The Mechanics Behind Watches and Clocks

Icon June 2, 2021 11:28 AM

Have you ever looked at a clock or a watch and wondered what makes it tick? It's really quite simple. Inside of watches and clocks, there are a bunch of gears that work together to measure the time. The parts inside of a clock might look really detailed, but in fact, the timekeeping function of mechanical clocks can be explained with only five elements!

Energy Source

All machines need a source of energy to work, including clocks! For clocks, the energy is stored within a spring. When the clock is wound up, energy is transferred into the spring, and then the energy is released into the clock as the spring unwinds.


There's an interconnected series of gears, called a train, inside every clock. The energy released from the spring makes a gear turn, and this makes the gear it's connected to turn, and so on through the whole train.


The escapement is connected to the gear at the end of the train. The escapement's role is similar to that of a turnstile: It allows one gear tooth to pass through at a time, just like a turnstile allows one person to pass through a gate at a time. This forces the gears to turn at a regular pace instead of using up all of the energy from the spring at once.

  • Fun fact: The escapement is what creates the ticking sound of a clock! It's the sound of the escapement stopping a gear tooth.


Just like the name suggests, the controller controls the rate of the escapement. After each gear tooth passes through the escapement, the controller is pushed ever so slightly one way or the other, which keeps it going. A common controller is the pendulum you see sometimes on an old clock. It's a hanging weight that swings back and forth at a steady rate.


An indicator is a part of a clock that tells the time. Indicators are often called clock hands, such as the hour hand and the minute hand, which indicate to us what time it is. Some clocks even have a bell indicator that announces every hour that passes.

Additional Resources

  • Clock Facts for Kids: This encyclopedia page is full of facts about how analog clocks work and how telling time has evolved over the centuries.
  • How Does a Mechanical Clock Work? This article covers an overview of how clocks work.
  • Clocks for Kids: Britannica Kids covers the history of clocks and how they work on this page.
  • Facts About Clocks: This page includes videos and facts about how clocks work and how to tell time.
  • How Do Water Clocks Work? You've heard of sundials, but what happens when there is no sun to tell time? This page talks about how ancient civilizations used water clocks and how they worked.
  • How Clocks and Watches Work: PBS Learning Media has a fun lesson here that can help you learn more about how the insides of a clock work together to help us tell the time.
  • Project Clock: This lesson breakdown about how mechanical clocks work includes a video and step-by-step instructions for how to make your own wooden mechanical clock.
  • How Pendulum Clocks Work: Watch videos that show how clocks work and see the mechanisms of clocks in action here.
  • How Watches Are Made: This website includes information about the materials, manufacturing, and components of watches.
  • Newton's Apple: Clocks: Learn how to make your own water clock to keep time!
  • How Clocks Work: This article is about how different inventions have helped us to tell time, like the sundial, pendulums, and atomic clocks.
  • How to Adjust an Antique Clock: If you have your own antique clock, you should know that you'll need to tinker with it every once in a while to keep it running properly. Read this page to find videos and pictures to help guide you along.
  • How Watches and Clocks Work: This page has a labeled diagram that shows all of the different parts of a clock and why they are important for making the clock work the way it does.
  • How Does a Pendulum Clock Work? Find out what a pendulum clock is, what's inside of it, and how it works.
  • How to Make Your Own Hourglass: With a few materials found around the house, you can create an hourglass to measure the passing time.
  • Why Is Tinkering Important? If you want to create your own clock, you need to start learning how to tinker. Here's why tinkering is important for learning!
  • What You Need to Know About Tinkering, Making, and Engineering: This document covers everything you may want to learn about tinkering, the kind of activity that led to the development of mechanical clocks, and how great it is for getting more invested in science.
  • STEM Family Activities Workbook: This book has a bunch of fun hands-on activities you can do with your family.