Jun
28
Filed Under (sanders) by admin
Nancy Sander asked:


There are two internal workings of the grandfather clock that I would like to discuss today, the pendulum and escapement mechanisms. These are integral to the clocks functionality and activate the beautiful chimes we hear in our homes.

As I have discussed in another article, some of the earlier long case clocks had a pendulum arch of 100 degrees. Long pendulums with such wide swings were in large open clocks usually outside. With the invention and use of the anchor escapement mechanism, the pendulum clock was able to reduce the pendulum swing radius to 4 to 6 degrees.

The introduction of the long case or grandfather clock is due to the invention of the anchor escapement mechanism. (An escapement is the mechanism in a mechanical clock that maintains the swing of the pendulum and advances the clock’s wheels with each swing. An anchor escapement is a type of escapement used in pendulum clocks.)

Most of these clocks had short pendulums to be contained within a case. As advances were made in escapement mechanisms, clockmakers were able to use longer pendulums, which had slower “beats,” but maintained the shorter swing radius. These needed less power to keep going. They had less friction and wear in the movement, and were more accurate.

Modern grandfather clocks use a more accurate variation of the anchor escapement called the dead beat escapement. The deadbeat form of the anchor escapement was initially used only in precision clocks, but due to its superior accuracy its use spread during the 1800’s to most quality pendulum clocks. Most pendulum clocks made today use it. Most of a long case clock’s height is used to hold the long pendulum, weights and the two chains attached to the weights.

Traditionally, long case clocks were made with one of two types of movements, the eight-day and one-day (30-hour) movements. Eight-day clocks are often driven by two weights, one driving the pendulum and the other the striking mechanism. Such movements usually have two keyholes on either side of the dial or clock face to wind each one.

By contrast, 30-hour clocks often had a single weight to drive both the timekeeping and striking mechanisms. Some earlier 30-hour grandfather clocks were made with false keyholes in the clock face. This was for customers who ‘wished’ the guests to their home would think that the household could afford the more expensive eight-day clock. Cable clocks are wound by inserting a special crank (called a “key”) into holes in the clock’s face and turning it. The lack of winding holes in the dial or clock face show this to be a 30-hour clock.

Other long case clocks are chain-driven and have weights suspended by chains that wrap around gears in the clock’s mechanism. To wind a chain-driven grandfather clock, the end of each chain is pulled downward lifting the weights.

Today we also have 31 day and quartz movements in some longcase or grandfather clocks.

In the early 20th century, quarter-hour chime sequences were added to long case clocks.

Most long case clocks use the seconds pendulum (”Royal” pendulum). These are about 39 inches long. A seconds pendulum takes 2 seconds to make the full swing. In 1670 the seconds pendulum was employed by William Clement in his improved version of the original pendulum clock by Christian Huygens.

Christian Huygens was credited with the invention of the original pendulum clock. He was a prominent Dutch mathematician born in 1629.He was also known as an astronomer, physicist, and horologist (Horology is the art and science of time.). He was also a writer of early science fiction. His work included many areas of study, including investigations and inventions related to time keeping and the pendulum clock. He was a fascinating man.

(An interesting factoid is that In Britain around 1855 the British ‘yard’ was defined as a specified fraction of the length of the seconds pendulum.)



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