Types of Simple Machines in a Pencil Sharpener

A pencil sharpener uses simple machines together as a compound machine.
••• Jupiterimages/Photos.com/Getty Images

There are six different types of simple machines: a lever, a wedge, an inclined plane, a screw, a pulley and a wheel and axle. The effectiveness of a simple machine is in how it multiplies force, meaning there is more work output from the machine than energy put into it. This is called the machine's "mechanical advantage." Pencil sharpeners use either just a wedge or a wedge and a wheel and axle together.

Compound Machines

When a machine uses two or more simple machines, it is called a compound machine. Most complex machines use a series of simple machines. When they do, often the force applied to one simple machine is transferred to the next simple machine in a series. A pencil sharpener that uses a crank is an example of a compound machine since it uses two simple machines.


In a pencil sharpener, the blade that shaves off the wood and lead from a pencil to make a sharp point is a simple machine called a wedge. A wedge is constructed from two inclined planes put together. Other examples of wedges are knives, axes, shovels, forks and even teeth. The sharper the wedge is, the more of a mechanical advantage it has. It works by transferring the horizontal force you apply into vertical force. A small, handheld pencil sharpener is usually a simple wedge.

Wheel and Axle

A crank-type pencil sharpener employs a wheel and axle in addition to a wedge; you turn the axle by turning a crank, which then transfers the force from your hand to the wheel. The advantage of a wheel and axle is that it allows you to turn things using less force than by hand, though over a greater distance. Other examples of a wheel and axle are bicycle gears and steering wheels.

Putting It All Together

When using a handheld pencil sharpener without a crank, you are using only one simple machine -- a wedge. When using a pencil sharpener with a crank, however, you are using both a wedge and a wheel and axle. When you turn the crank, you turn the wheel, which in this case has a wedge attached to it. The force you apply to the axle moves to the wheel and then transfers to the wedge, making it easier to sharpen the pencil.

Related Articles

Why Does Rubbing Your Hands Together Make Them Warmer?
What Simple Machines Make a Wheelbarrow?
How to Make a Pulley for Children
How Do Pliers Work As a Lever?
The Advantages of First Class Levers
What Simple Machines Are Used in the Trebuchet?
How Doorknobs Work as a Simple Machine
Mechanism Description of a Manual Can Opener
The Difference Between a Pulley and a Sheave
Examples of a Block & Tackle
How to Identify Three Types of Levers
3 Types of Pulleys
Difference Between Simple & Compound Machines
What Are the Two Basic Families of Simple Machines?
How to Find the Magnitude When Force & Angle Is Given?
A Lesson to Introduce Simple Machines
How to Make a Screwdriver Magnet
Why Does Rubbing Your Hands Together Make Them Warmer?
How to Calculate the Mechanical Advantage of a Wedge
How to Convert Horizontal to Vertical Motion

Dont Go!

We Have More Great Sciencing Articles!