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THE MINUTE REPEATER

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1. Definition and purpose of the complication

The minute repeater is an audible complication which, at the user’s request, strikes the complete time to the nearest minute. Unlike the Passing strike — which automatically stamps the hours and quarters over time —, the minute repeater is an on-demand strike: it sounds only when its mechanism is deliberately activated.

This audible signal is divided into three successive sequences: the full hours, the quarters of an hour elapsed since the last hour, then the remaining minutes since the last quarter. The minute repeater thus ranks among the Complications most complex in mechanical horology, and remains one of the most prized in haute horlogerie.

2. The release: slide (or bolt), striking barrel and “all-or-nothing” piece

The mechanism is activated by the pull-piece (or slide) — a sliding lever generally housed in the Flank of the Case middle. When the user activates the pull-piece, two actions occur simultaneously: on the one hand, the striking Barrel spring is wound; on the other hand, the counting components read the angular position of the Snail (cam)s (Cams), which encode the current Time.

An essential safety device completes this mechanism: the all-or-nothing piece. Its role is to prevent the striking mechanism from engaging if the pull-piece has not been pushed all the way to the end of its travel. Without it, a partial press — released prematurely — would cause the wrong hour to strike. The all-or-nothing piece only releases the striking Train (wheel train) once the pull-piece has reached its maximum position, guaranteeing a complete reading of the Time before the mechanism triggers.

In certain constructions, the pull-piece is replaced by a Pusher. A rarer version integrates the trigger directly into the Bezel, making the activation device invisible.

3. Reading the time: snails (cams) and racks (or pieces)

The counting of the number of strokes to be stamped is ensured by a set of stepped cams — the snails — and toothed sectors — the racks. Each snail is linked to a component of the Motion work:

— the hour snail, linked to the Hour wheel, has twelve steps corresponding to the twelve hours on the Dial;

— the quarter snail, linked to the Minute wheel or to an intermediate wheel, has four steps corresponding to the four quarter hours;

— the minute snail, with fourteen steps, encodes the fourteen minutes elapsed beyond the last quarter.

When the slide is actuated, the feeler of the hour rack rests on the hour Snail (cam): the height of the step on which it rests determines how many teeth the rack engages, that is to say how many strikes will be Stamping for the hours. The same principle applies to the feelers of the quarter and minute racks. All the information is captured mechanically before the striking begins, ensuring the consistency of the strike even if the mechanism is triggered at the precise instant of a minute change.

4. The striking sequence: hours, quarters and minutes

Once the count has been made, the striking Train (wheel train) unfolds in three distinct and successive phases.

The hours are struck first on the low-pitched gong, at a rate of one strike per elapsed hour (from one to twelve strikes).

Next come the quarter hours: each quarter is signalled by a double strike alternating high-pitched and low-pitched gongs, produced by the two hammers on the two respective gongs. This strike — commonly called the “ding-dong” — is the immediately recognisable sound signature of the repeater.

Finally, the remaining minutes beyond the last quarter are struck on the high-pitched gong, at a rate of one strike per minute (from zero to fourteen strikes). This difference in pitch between the phases allows the listener to decode the striking sequence without ambiguity.

5. Gongs and hammers

Sound production relies on two gongs — the term established by horological terminology to designate the resonant metal blades. A low-pitched gong and a high-pitched gong are tuned so as to produce a harmonious musical interval. These gongs are struck by hammers actuated by the strikingtrain.

In contemporary constructions, the gongs often take the form of metal wires coiled around the outer perimeter of the Movement. This architecture maximizes the length of the resonant wire and, consequently, the duration and intensity of the sound produced. The volume of the Case and the nature of its Material are decisive for the final acoustic quality.

The striking hammers must strike the gong with precise and regular force so that every stroke is identical in intensity and tone. Their Regulation / Adjustment in position and pressure is one of the delicate operations of Assembly and fine-tuning.

