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From ‘alarm watch’ to ‘zodiac’…

The following pages are a glossary of terms associated with horology, watches and watchmaking.




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O


Observatory Chronometer


An observatory-tested precision watch that obtained the relevant rating chronometer certificate.


 
Oscillation


Complete oscillation or rotation movement of the balance, formed by two vibrations. When a pendulum or balance oscillates it moves between two extreme positions (A' and A''). The movement from one of these positions to the other and back equals one oscillation. Usually a balance produces 9,000 oscillations an hour, equivalent to 18,000 vibrations. 1 oscillation = 2 vibrations


 
P


Pallets


Device of the escapement transmitting part of the motive force to the balance, in order to maintain the amplitude of oscillations unchanged by freeing a tooth of the escape wheel at one time.


 
Pillar-Plate or Main Plate


A metal platform having several tiers for the gear train. The base plate of a movement usually incorporates the dial and carries the bearings for the primary pinions of the “first floor” of a gear train.


 
Pinion


Combines with a wheel and an arbor to form a gear. A pinion has less teeth than a wheel and transmits motive force to a wheel. Pinion teeth (normally 6 to 14) are highly polished to reduce friction to a minimum.


 
Pivot


End of an arbor turning on a jewel support. As their shape and size can influence friction, the pivots of the balance-staff are particularly thin and, hence, fragile, so they are protected by a shockproof system.


 
Polished Finish


Brilliant metal surface obtained on the watch case with fine abrasive. Compare with brushed finish.


 
Power Reserve


Duration, in hours, of the residual functioning autonomy of a movement after it has reached the winding peak. The duration value is displayed by an instantaneous indicator: analogue (hand on a sector) or digital (through a window). The related mechanism is made up of a series of gears linking the winding barrel and hand. Recently, specific modules were introduced which may be combined with the most popular movements.


 
Precision


Accuracy rate of a watch, a term difficult to define exactly. Usually, a precision watch is a chronometer of which accuracy-standard is certified by an official watch-rating bureau.


 
Pusher, Push-Piece or Push Button


Mechanical element mounted on a case for the control of specific functions. Generally, pushers are used in chronographs, but also with other functions.


 
PVD


Abbreviation of Physical Vapour Deposition, a plating process consisting of the physical transfer of substance by bombardment of electrons. Though PVD coatings are typically only a few microns thick the molecules bond to the surface of the metal in such a way that they are nearly impossible to remove once applied. It reduces wear of bracelets, crowns, bezels and virtually eliminates reflective glare.


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Q


Quartz


Timekeeping’s technical revolution found its way to the world’s wrists in the late 1960’s. This was principally a Swiss invention (the first working quartz watches were made by Girard-Perregaux and Piaget in a Swiss joint venture) but it was the Japanese firms, primarily Seiko, who were the first to see the advantages of the new technology and came to dominate the market. The quartz movement uses the famously stable vibration frequency of a quartz crystal subjected to the electronic tension (usually 32,868Hz) as its norm. The Malvern Chronograph has the renowned Ronda Calibre 5040D, as its quartz movement.


 
Quartz Movement


A movement powered by a quartz crystal. Quartz crystals are very accurate. They can be mass produced which makes them less expensive than most mechanical movements which require a higher degree craftsmanship.


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R


Ratchet Wheel


Toothed wheel prevented from moving by a click pressed down by a spring.


 
Regulating Unit


Made up by balance and balance spring, governing the division of time within the mechanical movement, assuring its regular running and accuracy. As the balance works like a pendulum, the balance spring's function consists of its elastic return and start of a new oscillation. This combined action determines the frequency, i.e. the number of vibrations per hour, and affects the rotation speed of the different wheels. In fact the balance, by its oscillations, at every vibration (through the action of the pallets), frees a tooth of the escape wheel (see escapement). From this, motion is transmitted to the fourth wheel, which makes a revolution in one minute, to the third and then the centre wheel, the latter making a full rotation in one hour. However, everything is determined by the correct time interval of the oscillations of the balance.


 
Regulator


Regulating the functioning of a movement by lengthening and shortening the active section of the balance spring. It is positioned on the balance-bridge and encompasses the balance spring with its two pins near its fixing point on the bridge itself. By shifting the index, the pins also are moved and, by consequence, the portion of the balance spring capable of bringing the balance back is lengthened or shortened by its elastic force.

The shorter it is, the more reactive it tends to be and the more rapidly it brings the balance back and makes the movement run faster. The contrary happens when the active portion of the balance spring is lengthened. Given today's high frequencies of functioning, even slight index shifts entail daily variations of minutes. Recently, even more refined index-regulation systems were adopted (from eccentric to micrometer screws) to limit error margins to very few seconds per day.


 
Regulator display


A Regulator display separates the minute and hour hands onto a separate axial & sub-dial. Before the advent of more modern methods of checking for the accuracy of a watch, watchmakers used a regulator clock where the hour, minute and second hands are operated separately, to check their work.

More recently, mechanical regulator watches were used during Second World War night-time bombing missions when greater precision was essential


 
Retrograde


Said of a hand that, instead of making a revolution of 360º before starting a new measurement, moves on an arc scale (generally of 90º to 180º and at the end of its trip comes back instantaneously. Normally, retrograde hands are used to indicate date, day or month in perpetual calendars, but there are also cases of retrograde hours, minutes or seconds. Unlike the case of the classical indication over 360º the retrograde system requires a special mechanism to be inserted into the basic movement.


 
Rotating Bezel


A bezel that can be turned. Different types of rotating bezels perform different time keeping and mathematical functions.


 
Rotor


The rotor is the component that keeps an automatic watch wound. The kinetic motion of this part, which contains a heavy metal weight around its outer edge, winds the mainspring.


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