Simple Machines

The six most common Simple Machines

Pulley

A grooved circular disk (or disks) that guide a rope or cable pulled around its perimeter. With a single pulley engineers can change the direction of an applied force, such as pulling a rope down to lift a weight up. However, using a combination of pulleys in a pulley system can change both the amount and direction of the applied effort. Engineers design large machines, like cranes, bulldozers and elevators, with a system of pulleys to manipulate huge loads with a little force supplied by a relatively small motor.

Screw

An inclined plane that is wrapped around a cylinder. Engineers use screws in a variety of ways, including fasteners that are used to attach wood or metal; lifting screws that are used to lift heavy objects and dig holes; and bolts that are used with nuts to keep things together.

Lever

A long beam that rests on a point or support called a fulcrum. By positioning the fulcrum close to a heavy object and applying an effort from far away, levers can be used to lift enormous loads with ease. The object being moved by the lever is often called the load, or output force, while the force applied to the lever is called the effort, or input force. Crowbars are a commonly-used lever that help workers and carpenters easily extract nails from wood.

Wedge

An object that tapers to a thin edge and forces a substance apart. It can be used to split things apart, such as an ax, or to hold things, such as a doorstop. Engineers design modern cars and jets using the principle of a wedge to help them cut through the air by including a pointed wedge at the front.

Wheel & Axle

Composed of a circular wheel directly connected to a circular shaft or axle, this device rotates around the common axis and has the ability to increase a rotational force instead of a linear force. Engineers commonly refer to a rotational force as torque and use this simple machine to design and create the steering wheel, jet engine, mechanical gears, and even doorknobs.

Inclined Plane

A flat, sloping surface that is used for raising or moving heavy objects from one place to another. Inclined planes are used to lift loads that would otherwise be too heavy to lift straight up. The angle or the steepness of the inclined plane determines how much effort is required to move an object. The steeper the angle, the more effort is required. We see inclined planes used in ramps and switchback roads.

The simple machines used by ancient engineers to construct the pyramids in Egypt and the Colosseum in Rome are the same ones used by engineers today to build roller-coasters, skyscrapers and bridges in our modern world. We encounter simple machines in our everyday lives in devices like crowbars, wheelbarrows and highway ramps.

These simple machines leverage the unique phenomenon of mechanical advantage of the design and then engineers combine multiple simple machines to create more advanced tools like cars, bicycles, medical devices and 3D printers.