In
addition to their exterior beauty, watches are also an incredible
feat of engineering and craftsmanship. Many complicated parts must
all work in tandem in order to not only tell time, but perform the
myriad other functions that many of today's watches perform. This
section contains an overview of the major parts of a watch, as well
as an explanation of how watches operate.
How
a Watch Works
Watches essentially tell time by the integration of three main components:
an energy source, a time regulating mechanism and a display. The
energy source can be electronic (as in a battery) or mechanical
(as in a wound spring). A watch's main timekeeping mechanism is
called its movement. Today's watches fall into two categories: Mechanical
movements and Quartz movements. Here's a breakdown of how each type
of movement works:
Mechanical
(Automatic) Watches
The
traditional mechanical watch is made up of about 130 parts assembled
in the three main parts, which are the source of energy, the regulating
parts and the display.
Automatic
mechanical movements mark the passage of time by a series of gear
mechanisms, and are wound by the movement of your wrist as you wear
it. The gear train then transmits the power to the escapement, which
distributes the impulses, turning the balance wheel. The balance
wheel is the time regulating organ of a mechanical watch, which
vibrates on a spiral hairspring. Lengthening or shortening the balance
spring makes the balance wheel go faster or slower to advance or
retard the watch. The travel of the balance wheel from one extreme
to the other and back again is called oscillation. A series of gears,
called the motion work, then turns the hands on the watch face,
or dial.
The number of
component parts is much higher in so-called complicated watches
(date, phases of moon, fly-back hand, etc.). The "ébauche"
(about 60 parts) fitted with the regulating and certain other parts,
forms the movement, in other words the internal mechanism of the
watch, which makes it possible to maintain a constant tension in
the spring once it has been wound manually or automatically (by
movements of the wrist) and to regulate the display by means of
the hands (hours, minutes, seconds). A watch is said to be finished
when the movement has been fitted with a dial, hands, and case.
A
mechanical watch
1) Barrel/mainspring providing the power
2) Gear train, transmitting the power
3) Escapement, distributing the impulses
4) Balance wheel & hairspring, oscillating, making the
division of time
5a) Winding stem, for manual winding and setting
5b) OscillatingwWeight, for automatic winding
6) Dial train, activating the hours, minutes, seconds hands
The combination of these two technologies recently brought on
a new type of watch movement running like a traditional quartz
movement but getting its energy the same way as in a self-winding
mechanical movement (Self-winding watch with the quartz precision).
Its working principle is simple and however revolutionary: an
oscillating weight streches the mainspring which release starts
a micro-generator converting the mechanical energy into electrical
power. This power is then accumulated in a capacitor. The system
works later as a traditional quartz watch, meaning that the integrated
circuit controls the power supply and provides the impulses to
the stepping motor.
Quartz
Crystal Watches
Quartz watches work with a series of electronic components, all fitting
together in a tiny space. Rather than a wound spring, a quartz watch
relies on a battery for its energy. The battery sends electrical energy
to a rotor to produce an electrical current. The current passes through
a magnetic coil to a quartz crystal, which vibrates at a very high
frequency (32,768 times a second), providing highly accurate timekeeping.
These impulses are passed through a stepping motor that turns the
electrical energy into the mechanical energy needed to turn the gear
train. The gear train turns the motion work, which actually moves
the hands on the watch dial.
In an
analog quartz watch, the heart of the watch is the integrated circuit,
made up of a large number of electronic components grouped together
on a base of only a few square millimeters.
The source of energy consists of a miniature battery which lasts several
years. The time is divided by a quartz oscillator which is made to
vibrate by the energy supplied by the battery. Quartz watches are
extremely accurate thanks to their high frequency of vibrations (32
kHz); their annual variation is only about one minute per year, equivalent
to less than a second a day.
In this field there are two main kinds of products:
1) watches with an analog display (hands)
2) watches with digital display; this is fitted with liquid
crystals which receive, directly from the integrated circuit, the
impulses needed to display the time. So there is no mechanical transmission.
An
electronic (quartz) watch
1) Battery, providing the power
2) Integrated circuit, controlling the quartz and the stepping
motor
3) Oscillating quartz, dividing the time
4) Trimmer, regulating the frequency
5) Stepping motor, transforming the electrical impulses into
mechanical power
6) Gear train, activating the hours, minutes, seconds hands
7) Analog display
These two types of products are sometimes combined together in the
same finished watch (double display, particularly useful for measuring
short time intervals).
