What is the Pendulum in a Grandfather Clock?

Pendulums are the most recognized part of the grandfather clock. Usually made out of metal, the pendulum in a grandfather clock is responsible for the ‘tick tock’ pitch made when it swings back and forth. Metal pendulums for grandfather clocks used to be created out of brass and steel but presently, they are made out of Invar because of their almost zero expansion due to temperature changes.

A pendulum is a rod of varying lengths that hangs from its top and swings as it’s influenced by the force of gravity. When a pendulum swings, it affects the gears inside the clock. The swinging of the pendulum is a method of counting time. A pendulum includes a metal rod with a metal weight at its end, which is called a ‘bob’.

Galileo Galilei, an Italian scientist, postulated that a pendulum takes the same amount of time to make a complete swing. He also argued that the only thing that affected the swing of a pendulum was its length and the strength of gravity. Let us delve deeper into how the pendulum works.

Grandfather clock with pendulum

How do Pendulums in Grandfather Clocks Work?

Pendulums work by converting energy. Whenever the end of the pendulum is at its highest point from the ground, it has maximum potential energy. At the point when it begins moving towards the point closest to the ground, the potential energy is changed over into kinetic energy. As it climbs once more, towards its highest point, it acquires potential energy. The pendulum continuously changes energy forms as it swings to and fro.

This movement of the pendulum is called an oscillation. The time for each oscillation of the pendulum is constant.

Adjusting the Pendulum in a Grandfather Clock

Since the pendulum length influences the accuracy of the time kept by your grandfather clock, taking the time out to adjust the pendulum in your grandfather clock will help your clock keep accurate time. Regulating the pendulum on a grandfather clock is also regulating the length of the rod.

A Disadvantage of Pendulums in a Grandfather Clock

As mentioned above, the only things that affect a pendulum’s swings are its length and the force of gravity exerted on it.

The length of a pendulum should remain quite the same but that is not always the case. As it’s made of metal, pendulums are subjected to changes brought on by temperature changes – metals expand in the heat, increasing their length, and contract in the cold, shrinking the length. These changes in its length can affect how a pendulum keeps time.

One way to fix the changes to a pendulum’s length is by using compensating pendulums. These are pendulums that automatically adjust to compensate for the temperature changes.

There is no known way to fix the changes caused by variations in the force of gravity exerted on the pendulum. However, since the changes in the force of gravity were almost always minuscule, and the resulting changes to the time kept by the pendulum, the change is negligible.

What Causes a Pendulum to Slow Down?

A pendulum can be slow when it is too long. Shorter pendulums swing faster and are therefore more accurate and effective.

The pendulum in a grandfather clock can slow down and even stop when it has been moved, bumped, or even aggressively restarted. This is because the close case is at a different angle than it was before.

How Do You Fix a Grandfather Clock That Does Not Chime?

Sometimes, the clock does not chime exactly on the hour because the divergence is less than 15 minutes, adjusting the minute hand will solve it immediately.

Turning the minute hand forward to the next hour till the correct hour strikes fixes this problem also. Quite similar to adjusting the time on your wristwatch or wall clock.

How do you fix a Grandfather Clock that stops working?

The pendulum stops sometimes because the clock might have a worn-out piece or needs cleaning. Other times, it may be because the hands are touching each other. If they are touching, it means they’re stuck and so, the clock will not run.

 Therefore, when your clock stops, check that the hands are not stuck. Lubrication might be needed and the parts should be checked in case a piece is worn-out.

How to Maintain a Grandfather Clock.

Grandfather clocks, like all things antique, need proper and careful maintenance.

  • They should be kept locked indoors, away from direct sunlight and humidity. Harsh weather conditions can affect the glass and wear out the wood.
  • The clocks should be dusted and occasionally polished to keep the wood in good condition and termites away.
  • The gears in the clocks should be oiled as well.
  • The winding of the clock should be done weekly.

What are the Advantages of Owning a Grandfather Clock?

  •  Like a lot of other antiques, Grandfather clocks have great investment value. They can be auctioned off, pawned at shops, or even sold online for prices of $3,000 or more.
  • Grandfather clocks are artifacts, symbols of cultural heritage, authority, elegance, and in some cases, wealth. Owning one gives the home or establishment a touch of excellence due to its delightful aesthetic appeal.
  •  The chimes are difficult to be ignored, so, it helps to enforce order and organization in a household or establishment. Just like in the civil war era.
  • Grandfather clocks are classics. They never go out of style or trend, which makes it a lovely property to have. It is like owning a piece of history. They’re still being made today!
  • Grandfather clocks are highly accurate and can last for a long time. As long as 100 years! Outliving its owner. With proper maintenance of course.

Are There Disadvantages to Wwning a Grandfather Clock?

Like everything else with disadvantages, grandfather clocks have a handful.

  • The clock itself is thought to be creepy sometimes, because of how loud it sounds. The gears are not all silent, the winding as well and the chiming can scare folks and keep you from falling asleep sometimes.
  • Another disadvantage is the maintenance. Unlike common wall clocks or regular tabletop clocks, the grandfather clock requires a more advanced form of maintenance which can be difficult to keep up with.


The pendulum clock is a piece of history that has been around for hundreds of years and hopefully, will be around for a long time. Though it might be quite difficult to maintain in modern times, modern measures can be used to maintain them as well.

Pendulum clocks have been described as quite stressful to live in our modern times, especially because of how often they need to be wound. It’s tasking to always take your clock down and wind it to get the time.

The benefit of a pendulum for timekeeping is that it is a consonant oscillator: It swings to and fro in an exact period reliant upon its length, and opposes swinging at different rates

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