An axle is a rod that goes through a wheel and allows the wheel to move. It is a simple machine which rolls easily, and is used to lift or move heavy loads, or to multiply the distance travelled. Cars, cycles, and wagons all move with the help of wheels and axles.
Some examples of wheels and axles include door knobs, rolling pins, record players and a ceiling fan. A wheel and axle is a simple machine, and other examples include a pencil sharpener and the wheels on roller skates.
Simple machines are machines that do not have internal energy, but they multiply the force that is applied to the machine. For instance, the wheel and axle moves the force from the smaller input to a larger output. The smaller input is the axle, which acts as a fulcrum. It moves the force the wheel, which creates a larger output since it covers more distance.