Force multipliers, also known as simple machines, are devices that are able to provide greater output force than input force. Levers, pulleys, ramps, screws, axles and wedges are all force multipliers that operate using basic physical principles in order to increase output force and make work easier.
Work is defined as applying force to an object in the direction of motion. Simple machines make it possible to increase the amount of usable output force either by reducing friction or producing greater output force by increasing the distance that force must be applied. Simple machines are also able to change the direction of force that is being applied, making it possible to transfer force from one place to another.
Force multipliers have been in use since ancient times. Simple machines played a vital role in many of the earliest construction and engineering efforts, making possible feats that could not have been accomplished without mechanical assistance. Some of these machines, such as the wheel and the axle, rank among the most important human inventions in all of history. Several more sophisticated machines utilize one or more of these force multipliers working in concert in order to provide greater effect or to increase the magnitude of force being multiplied.