In many instances, the combination of two or more simple machines achieves results that cannot be achieved by a simple machine alone. Such combinations are known as compound machines. An example of a compound machine is the common garden hoe. The handle of the hoe is a lever, while the blade that cuts into the ground is a wedge. Machines with many simple machines combined with each other—such as typewriters, bicycles, and automobiles—are sometimes referred to as complex machines.
Bains, Rae. Simple Machines. Mahwah, NJ: Troll Associates, 1985.
Macaulay, David. The New Way Things Work. Boston: Houghton Mifflin Company, 1998.
David E. Newton
Science EncyclopediaScience & Philosophy: Linear expansivity to Macrocosm and microcosmSimple Machines - Levers, Mechanical Advantage, Pulleys, Wheel And Axle, Inclined Planes, Screws, Compound Machines - Wedges