How a Striking Watch (Minute Repeater) Works

The striking watch—and, more specifically, the minute repeater—is one of watchmaking’s most poetic, and most unforgiving, complications. Poetic, because it turns time into music. Unforgiving, because inside the case nothing is forgiven: not approximation, not a speck of dust, not lazy anglage. It’s an instrument, not a gadget. And when you ask how a striking watch works, the answer sits as much at the crossroads of precision mechanics as it does acoustics, metallurgy, and a very human obsession with making gears sing. Have fun spotting the hammers in the movement photos as you read the article.

What a striking mechanism is for (and why it was born)

Before electricity, you can’t read a dial in the dark. And the aristocracy of the 17th and 18th centuries had the insolent habit of wanting to know the time at night without waking the whole household—or lighting a candle above an inflammable wig. The first repeating watches were born from that: making the time “audible” on demand. You actuate a device, the watch counts out the hours, then possibly the quarters, then the minutes. Today, nobody needs a repeater. That is precisely why it fascinates: it exists because watchmaking likes to set itself mountains to climb.

Striking watch vs minute repeater: let’s talk terminology

In everyday language, everything gets lumped together. A clarification is in order.

The main families of striking mechanisms

• Repeater, the time is struck on demand (via a pusher or a sliding bolt).
• Passing strike, the time strikes automatically (petite sonnerie, grande sonnerie, etc.). That’s the case with the Christopher Ward C1 Bel Canto that I tested.
• Alarm, a different logic: you set it to trigger at a given moment.

The “repeater” levels

• Hour repeater, hours only.
• Quarter repeater, hours then quarters.
• Minute repeater, the classic Grail: hours, quarters, minutes.

In this article, we’re focusing on the minute repeater, the complication enthusiasts mention with a mix of reverence and a slight cold sweat.

How a minute repeater works: a symphony in several acts

Act 1: winding it up—the slide or the pusher

On many traditional repeaters, you’ll find a sliding bolt on the caseband. This isn’t an aesthetic whim; it’s a winding device. By sliding it, you tension a small dedicated spring, separate from the mainspring that powers the watch. The result is that the striking mechanism has its own energy reserve, independent of the going train. That’s a key point: you want the watch to remain a watch, even when it decides to play bell.

Some models use a pusher, or other architectures, but the principle is the same: you wind a striking spring.

Act 2: mechanically “reading” the time—the surprise of the snails

A minute repeater has to convert continuous information—the position of the hands—into a sequence of strikes. To do that, it uses snail-shaped cams, very literally called snails. There are generally three:

• hour snail, encoding 1 to 12.
• quarter snail, encoding 0 to 3.
• minute snail, encoding 0 to 14 (the minutes after the last quarter).

Racks (toothed levers) drop onto these snails and “read” their height. The higher the snail at the point where the rack lands, the more strikes will be sounded. This is a long way from digital. And yet it’s a form of mechanical computing: read, convert, execute.

Act 3: the brain—locking and sequencing

Once the information has been captured by the racks, a locking system prevents the parts from moving any which way. Because if you let a repeater improvise, it will improvise—just not in the way you’d like. Safety devices are essential: they prevent, for example, actuating the repeater while the mechanism is changing the display, or triggering two sequences at the same time.

This mechanical “brain” is a choreography of jumpers, rocking levers, clicks, and springs. In a well-designed high-grade repeater, everything is crisp, with no hesitation. In an average repeater, you sometimes hear a micro-waver, an unpleasant dead moment—like a pianist searching for the right key.

Act 4: the rhythmic engine—the regulator (or governor)

Here’s a detail many people overlook: a minute repeater must not only strike the gongs, it must strike them at the right tempo. Too fast and you can’t make anything out. Too slow and the sequence becomes a punishment. Everything depends on a striking regulator, sometimes called a governor.

Historically, you find anchor-type regulators, then centrifugal regulators, and today often very compact systems with pallets and inertia—visible as a small spinning fan during the strike. Its role is to absorb excess energy from the striking spring to impose a constant rate. A repeater without a regulator is a cascade of blows: indistinct and brutal.

