Rolex watch repair service



Glossary of Terms


The greatest angular displacement a balance moves - measured from the zero or rest Position to position of maximum displacement, expressed in degrees.


The oscillating element of the watch; it may be monometallic or bimetallic.


Abraham Louis, 1747 - 1823 Horological genius / inventor. The name given to the type of balance spring which has its outer coil raised above the body of the spring & curved inwards.


A watch with hands that display hours, minutes and seconds, together with an additional mechanism for measuring continuous or interrupted periods of time and set to zero independently of the watch movement.


A watch that has obtained a certificate from an official neutral testing center such as "COSC" (Controle Officiel Swiss des Chronometres) or "SOCC" (Swiss office for chronometric controls) after having passed strict precision tests for accuracy. These tests are performed in a laboratory over a minimum 15-day period. They test the movement alone, using successive daily rate figures at different temperatures and with the movement in different positions.


Dynamic Poise
Poising a balance by observing its errors on a timing machine while the watch is running at a reduced amplitude and at various positions.

French term for a movement blank, i.e. an incomplete watch movement which is sold as a set of loose parts, comprising the main plate, the bridges, the train, the winding and setting mechanism and the regulator. The timing system, the escapement and the mainspring, however, are NOT parts of the "├ębauche".

A nickel, steel alloy containing other additions such as chromium, manganese, titanium, tungsten or beryllium, which has a very low thermoelastic coefficient over the range of temperatures commonly encountered by a watch.Used in modern balances and springs, derived from the words "elasticity" and "invariable".


Provides the balance with fresh additions of energy at regular intervals, and simultaneously prevents the movement from racing ahead and expending all its energy in a few mad seconds.


Number of complete oscillations made by the balance & spring in one second.
Example: 18,000 Vibrations per hour = 2.5 cycles per second, (Also referred to as "Hertz" - 2.5Hz).


Galling is a cold welding phenomenon which can occur when uncoated stainless steel (or aluminium alloy parts), such as the threads of the case and case back are forced together. These materials owe their corrosion resistance to the ease with which they passivate, forming a thin protective oxide layer. The friction scrapes off this oxide layer from the surface asperities and exposes clean reactive metal. If the mating parts are of a sufficiently similar material, no additional activation energy is needed to cold weld them together.

Galling can occur even if the parts are brought together slowly, and it is prevented by the presence of grease or surface coatings, even if the surface coatings increase friction. It does not occur when joining dissimilar materials (for example threading 18-8 stainless into 17-4 stainless) even though both of those materials are susceptible to galling. Galling does not occur on carbon steel.


The attraction exerted by Earth on all bodies. Its value is defined by the acceleration it causes in a free falling body.


The science and study of time measurement, the art of manufacturing or repairing timepieces.


Energy transferred to the balance or pendulum to maintain it in oscillation.


Electronic procedure for fine tuning a quartz watch without modifying the specific frequency of the quartz, periodically (every 60 seconds) adapts the moment of electrical impulse to the motor, correcting the display.


A metal alloy comprised of about 36% nickel, 64% iron, having a very low coefficient of expansion. Comes from the word "invariable"


Condition when time taken for 1 vibration remains the same, regardless of amplitude.


A Synthetic material used to make a modern watch movement's bearings - These synthetic Rubies are almost as hard as diamonds. The "Jewels" reduce friction and maintain the properties of the oil longer.


Energy possessed by a body in motion.


When the amplitude of a balance wheel exceeds 315 degrees, the roller jewel may strike the horn of the pallet fork at the end of the supplementary arc.


The angular distance which the roller jewel makes contact with the pallet fork.


The average, taken over one year of all the true solar days.


An imaginary line on the earths surface passing North - South in relation to the polar axis. In 1884, the 0 meridian was fixed as a line passing North - South through Greenwich Observatory in England.


Self compensating balance spring alloy, basically nickel steel containing beryllium and other additions.


Motion of balance from one position of maximum displacement to the next and the return to original position.


Indicates the day of the week, the date, the month and the phases of the moon and Automatically allows for varying lengths of months, as well as leap years - No manual correction is necessary.


Watchmakers say that a balance is "in poise" when the balance is in neutral equilibrium, as verified on the poising tool for example. Its significance is that the center of gravity lies on the axis of rotation.


Difference between the rates of the watch in various positions.


To a watchmaker, this expression means the point of attachment of the balance spring to the collet is located in the most favorable position to ensure good performance in the vertical positions.


A timer or chronograph with a graduated dial or bezel used to indicate the number of heart beats per minute. This is done by measuring the time taken for a fixed number of beats to occur.


Crystalline silica; under certain conditions, pieces cut from quartz crystals can be maintained in rapid oscillation of very stable frequency. For this reason they are used in clocks, timing machines & many other applications.

Very popular since the 19th century. At that time, electric light and luminous dials and hands had not yet been invented. This complication sounds a tone to indicate the hours by an internal mechanism. Various types of repeater designs have been made.

  • A minute repeater sounds a low tone for each hour, two tones for each quarter hour and one high tone for each minute after the quarter hour.
  • A quarter repeater sounds one low tone for the hours and a double (high tone followed by a low tone) for the quarters.
  • A five-minute repeater sounds a low tone for the hours and five minute intervals after the hour on a higher tone.

A timer or chronograph with a graduated dial or bezel which enables you to measure a vehicles speed per hour. The figure indicated by the tachometer scale graduation is calculated on the basis of one kilometer or one mile. This is done by measuring the time elapsed over a fixed distance.


A timer or chronograph with a graduated dial or bezel which enables you to measure distance by measuring the time elapsed at a fixed speed. I.E. The speed of sound.


Electronic procedure for fine tuning a high precision quartz watch. Periodically (every 8 minutes), adapt the moment of electrical impulse to the circumstances of the watches use, correcting the position of the hands and offering the user a degree of precision equivalent to or better than 10 seconds per year.


An indefinite medium in which life with all its changes goes on irreversibly, and events and phenomena occur.


French for "whirlwind". The balance, pallet, and escape wheel are mounted in a rotating carriage which generally makes one rotation per minute. The purpose of the "tourbillon" is to average the errors in the vertical positions. Patented by Breguet on June 26, 1801.


The length of time between two consecutive passages of the sun through the meridian at any given place.


Very high frequency sound waves, over 18,000 vibrations per second, traveling through a liquid in which parts are immersed for thorough cleaning.


Motion of balance from one position of maximum displacement to the next. (1/2 Oscillation)