It is by a chime that is regular in rhythm and produces a pure, crystalline sound that a high-quality Minute repeater is distinguished.

6. Speed regulation: inertia wheel and Pallets (lever)-Regulator

Without a Regulating organ, the energy stored in the striking Barrel would be released in a fraction of a second, making the chime incomprehensible and irregular. Two types of regulators are used in Minute repeaters.

The flywheel (or governor) is a rotating organ whose blades, subjected to air resistance, slow the rotation of the striking train and impose a regular cadence. The flywheel’s blades move according to the energy received from the striking barrel under the effect of centrifugal force. At the start of the strike, when the barrel’s energy is greatest, the flywheel’s blades move away from the flywheel’s axis, further slowing the striking train. Conversely, when the barrel’s energy weakens, the flywheel’s blades move closer to the center and speed up the rotation of the striking train. Proper regulation of the flywheel ensures a constant rhythm of the struck blows throughout the striking process.

The regulating pallets (lever), consisting of a pallets (lever) with two pallets alternately engaging with a wheel, constitute the second system. An eccentric — a small offset cam controlling the position of the pallets — allows for fine adjustment of the striking speed after assembly, which facilitates fine-tuning and allows adaptation to the acoustic requirements of the case. In return, this system is slightly less silent than the flywheel and more sensitive to wearing positions.

7. Simplified repeaters

The minute repeater comes in several variants, depending on the division of time adopted.

So-called simplified repeaters exist with lower precision: the quarter repeater strikes the hours and quarters; the five-minute repeater strikes the hours and five-minute intervals; the half-quarter repeater, a historical rarity, strikes at intervals of seven minutes thirty seconds. These complications, more accessible to manufacture, involve fewer parts and less demanding implementation.

8. Relationship with passing strike and grande sonnerie

The minute repeater belongs to the family of strikes on demand and should not be confused with passing strikes, which automatically strike the hours or quarters without the user’s intervention.

Among passing strikes, a distinction is made between the grande sonnerie — which strikes the hours at every quarter and the Petite sonnerie, which strikes the hours only on the full hour, the quarters alone at the intermediate quarters. Both modes require a barrel dedicated to the passing strike, separate from that of the repeater. The minute repeater, for its part, strikes only on demand, to the exact minute.

In rare constructions, the same watch combines Minute repeater and passing strike (grande sonnerie or petite sonnerie), with independent testing of each. These pieces are among the most ambitious achievements of high mechanical horology.

9. Water resistance and its constraints

The water resistance of a minute repeater watch poses a difficulty inherent to the very principle of the slide (latch): any opening in the Case middle constitutes a weak point for protection against water. For a very long time, minute repeaters offered only protection against dust, without water resistance.

Technical solutions today make it possible to significantly improve this parameter. Specific gaskets around the pull-out piece or the pusher provide partial protection. It should be noted, however, that increased water resistance can alter the quality of the sound produced. This trade-off between protection and acoustic quality remains a permanent challenge for the designers of minute repeaters.

10. History and evolution

Originally, striking mechanisms were created to allow one to know the time during the night, at a time when no luminescent material was known.

Striking mechanisms are attested on pocket watches as early as the late 17th century. The English horologist Edward Barlow is generally credited with inventing a quarter-repeating mechanism for watches, around 1676. The minute repeater — more precise and more complex — appeared during the 18th century, and gradually spread within precision production.

The minute repeater represents the culmination of this evolution: it requires, within a reduced volume, a delicate manufacturing precision and adjustment that only the best horologists (watchmakers) mastered. Its transition to the wristwatch, in the 20th century, imposed an even more advanced miniaturization of all its components, particularly the snails (cams), racks and gongs.

Today, the minute repeater remains one of the most demanding complications to design and adjust. It is the symbol of fine mechanical watchmaking, combining artisanal know-how, acoustics and mechanical precision in the service of a sound signal of incomparable elegance.