The Basics of the Pendulum Clock: The Grandfather Clock
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For 270 years, until the invention of the quartz clock in 1927, Pendulum clocks remained the world standard for accurate timekeeping.
(A quartz clock uses an electronic oscillator, regulated by a quartz crystal to keep time. This crystal oscillator generates a signal with a precise frequency, making the quartz clock more accurate than most mechanical clocks. Quartz clocks have become progressively more popular since the 1970s. An electronic oscillator is an electronic circuit that produces a repeting electronic signal. Oscillators are designed to produce a high-power AC output from a DC supply. An electronic circuits are closed paths formed by the connection of electronic parts through which an electric current flows. An electronic circuit can usually be categorized as an analog, digital, or a mixed-signal circuit.)
used as standards through World War 2.
(The most accurate experimental pendulum clock to date (2007) may be the Littlemore clock, built by Edward T. Hall (See below) in the 1990’s, the Littlemore clock, the most accurate mechanical clock when air pressure changes.
Edward Thomas Hall
Born: May10,1924 in London, England
Died: August 11, 2001 (aged 77)
Residence: Oxford
Nationality: British
Fields of Study: Archaeological science, Alma mater, New college, Oxford (Chemistry)
Notable awards: Commander of the Order of the British Empire, Fellow of the British Academy)
All mechanical pendulum clocks have five internal parts.
1. A power source; either a weight on a cord that turns a pulley, or a mainspring.
(A mainspring is a spiral spring of metal ribbon that is the power source in mechanical watches and some clocks. By turning a knob or key, and winding the timepiece, energy is stored in the mainspring. This is accomplished by twisting the spiral mainspring tighter. The force of the mainspring then turns the clock's wheels as it unwinds, until the next winding is needed. The adjectives ‘wind-up’ and ‘spring-wound’ refer to mechanisms powered by mainsprings, which also include kitchen timers, music boxes, and wind-up toys.)
2. A gear train (wheel train) that steps up the speed of the power so that the pendulum can use it. A gear train is a set or system of gears arranged to transfer torque from one part of the system to another.
(Torque, also called moment or moment of force. Moment is the tendency of a force to rotate an object about an axis, fulcrum, or pivot point. Torque can be thought of as a twist. In more basic terms, torque measures how hard something is rotated. As an example, a wrench is trying to twist a nut or bolt. The amount of "twist" (torque) depends on three forces, the length of the wrench, the force used on the wrench, and how well you are pushing the wrench in the proper direction.
A striking train strikes a chime on every hour, with the number of strikes equal to the number of the hour. More complex striking trains are called chiming clocks, strike on the quarter hours, and may play simple melodies, usually Westminster Quarters.
A striking clock is a clock that sounds the hours clearly on a bell or warning bell. The striking clocks were initially more vital than their clock faces. Many did not have clocks faces or dials. “The development of mechanical clocks in Europe was motivated by the need to ring bells upon the canonical hours to call the community to prayer. The earliest known mechanical clocks were large striking clocks installed in towers in monasteries or public squares, so that their bells could be heard far away. A typical striking clock will have two gear trains, because a striking clock must add a striking train that operates the mechanism that rings the bell in addition to the timekeeping train that measures the passage of time.”
The Westminster Quarters is the most common name for a song used by a set of clock bells to strike the hour. It is also known as the Westminster Chimes or the Cambridge Chimes from its place of origin, the Church of St. Mary the Great, Cambridge, England.)
3. An escapement that gives the pendulum accurately timed impulses to keep the pendulum swinging. (Already explained in brief in the longcase clock page essay.)
4. The pendulum, a weight on a rod. (Explained in the Clock Terms page.)
5. An indicator or dial that records how often the escapement has rotated, consequently how much time has passed, usually a traditional clock face with rotating hands
(A clock face is the part of a clock that displays the time through the use of a fixed numbered dial or dials and moving hands. The dial or clock face is numbered 1 through 12, indicating the hours in a 12-hour cycle. The dial has a short, hour hand, which makes 2 revolutions of the dial a day. A longer, minute hand makes one revolution each hour. The clock face may also contain a second hand which makes one revolution per minute.)
More to come.
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