3 classes of the simple machine?

Simple machines are typically classified into six categories: lever, pulley, inclined plane, wheel and axle, screw, and wedge. However, if we focus on three classes, we can consider levers, which amplify force; pulleys, which change the direction of force; and inclined planes, which reduce the effort needed to lift objects by spreading the distance over which the force is applied. Each class simplifies work by altering the mechanics of movement and force application.