Dorrin K Mace, Horologost

Dorrin K Mace, Horologost
The Clock Man in a pensive moment

Monday, June 10, 2013

Why Does a Clock Tick Tock?

Why Does a Clock need to Tick-Tock

On occasion, I will have a customer stop that wants a clock that does not tick or hum or make any noise at all.  The only clock I know of that makes no noise at all is a Sun Dial and usually the people that want a “Silent” clock, do not want to bothered with learning how to calibrate and read a sun dial. 
That said, why does a clock tick-tock?  The simplest answer is the sound of the tick tock, in regards to a mechanical movement, is the escapement arresting and releasing allowing the gearing on the time (going) train of the clock to proceed at a given speed to allow for correct time keeping.  In a quartz clock the tick one hears is essentially the same idea, except in a quartz movement there is a quartz crystal that is excited with an electric coil that releases its energy every second so that the time (going) train can advance as required for correct time keeping. 
On many electric clocks the time is kept with a synchronous motor that reacts to the 110volt, 60 hertz cycles that is typical with the electric supplied to most residences in the United States. (50 hertz cycles and varying voltages occur  throughout the world, thus an electric clock purchased in Europe, may not keep correct time in the United States).  Less expensive electric clocks use a simple AC motor that runs much like every other electric motor; These cheap motors keep decent time but are not as long lasting as a synchronous motor or rotor and drive magnet set up as in the old Telechron mototized clocks.
But what is an escapement?  Simply put an escapement is (in mechanics), a device that permits controlled motion, usually in steps. In a watch or clock, it is the mechanism that controls the transfer of energy from the power source to the counting mechanism. The classic form for a timepiece, which made the mechanical clock possible, was the verge escapement, probably invented in 13th-century Europe. This consists of a crown wheel (i.e., a gearwheel shaped like a crown) driven by a weight and repeatedly checked by the action of a pair of metal pallets that alternately stop successive teeth. The pallets are mounted on a vertical shaft (the verge), and their speed of oscillating back and forth is controlled by a crossbar at the top (the foliot) with two small weights; moving the weights outward from the shaft slows the oscillations. The anchor escapement, an improvement invented in England in the 17th century, works with a pendulum and allows much smaller arcs of swing than the verge escapement with a pendulum. In the anchor escapement the pallets are in the shape of an inverted anchor, lying in the same plane as the wheel. Many improvements have since been made in escapements, most significantly the concept of detachment, where the escapement, while providing energy for the oscillator, is as detached from it as possible to allow the oscillator to swing as freely as possible

So why does a clock tick tock?  On a mechanical clock this is the sound of metal on metal (the verge and the escape wheel), on a quartz clock this is the sound of the time (going) train gears advancing.  Some clocks have wooden cases that act like the sound boards in musical instruments and amplify the sound of the escapement;  Additionally, the acoustics of a room can affect how loud or soft the escapement sound is perceived.

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