Simple machine elements

A machine is a tool that helps you user your energy more effectively. Machines, no matter how complex it is, it has the same character to converts and or transfer movement from actuator to manipulator, from rotary motion to axial motion. In order to do this, it is constructed with a lever, inclined plane, wheel and axle, pulley, and screw. Those are called a simple machine elements.
In order to works, machines can not work 100% efficiently because they are limited by the friction. Anyway, without friction machine can't run, instead you can not run on asphalt. Thx to friction. 
Actually there are only two machine; lever and inclined plane
Now, take an attention to the lever