Watch Parts
Watches contain many parts that work together to tell time, as well
as perform other useful functions. These could include a chronograph,
altimeter, alarm, day/date calendar, phases of the moon, slide-rule,
etc. Here are descriptions of the major internal and external parts
and their functions.
External Watch Parts
Crystal
The cover over the watch face is called the crystal. There are three
types of crystals commonly found in watches: Acrylic crystal is an
inexpensive plastic that allows shallow scratches to be buffed out.
Mineral crystal is composed of several elements that are heat-treated
to create an unusual hardness that aids in resisting scratches. Sapphire
crystal is the most expensive and durable, approximately three times
harder than mineral crystals and 20 times harder than acrylic crystals.
A non-reflective coating on some sport styles prevents glare.
Hands
A watch's hands are the pointing device anchored at the center and
circling around the dial indicating hours, minutes, seconds and any
other special features of the watch. There are many different types
of hands:
• Alpha:
A hand that is slightly tapered
• Baton: A narrow hand sometimes referred to as a 'stick
hand'
• Dauphine: A wide, tapered hand with a facet at the center
running the length of the hand
• Skeleton: Cutout hands showing only the frame
• Luminous: Hand made of skeleton form with the opening
filled with a luminous material
Bezel
The surface ring on a watch that surrounds and holds the crystal in
place is called the bezel. A rotating ratchet bezel moves in some sport
watches as part of the timing device. If rotating bezels are bi-directional
(able to move clockwise or counter clockwise), they can assist in calculations
for elapsed times.
Crown
The nodule extending from the watchcase that is used to set the time,
date, etc. is called the crown. Most pull out to set the time. Many
water-resistant watches have crowns that screw down for a better water-tight
seal.
Dial
The watch face that contains the numerals, indices or surface design
is called the dial. While these parts are usually applied, some may
be printed on. Sub-dials are smaller dials set into the main face of
the watch. These can be used for added functions, such as elapsed times
and dates.
Case
(or Watchcase)
The watchcase is the metal housing that contains the internal parts
of a watch. Stainless steel is the most typical metal used, but titanium,
gold, silver and platinum are also used. Less expensive watches are
usually made of brass that has been plated with gold or silver.
Bracelet
A bracelet is the flexible metal band consisting of assembled links,
usually in the same style as the watch case. Detachable links are used
to change the length of the bracelet. Bracelets can be made of stainless
steel, sterling silver, gold, or a combination.
Strap
A strap is simply a watchband made of leather, plastic or fabric.
Internal Watch Parts
A watch's main timekeeping mechanism is called its movement. Today's
watch movements fall into two categories: Automatic mechanical or quartz.
Automatic mechanical movements mark the passage of time by a series
of gear mechanisms. Most automatic movements are wound by the normal,
everyday movement of your wrist, which charges the watch's winding reserve.
Quartz movements are powered by a battery and do not stop working once
removed from your wrist.
Balance Wheel
The regulating organ of a watch with a mechanical movement that vibrates
on a spiral hairspring is called the balance wheel. Lengthening or shortening
the balance spring makes the balance wheel go faster or slower to advance
or retard the watch. The travel of the balance wheel from one extreme
to the other and back again is called oscillation.
Gear
Train
This series of small gears in both quartz and mechanical movement watches
is responsible for transmitting the power from the battery (in a quartz
watch) or spring (in a mechanical watch) to the escapement, which distributes
the impulses that mark the time.
Escapement
This part of the watch restricts the electrical or mechanical impulses
of the gear train, metering out the passage of time into equal, regular
parts.
Motion Work
The motion work is a series of parts inside a watch that receive power
from the escapement and gear train, which distribute and generate
the watch's power. The motion work is responsible for actually turning
the watch's hands.
Mainspring
The mainspring is the energy source responsible for powering the watch
movement (as opposed to a battery in a watch with a quartz crystal movement).
The spring is wound, either manually (using the winding stem) or automatically,
by the motion of the wearer's wrist. Potential energy is stored in the
coiled spring, then released to the gear train which transmits the power
to the escapement and motion work, which turns the hands on the watch
dial.
