Complex machines are machines that are formed by the combination of two or more simple machines. The simple machines used for the construction of complex machines include inclined plane, wedge, screw, pulley, wheel and axle, and lever. They are also known as compound machines.
A pair of scissors is a prominent example of complex machines. It is made up of two simple machines, namely a wedge and a lever. The blades of the scissors are wedge-shaped, whereas the handles of the scissors act as the first-class lever.
A wheelbarrow is a combination of three simple machines, namely, an inclined plane, a wheel and axle combination, and a lever. The container of the wheelbarrow is an inclined plane that helps store the load easily. The handles of the wheelbarrow act as levers, allowing the user to lift the load easily. The wheel attached to the base of the wheelbarrow is the wheel and axle arrangement that helps the machine move from one place to another with ease.
A can opener comprises four simple machines, namely, lever, gear, wheel and axle, and wedge. The arms of the can opener act as two levers that help to grip and open the can. The cutter attached to the mouth of the opener is a wedge that helps the machine pierce right through the metallic body of the can. The round part attached to the opener is the gear that rotates and helps the user hold the can still. The rotating handle is the wheel and axle simple machine that supplies energy to the gear and the wedge.
A stapler is a complex machine that is made up of two simple machines, namely, a lever and a wedge. The punching mechanism of the stapler acts as the second-class lever, whereas the stapler pins act as the wedges. When the user applies push force to the lever of the stapler, the wedge-shaped stapler pin pierces through the papers, thereby simplifying the task of attaching two papers together.
The stick of the fishing rod is an example of a first-class lever simple machine where the load is attached at one end, the force or the effort is applied from the opposite end, and the fulcrum is present in the middle. The winding and unwinding of the reel are done with the help of a pulley simple machine. The hook attached at one end of the reel is a wedge. Hence, a fishing rod is a compound machine that is formed by merging three simple machines together, namely a lever, a wedge, and a pulley.
Escalators are yet another example of a compound machine. An escalator is made up of two simple machines, namely, a pulley and an inclined plane. The mechanism that helps the escalator belt move comprises a pulley simple machine, while the steps of the escalator are a modified version of inclined planes.
A shovel is a compound machine that is a combination of a wedge and a lever simple machine. The arm of the shovel acts as a third-class lever, while the tip of the shovel is a wedge. The lever helps the user move the shovel, and the wedge helps it penetrate the heap of soil or the ground with ease.
A crane consists of multiple simple machines, for example, a lever, a pulley, a combination of wheel and axle, etc. The pulley system helps the user pick or lift heavy loads with ease. The frame of the crane to which the pulley is attached is the lever simple machine. The tyres of the crane act as a wheel and axle combination that helps the machine move from one place to another.
A clipper is made up of two simple machines, i.e., a wedge and a lever. The handles of the clipper act as the first-class lever simple machine, whereas the blades of the clipper are an example of a wedge simple machine.
An electric fan is an example of a compound machine. It consists of a wedge simple machine and a combination of wheel and axle. The blades of an electric fan are wedge-shaped, which helps to maintain an even flow of air in the room. The rotation of the blades takes place around the hub. Hence, the rotating blades represent the wheel, while the hub acts as an axle.