When you push or pull with a simple machine, you are applying a force and doing work. And, if you get more force out of a machine than you put into it, then that machine has a mechanical advantage.

Throughout history, humans have developed several simple machines to make work easier. The most notable of these are known as the "six simple machines": the wheel and axle, the lever, the inclined ...

Khonsari, M.M. and E.R. Booser, Applied Tribology – Bearing Design and Lubrication, 2nd Ed. John Wiley & Sons, Ltd., West Sussex, U. K. 2008. Wilcock, D.F. and E.R ...