Pendulum Clock Adjustment

Pendulum clocks were invented by the Dutch physicist Sir Christiaan Huygens in 1656. He was led to this idea by Galileo who investigated the properties of pendulums. Also known as 'Grandfather Clocks', these were the timekeeping devices used throughout the world for more than three hundred years until the arrival of modern electronic timekeeping devices. They are the true grandfathers of time clocks and are used today for their aesthetic value. There is something very elegant about grandfather clocks with their old world charm and simplicity of design.

Principle Behind Pendulum Clock Adjustment

The pendulum clock mechanism is quite fascinating to study. In their time, they were the most accurate time keepers. For any clock to work, there has to be an element which maintains its periodic motion consistently to keep an accurate measure of time. The pendulum qualifies for this job because of its property of isochronism. The period of a pendulum's oscillatory motion will remain the same, irrespective of the size of swing and is only dependent on its length. However, this property remains true only when the pendulum swing makes it deviate by four to six degrees. The time period of a pendulum is directly proportional to the square root of its length. By varying the length over which the pendulum bob swings, you can adjust the time period.

How to Adjust a Clock Pendulum?

Before adjustment, you must study how much is the clock deviating from standard time. If it is a fraction of a minute or a few minutes, you shouldn't really bother adjusting, as the accuracy of these clocks is limited to a few minutes. However, if it is substantially deviating from the standard time, you need to go for the adjustment. Just note down the number of minutes by which your clock is deviating. Determine whether it's faster or slower than the correct time as you will have to make adjustments accordingly.

How to Speed it Up?

If you find that the clock has gone slower than the right time, you need to speed it up. Before you go ahead with the adjustment, bring the pendulum to a halt and locate a nut at the end of the pendulum's swinging bob. This is the adjustment nut. Since the clock is going slow and the period of the pendulum is directly proportional to its length, to speed it up, you'll need to shorten the length through nut adjustment. To do that, turn the nut towards right or clockwise. Every turn will shorten the time period by a short length of time. Just adjust it by one whole turn and see how much change is seen in the time shown. That will give you an idea about calibration of the pendulum. Then calculate the number of turns that you will have to make, to set it right and adjust accordingly. Set the pendulum back in motion.

How to Slow Down the Clock?

An adjustment to slow it down, is exactly opposite of the procedure to speed it up. You turn the adjustment nut anticlockwise to increase the bob length which will lengthen the period of the pendulum and slow the clock down, to conform with the right time. Test the turn calibration first and calculate the number of turns needed for rectifying the deviation. Adjust accordingly and get your clock to show right time again.

The beauty about the pendulum clock is that it is entirely driven by gravity and is driven by stored gravitational potential energy! The simplicity of its design is really inspiring.