheel called an axle that turns on the same axis. When the large wheel is turned, the axle also turns.The wheel can be used to create a mechanical advantage. Turning something heavy is easier by spinning a wheel that is fixed to an axle that is attached to the heavy object. Alternatively, plenty of force can also be used to turn the axle, causing the wheel to spin faster.The wheel and axle decrease the amount of effort required to do work. This simple machine has been used for centuries to magnify force. It changes the direction and amount of force applied to turn or move an object located at the axle. The wheel allows a person to apply force on a greater distance, which reduces the effort needed to move a load.For example, a car's steering wheel enables the driver to exert force on the wheel's outer edge to turn the axle (i.e., the front wheels). Another example is a round doorknob. When turning the larger handle, a smaller axle turns to move the door latch. Other examples of wheel and axle devices are tires, pencil sharpeners and Ferris wheels.
