A machine is classified as a compound machine when?

A machine is classified as a compound machine when it consists of two or more simple machines working together to perform a task. Simple machines include levers, pulleys, inclined planes, wheels and axles, screws, and wedges. Compound machines utilize the mechanical advantages of these simple machines to increase efficiency and reduce the amount of force needed to accomplish work. Examples include a bicycle, which combines wheels, levers, and pulleys.