Where mechanics meet mastery.
A column wheel is the notched wheel that coordinates the start, stop and return-to-zero functions of a chronograph. It sits between the pushers and the gear train and dictates, with millimeter precision, when the chronograph hands engage, disengage, and reset. The calibre is part of Aquastar's tool-watch heritage: a mechanism chosen for the job, not the price.
Most affordable chronographs use a cam, a flat lobed plate that performs the same job at lower cost and lower precision. The cam is made of two layers of metal cut into a profile; the column wheel is a single piece, with vertical posts arranged around a central pinion, and it usually requires high-precision machining to manufacture.
Why a column wheel feels different.
On a cam-actuated chronograph, the start pusher engages with a slight skip; you can feel the slack in the lever travel, and the chronograph seconds hand often jumps forward a fraction of a second before settling into its sweep. On a column-wheel chronograph, the engagement is crisp. The pusher meets a column, the column rotates one tooth, the clutch swings cleanly into mesh. No skip, no slack, no jolt. The chronograph seconds hand starts moving from the exact position where the start pusher was pressed.
This is what collectors mean when they describe a column-wheel chronograph as "having the right feel." The mechanism does what it shows.
How the column wheel actually works.
When the start pusher is pressed, a specific mechanical choreography unfolds inside the movement. The pusher stem meets a ratchet latch, which reaches over and pulls one tooth. In this action a ratchet latch hooks and turns the column wheel by exactly one indexed step. As the column wheel rotates, its raised columns and lowered gaps pass beneath a set of lever beaks, the shaped fingertips at the end of each control lever. A beak that had been sitting on top of a column now drops into a gap, or vice versa. That change of height is what actuates the chronograph.
Three levers are at work through the start-stop-reset cycle. The coupling clutch engages or disengages the chronograph seconds hand from the going train; a well-executed column wheel produces a smooth, counter-clockwise clutch that meshes without the fractional-second jump seen on cam mechanisms. The brake lever grips or releases the chronograph seconds pinion so the hand stops precisely where it stopped, not a hair beyond. The reset hammer flies against the heart-piece cams to snap the counters back to zero, and it does so only when the column wheel presents the right gap under its beak, never at any other position in the cycle.
Once the pusher is released, an elegant detent spring bounces back the pusher and holds the column wheel indexed between one of its eight positions. The resting positions of the lever beaks on the column wheel, that specific geometry tooth by tooth, are what define whether the chronograph is running, stopped or reset at any given moment. Nothing is sliding. Everything is dropped in and held.
This is why a column wheel is described as a coordinator rather than a switch. A cam performs the same three jobs with a single lobed plate; a column wheel performs them with a distributed system of levers, each dropping into its assigned gap at its assigned moment. The tactile precision of a column-wheel pusher press comes from this mechanical patience.
The calibre.
The 2020 Deepstar Chronograph runs an LJP (La Joux-Perret) mono-compax column-wheel movement, adjusted in five positions with certificate. The 2026 Deepstar III runs the manual-wind variant of the same architecture, hand-wound and built specifically for Aquastar, the closest mechanical equivalent to the original 1962 Valjoux 23. See it set against its peers in our guide to Swiss dive chronographs compared.
La Joux-Perret column-wheel chronograph, Soigné grade
High-end Swiss-made manufacture calibre, mono-compax column-wheel mechanical chronograph, top execution, adjusted in five positions with certificate.
| Specification | Value |
|---|---|
| Chronograph seconds | Centre |
| 30-minute counter | 3 o'clock |
| Running indicator (small seconds) | 9 o'clock |
| Dimensions | Ø 30,40 × 7,90 mm |
| Cage diameter | Ø 30,00 mm |
| Frequency | 4 Hz (28,800 vph) |
| Power reserve | 55 hours |
| Reassembly / winding | Bi-directional automatic (LJP G100); manual on Deepstar III |
| Jewels | 28 |
| Rotor & bridges | Aquastar-signed, decorated with Côtes de Genève and blued screws |
Where it sits today.
The column-wheel architecture is present in every modern Aquastar chronograph: the Deepstar 39 mm 2022 family (automatic), the Deepstar III Manual Wind (hand-wound), and the 60th-anniversary Airstar Re-Edition (the soigné-grade L113 variant). The three-hand Deepstar II and the Benthos line use simpler automatic calibres without column wheels, because they don't carry a chronograph.
Frequently asked questions.
What is a column wheel in a chronograph?
A column wheel is the notched wheel that coordinates the start, stop and reset functions of a chronograph. It sits between the pushers and the gear train, and its raised columns and lowered gaps determine when the coupling clutch engages, when the brake grips the seconds pinion, and when the reset hammer flies against the heart-piece cams. It is a coordinator rather than a switch, and it is the mark of a higher-grade chronograph movement.
How does a column wheel actually work?
When the pusher is pressed, a ratchet latch hooks and turns the column wheel by exactly one tooth. Lever beaks that were sitting on a column drop into the next gap, or vice versa, and that change of height actuates the coupling clutch, the brake lever, and the reset hammer. Once the pusher is released, an elegant detent spring bounces back the pusher and holds the column wheel indexed. Nothing slides; everything drops in and holds. The resting positions of the lever beaks on the column wheel are what define whether the chronograph is running, stopped or reset.
What is the difference between a column wheel and a cam?
A cam is a flat lobed plate cut into a profile that performs the same three control jobs (start, stop, reset) using a single component. A column wheel is a single-piece wheel with vertical posts arranged around a central pinion, and it distributes the same three jobs across separate levers. The cam is cheaper to manufacture; the column wheel gives a crisper pusher feel because the coupling clutch meshes cleanly without the fractional-second jump characteristic of cam-actuated chronographs.
Why does a column wheel chronograph feel different?
On a column-wheel chronograph, the pusher meets a column, the column rotates one tooth, the clutch swings cleanly into mesh. No skip, no slack, no jolt. The chronograph seconds hand starts moving from the exact position the pusher was pressed. On a cam chronograph the engagement typically shows a small skip as the lever travels through slack. That difference in pusher feel is what collectors mean when they call a column-wheel chronograph "having the right feel."
Does the Aquastar Deepstar use a column wheel?
Yes. Every modern Aquastar chronograph uses a column-wheel movement. The 2020 Deepstar Chronograph runs a La Joux-Perret LJP mono-compax column-wheel movement adjusted in five positions. The 2026 Deepstar III runs the manual-wind variant of the same architecture, hand-wound and built specifically for Aquastar. The 60th-anniversary Airstar Re-Edition runs the soigne-grade L113 variant. The three-hand Deepstar II and the Benthos line use simpler automatic calibres without column wheels because they do not carry a chronograph.
Where to go next.
See the Deepstar collection: every column-wheel chronograph we make today.
Read about the patented Deepstar bezel: the geometry above the calibre.
Read the eleven patents: the full archive, 1957 to 1977.
