Glossary Of Terms
A
Amplitude
When the balance wheel is impulsed, the arc described is measured. This is used as an indication as the health of the movement, similar to a heartbeat. Too
little and the watch will not keep time, too much and the watch will gain excessively.
The correct amplitude post overhaul should be:
- 270-280 degrees in the pendants.
- 300-320 degrees in the dials.
The amplitude is lower in the pendant position due to friction. In this position the balance staff is running on 2 pivot lengths, as opposed to the
dial position, when it is then running only on the pivot tip.
Automatic winding (or self-winding)
An automatic watch is wound by the movement of the wearer's wrist. This movement causes a weight inside the watch to rotate backwards
and forwards. The weight is connected by a gear train to the barrel arbour, which is hooked to the mainspring, thus winding it keeping
it in constant tension.
The mainspring needs to be wound 25-30 times to reach its full potential. An automatic watch that is not worn for 3-4 days will have to be wound manually
to start it working, after which time regular wearing will keep it fully functional.
The mainspring on automatic movements differs from a manual movements mainspring. On the end of the spring is a 'bridal'. A tail attached to allow the
spring to slip inside the barrel once it has reached its fully wound position. The tension of this bridal is crucial, too little and the spring will
slip down, wasting power, too much and the spring will bind causing it to snap.
This device allows the watch to be wound continuously, contributing to the myth of 'over winding'.
B
Beat Error
An anchor escapements travel is controlled by 2 pins positioned either side of the pallet fork arm. The function of these briefly is to keep the
fork within the working range of the escape wheel teeth and the pallet forks' jewelled stones. Thus allowing the wheel to be locked and unlocked,
allowing the watch to work correctly.
The locking and unlocking impulses the balance wheel via an impulse pin, sending the wheel on an arc. This is controlled by the hairspring, its return is caused
by the spring contracting, picking up impulse from the pallet fork to send the wheel in the opposite direction.
To operate correctly the impulse must occur at exactly the same place on the return arc. This is achieved by ensuring that when at rest, the pallet fork sits
equidistant between the banking pins. Any error in this is indicated by the timing machine as a beat error, and must be adjusted until exact to ensure efficient
unning of the watch.
Breathe
This is a term for the expansion and contraction of the hairspring. When breathing correctly, the spring is working at it's optimum efficiency.
Bridges
Any movement plate secured by a minimum of 2 screws.
C
Chronograph
When designed and executed well, one of the most impressive of movement complications. It is a system for recording elapsed time.
The centre seconds chronograph recording hand can be started, stopped and reset independently of the ordinary timekeeping of the watch.
The time elapsed in minutes and hours as well as seconds can be shown simultaneously on the dial, via subsidiary recording dials.
Chronometer
A watch with Chronometer on the dial means that the watch movement (be it mechanical or quartz) has been tested at one of the
Swiss testing institutes. The Swiss Official Chronometer Control. {C.O.S.C.}
Each movement's performance under varying conditions is recorded, and expected to maintain time to within -4 to +6 seconds per day.
The conditions experienced by the movement range from extreme heat to extreme cold, 5 positions, and a full power run down {mechanical only}
to test the watches power reserve. This should be in excess of 43 hours.
Cock
Any retaining device secured by 1 screw.
Curb Pins
Curb pins regulate the expansion and contraction of the hairspring. They are attached to the regulater, which can be moved to allow the watch to lose or gain.
D
Diving watch
A watch that is water resistant to 200M. Has a one way rotating bezel and a screw-on crown and back. Has a metal or rubber strap (not leather). Has a sapphire crystal and possibly, a wet-suit extension.
E
Endshake
The amount of movement of a wheel or component between two plates.
Escapement
This is the most delicate and important part of any mechanical movement, responsible for the accuracy of timekeeping. The most commonly used escapement today is The
Anchor Escapement. It regulates the power release from the mainspring via the train.
F and G
'Going Side'
The timekeeping module of the movement before complications are added.
H
Hairspring Stud
This is what attaches the hairspring and balance assembly to the balance cock.
Hammer
This is a sprung lever which hits the heart shaped cams of the chronograph recording wheels to return them to zero.
Heart-shaped Cam
These are located on top of the recording wheels. As the name suggests they are heart shaped, with a flat opposite the point.
When the hammer is located against the flat, the hands are placed in the zero position.The heart shape allows the hammer to hit
and run smoothly to the flat almost instantly.
I and J
Jewels
Jewels are the bearings in which the delicate pivots of the movement wheels run in.
Their purpose is to reduce friction and wear. They are made of synthetic ruby, and the modern variety are a push fit into the plates of the movement.
On some older watches they were rubbed in. literally laid in the plate, and the hole edge burnished over, or 'rubbed in'.
They have been improved over the years and are now extremely hard and enduring. More expensive watch movements are 'jewelled' from the barrel to the balance.
All of the automatic work, date work, and complications would be expected to be jewelled on an expensive watch i.e. Cartier, Breitling, Rolex etc.
The top of the jewel is bevelled to allow an oil sink to trap oil and lubricate the pivot, while the underside is machined flat to effectively control end shake of
the wheel with the minimum resistance The jewels' hole is 'olived', cut convexly to further reduce friction. As a general rule the more jewels the watch has the higher
quality it will be.
Jump hour
A watch where the hour hand is removed and replaced by an aperture in the dial, the drive to the hour hand causes a disc to revolve once every 12 hours. This disc
has the numbers 1 to 12 printed on it and as the minute hand approaches the 60-minute position the disc "jumps" to the next hour reading.
