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Watch Words


The following pages are a glossary of terms associated with horology, watches and watchmaking. Please click on one of the links or glossary terms below to learn more about them. Most of the terms are enhanced with detailed imagery. If you would like us to list any other words that you think may be helpful, please contact me direct We will update the glossary frequently.


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Ratchet Wheel

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

The rachet wheel in the Unitas 6498 movement is clearly visible through the crystal backplate of the C8 Regulator.

Ratchet Wheel



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.




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

The C8 Regulator powered by a hand-wound Unitas 6498 has separate dials for hours, minutes and seconds, thereby ensuring greater accuracy.

C8 Regulator display




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.

Rotating Bezel




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.

An example of a detailed Côtes de Genève patterned rotor from the C9 Jumping Hour MK II.

C9 Jumpinng Hour MK2 Rotor


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