Act 5: the voice—hammers and gongs

The most “visible” part is also the most misunderstood. When people talk about striking, they imagine bells. In reality, most minute repeaters use:

• two hammers, tiny polished steel mallets, spring-mounted,
• two gongs, thin hardened steel wires, coiled around the movement.

The hammers hit the gongs. The gongs vibrate. The case amplifies. And your wrist becomes the soundboard. Generally:

• the hours are struck on one gong (low tone),
• the quarters alternate the two gongs (low then high),
• the minutes are struck on the other gong (high tone).

Example: 10:23. The watch strikes 10 low notes, then 1 quarter sequence (low, high), then 8 high notes (because 23 minutes is 15 + 8).

Why it sounds “good” … or not: acoustics, materials, architecture

There’s a romantic idea that you only need to put gongs in a precious-metal case to get a heavenly chime. That’s false—or rather, incomplete.

The case, the first amplifier

The material and geometry of the case have a huge influence on the result. Rose gold, platinum, steel, titanium—each has its own signature. Platinum, for example, is dense, so it’s often more discreet, more muted, sometimes less powerful. Some manufacturers play precisely with that: a repeater in platinum isn’t made to “sound loud”; it’s made to sound true.

How the gongs are fixed

The gongs have an anchoring point, generally close to the movement, and their tension, length, curvature—everything is adjusted. It’s the work of both artisan and technician. Too tight and the sound turns dry. Not tight enough and it turns soft. And between the two is a narrow zone where the watch begins to “speak.”

Classic gongs vs “cathedral” gongs

You’ll sometimes hear the term cathedral gongs: they make more than one full turn around the movement. More length, therefore potentially more resonance, more sustain. Potentially. Because if the whole isn’t tuned, you mostly end up with more metal that sounds merely average.

Mechanical pitfalls: why it’s so difficult to make

A minute repeater combines three major problems:

• Miniaturisation, because everything has to fit within a wearable watch height.
• Energy, you need enough torque to strike without upsetting the movement.
• Parasitic noise, every friction point is a potential noise, every bit of play a hesitation.

Add to that the finishing requirements. Not to look pretty in photos, but because black polish, a clean bevel, a properly drawn surface also mean controlled friction—therefore a more consistent repeater. An acoustic complication is also judged by feel: the sensation of the slide, the crispness of the trigger, the smoothness of the mechanism.

Minute repeaters and safety: the invisible safeguards

Modern repeaters often incorporate safety features that prevent mechanical disasters. Among the most important:

• lockout during time-setting, to avoid striking on a display that’s “between” two positions,
• anti-return for the slide, so the winding remains stable until the strike is triggered,
• blocking if the spring isn’t sufficiently wound, to avoid an aborted strike—the watchmaking equivalent of a sentence left hanging.

In any case, remember this: the price of a minute repeater doesn’t just buy hours of assembly. It buys time spent listening, adjusting, listening again. A watch that can be “perfect on paper” yet mediocre to the ear is not rare. A repeater that sings is an encounter.

How to listen to a minute repeater (without playing conductor)

A few simple reflexes if you’re lucky enough to try one:

• Listen to the separation between hours, quarters, minutes. Everything should be legible.
• Listen to the decay of the sound: a beautiful sustain shouldn’t be messy.
• Listen to the mechanical noise: the regulator’s “hiss” is normal; parasitic clicking is less so.
• Try it several times: consistency is a sign of mastery.

And yes, you’ll want to trigger it ten times in a row. Everyone does. Even watchmakers. They just claim they’re “testing.”

A striking watch of the minute repeater type works like a small translation machine: it mechanically reads the time via snails, converts it into a sequence of strikes, regulates the tempo thanks to a governor, then sets gongs vibrating as they’re struck by hammers. After that, the case does the rest, like a musical instrument. It’s a complication where you can’t cheat: if it’s well designed, you can hear it. If it’s average, you can hear that too. And that may be the most honest reason to love it.