Pulley :
Pulley A pulley is a chain, belt or rope wrapped around a wheel. The mechanical advantage of a pulley system is approximately equal to the amount of supporting ropes or strands
Wheel and axle::
Wheel and axle: A wheel and axle is a lever that rotates in a circle around a center point or fulcrum. The larger wheel (or outside) rotates around the smaller wheel (axle). Bicycle wheels, ferris wheels and gears are all examples of a wheel and axle. Wheels can also have a solid shaft with the center core as the axle such as a screwdriver or drill bit or the log in a log rolling contest.
Inclined Plane:
Inclined Plane An inclined plane is a slanted surface used to raise an object. A ramp is an inclined plane. When an object is moved up an inclined plane, less effort is needed than if you were to lift it straight up, but, you must move the object over a greater distance. To elevate a roller coaster, it is much easier to pull it up a ramp than it is to lift it straight up
Wedge:
Wedge A wedge is an inclined plane which moves. Most wedges (but not all) are combinations of two inclined planes. A knife, axe, razor blade, and teeth are all good examples of wedges. Generally it can be anything that splits, cuts, or divides another object including air and water.
Lever:
Lever Levers are simple machines used to lift weights. First let's learn some terms you will need to know. A load is the thing you're lifting. A fulcrum is the thing that makes the load lighter. An effort is the person pushing to make the objects move.
Screw:
Screw A screw , or bolt , is a type of fastener characterized by a helical ridge, known as an external thread or just thread , wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread , often in the form of a nut or an object that has the internal thread formed into it. Other screw threads are designed to cut a helical groove in a softer material as the screw is inserted. The most common uses of screws are to hold objects together and to position objects