Initially (as with all complications) seen on pocket watches, it first appeared on watches in the 1920s. It almost reached mass production in the 1930s with a series
of Prince watches made by Rolex but has never been made in large quantities. For this reason any watch with a Jump Hour facility is a rarity.
K, L and M
Manual winding
A manual must be wound once a day to maintain optimum power reserve. It has a finite running time, generally 40 hours.
The mainspring on this type of movement ends with a hook, which when fully wound locates on a ridge machined into the barrel wall.
The two types of mainspring are not inter changeable.
Mechanical movement
The mechanical movement is powered by a mainspring. This is contained within a toothed barrel, and forms the beginning of the train of wheels
leading to the escapement and balance. The balance being the final wheel in the train and the means of regulation.
Mechanical Movements are far more expensive to design and produce. The more complications incorporated, the more expensive they become, i.e.
day date, chronograph, moonphase, perpetual calendar etc.
Most high quality expensive watches use the mechanical movement, some can contain up to 300 moving parts, which is why they are left to experienced,
qualified watchmakers to repair.
Moon Phase
A watch with a subsidiary dial, usually at the "6" position where an additional disc, showing a facsimile of the moon, makes one revolution each 29½ days.
The Moonphase is usually combined with a simple calendar that shows the date, the day and the month.
N, O and P
Perpetual Calendar
The early "calendar" watches, dating from the 16th century, were equipped with a mechanism giving the day, date and month in addition to the hour. In a calendar
watch, the days and months follow sequentially but the same cannot be said of the dates which are either 28, 29, 30 or 31 depending on the month and whether it is
leap year or not. In a "simple" calendar watch, it is necessary to correct the date five times during the year, i.e. the first day of March, May, July, October and December.
Abraham-Louis Breguet is usually credited with having invented the mechanism that made these corrections automatically. His invention led to the modern "perpetual calendar"
watches, as opposed to "simple calendar" timepieces. These models are based on the Julian calendar rather than the Gregorian calendar in use today. As a result, leap years
are not deleted at the end of three out of four centuries, thus making it necessary to correct the watch three times in 400 years.
Regarding leap years, February 29 has been deleted in the years 1700, 1800 and 1900. It WAS NOT deleted in 2000 but will be in 2100, thus today's ads for perpetual
calendar watches are right in their claims that these models will not have to be corrected for over a century. The actual duration of a year is 365.2422 days. The perpetual
calendar counts the year as having 365.25 days while the simple calendar counts 12 x 31 = 372 days making it necessary to remove 6 or 7 days every year.
Perpetual calendar watches feature, in addition to the base movement, a sophisticated additional mechanism (typically constructed on the dial plate) comprised of various gears
and cams that operate the indicators.
Most perpetual calendars have additional features, such as moonphase indicators and leap year indicators, each additional feature adds both to the cost of manufacture and to
its desirability.
Perpetual calendars are almost always self winding and, if worn constantly, are one of the most useful of all complications; this is why, despite the fact they are certainly
the most popular of all complications, they remain the most sought after for regular use. In recent years some companies have brought perpetual calendars to the high middle
priced market and even made them in steel cases, nevertheless all perpetual calendars are highly desirable despite their price.
Q
Quartz movement
The quartz movement is powered by a battery or a cell. The cell replaces the main spring as the motive force. Power is supplied to the going train, calculated to turn
the hands once an hour respectivley.
A current is passed through the quartz crystal, of known resonance {32,768 MHz}. The integrated circuits microprocesser, regulates the timekeeping against the crystal,
periodically adjusting the rate of gain or loss, to obtain optimium accuracy.
Extra complications can be added to quartz watches, but they are generally mechanical, driven from the train or
regulated by the crystal, i.e. chronograph, date, digital display etc.
R
Repeater
These are watches where an additional mechanism is operated by means of a slider or push button; this mechanism then tells the time by means of a series of hammers and gongs.
Initially designed to enable the wearer to tell the time in the dark, they were always the most complex of watches and were the most difficult to miniaturize to fit into
a wristwatch. There are various types of repeaters. Quarter-repeaters: sounding a single low note for each of the hours and a "ding-dong" for each of the quarters; five-minute
repeater: striking the hours, quarters and five-minute periods after the quarter; whilst minute-repeaters strike the hours, quarters and minutes; Grande Sonnerie (grand strike):
striking the hours and quarters automatically and repeating when a push-piece is pressed down; chiming repeater: in which the quarters are struck on three or four gongs of different pitch.
As with all complications, the more features a watch has, the more valuable it is and so minute repeaters are by far the most desirable.
S
Shock resistance
This refers to the watches ability to withstand an irregular impact, outside those expected in ordinary wear. The two main systems used are Kif and Incabloc.
The balance staff pivots run in jewels, which are held in a setting that is secured by means of a spring. This allows the impact to be absorbed, a
nd the whole assembly to move in any direction, protecting the delicate staff, which in some cases can be as small as 0.25 of a millimetre. More information
can be found about this on our technical page.
T, U, V, W, X, Y and Z
Tourbillon
A device invented by Abraham-Louis Breguet to eliminate errors of rate in the vertical positions. It consists of a mobile carriage or cage carrying all the parts of the escapement,
with the balance in the center. The escape pinion turns about the fixed fourth wheel. The case usually makes one revolution per minute, thus annulling errors of rate in the
vertical positions.
The Tourbillon is a mechanism that even in its most conventional version, is extremely hard to manufacture. At a time when all tools were still somewhat primitive, the production
of a Tourbillon watch was a confirmation of competence far more appreciated than the diplomas awarded by the best watchmaking schools.