How pendulum clocks work
As complex as the mechanisms of a pendulum clock appear, they are not any more complicated than a battery operated clock. They have been used since 1656, and over many years, clock designers have worked out methods of creating accuracy with regards to timekeeping. The Dutch astronomer, Christiaan Huygens, first suggested the use of a pendulum.
The parts of a pendulum clock are as follows: The face of the clock, an hour and minute hand, a weight, and the pendulum. There are many kinds of pendulum clocks, namely wall clocks (where the pendulum swings once every second), grandfather clocks and cuckoo clocks (where the pendulum swings once every two seconds).
A simple pendulum is basically a weight, which is attached to the end of a string. The weight hangs from a point and swings to and fro. The path that the pendulum swings along is called the arc of the pendulum. The weight stores energy, so that the pendulum clock can operate for fairly long periods of time. When you wind up a clock, you pull on a cord that lifts the weight, creating gravitational potential energy.
The amount of time it takes for a pendulum to go back and forth once is related to the force of gravity and the length of the pendulum. However, because gravity is constant on Earth, the only thing that affects this time is the length of the pendulum. The weight of the pendulum and the length that the pendulum swings in an arc does not matter. It is only the length of the pendulum that matters. Galileo discovered that a pendulum swings at a constant rate, regardless of the energy in each swing.
In an escapement (a mechanism that keeps the weight from unwinding too rapidly or unevenly), there is a gear with “teeth” in a special shape. There is also a pendulum, and attached to the pendulum is a mechanism which engages the “teeth” of the gear. Each time the pendulum swings back and forth, one tooth of the gear is allowed to pass. During this time, the gear will make a “tick-tock” sound.
It is important to remember that a pendulum will not swing indefinitely. This is why another role of the escapement gear is to let out just enough energy into the pendulum to overcome the friction, allowing it to keep swinging. To do this, the mechanism that is attached to the pendulum to release the escapement gear one tooth at a time, and the teeth on the escapement gear are specially shaped. The pendulum is given a push in the right direction by this mechanism each time through a swing. This push is the boost of energy that the pendulum needs to overcome friction, so it keeps swinging.
However, in the past, a few problems with this pendulum clock occurred, because pendulums act differently under various conditions of gravity and weather. Pendulums take a longer time to swing in lower gravity, such as on mountains. Also, they are affected by changes in the weather, because the metal holding the pendulum weight expands and contracts according to the temperature.
Today, most pendulum clocks consist of two mechanisms that allow adjustments to the pendulum according to the conditions they are in. There is a screw above the pendulum, which allows minor adjustments in the length of the cord. This adjusts the speed of the clock. It can be used if the clock is running either too slowly or too fast.
A few pendulums also have regulators, which help to avoid allowing the clock to run more slowly in warm weather or fast during cold weather. These regulators are made of brass and steel, because they expand and contract at different temperatures. They work together to keep a consistent length. When the length of the pendulum stays constant, the clock will keep time accurately instead of running slower or quicker in different kinds of weather.
Clocks play a huge role in our daily lives. The invention of the pendulum clock allowed an opportunity to keep time accurately and led to a whole new way of living life. In this modern world, clocks are sadly taken for granted, but somehow the splendour of a mechanical pendulum clock always has the power to fascinate people.
SOURCES:
http://electronics.howstuffworks.com/gadgets/clocks-watches/clock4.htm
http://www.thefreedictionary.com/escapement
http://www.essortment.com/hobbies/howpendulumclo_sfua.htm
