Calibre record · Hand-wound chronograph

Valjoux 72

Documented

Valjoux's three-register column-wheel chronograph, supplied as an ébauche to Rolex for the early Daytona, to Heuer for the Carrera and Camaro, and to many other brands.

Manufacturer: ETA
Type: Hand-wound chronograph
Winding: Manual
Production: 1938–1974 (some sources date its introduction to 1946)
Country: Switzerland
Diameter: 29.5 mm (13 lignes)
Height: 6.95 mm
Jewels: 17
Frequency: 18,000 vph (2.5 Hz)
Power reserve: c. 48 h
Oscillator / escapement: Detached lever escapement
Complications: Column-wheel chronograph with 30-minute and 12-hour counters; small seconds

Figures are those commonly published for the standard version; individual versions and grades differ. “Undocumented here” means the value has not yet been confirmed for this record.

How it is built

A hand-wound, 13-ligne chronograph controlled by a nine-toothed column wheel — the castellated wheel that coordinates start, stop and reset — with a lateral (horizontal) clutch that brings the chronograph runner into mesh with the going train. The chronograph works lie on the back of the movement, which is why the calibre is admired through display backs and in auction photographs.

Its dial layout became the template for the three-register chronograph: running small seconds at 9 o'clock, a 30-minute counter at 3 and a 12-hour counter at 6, with chronograph seconds on the centre arbor. The balance beats at a leisurely 18,000 vibrations per hour.

The 72 was almost identical to the two-register Valjoux 23; the extra 12-hour train made it slightly thicker, at about 6.95 mm.

History

The 72 developed Valjoux's two-register chronograph calibres — the 14-ligne 22 of 1914 and the 13-ligne 23 — by adding a 12-hour counter at 6 o'clock, giving the classic three-register layout. It was made from 1938 until 1974, the year Valjoux's cam-switched automatic 7750 appeared. Brands bought it unfinished and adjusted, decorated and sometimes modified it themselves; Rolex's version was known as the 72B or Valjoux 722.

Watches fitted with it

Rolex Cosmograph Daytona, early references 6239, 6240 and 6241 (as the 72B/722)
Heuer Carrera and Camaro, e.g. Camaro ref. 7220
LeCoultre, Universal Genève and Gallet three-register chronographs

The numbers explained

18,000 vibrations per hour means the balance makes 5 beats (ticks) every second — 2.5 complete back-and-forth oscillations, or 2.5 Hz.
A sweeping seconds hand therefore advances in 5 small steps per second.
That is 432,000 beats a day. A watch that gains one second a day is out by about 1 part in 86,400 — roughly 11.6 parts per million.
Faster balances resist knocks and changes of position better but wear their pivots and need fresh oil sooner.

Convert beat rates and daily error with the Atlas tools · See a balance and escapement in the lab

How to recognise it

Three sub-dials — small seconds at 9, 30 minutes at 3, 12 hours at 6 — and two pushers on the right of the case.
On the back, an exposed column wheel and chronograph levers over a hand-wound movement with no rotor.
Valjoux markings and the calibre number on the plates, unless the watch brand has re-signed or refinished the movement (Rolex movements read 72B or 722).

For collectors

Because the same calibre sits in watches worth a few thousand and a few million, the case, dial and their originality decide the value. Ask for a photograph of the movement: check that the chronograph starts, stops and resets crisply, that the counters jump cleanly at each minute and hour, and that the movement number and finish match what the brand used at the time.

Versions and derivatives

Versions and derivatives of the Valjoux 72
Calibre	Difference
Valjoux 23	The two-register predecessor (30-minute counter only); otherwise almost identical.
Rolex 72B / Valjoux 722	Version made to Rolex's specification for the early Cosmograph Daytona and other Rolex chronographs.

Compared with related calibres

Specifications of the Valjoux 72 beside related calibres
Calibre	Type	Frequency	Jewels	Power reserve	Diameter	Production
Valjoux 72	Hand-wound chronograph	18,000 vph (2.5 Hz)	17	c. 48 h	29.5 mm (13 lignes)	1938–1974 (some sources date its introduction to 1946)
Valjoux 7750	Automatic chronograph	28,800 vph (4 Hz)	25	c. 42–48 h	30 mm (13¼ lignes)	1974–present
Omega calibre 321	Manual chronograph	18,000 vph (2.5 Hz)	17	c. 44 h	27 mm (12 lignes)	1946–1968; re-introduced 2019
Lemania 5100	Automatic chronograph	28,800 vph (4 Hz)	17	c. 45–48 h	31 mm (13¾ lignes)	1974–2002 (a 1998 Chronos article gives 1978 as the start)

Mechanisms in this calibre

Chronograph

Detached lever escapement

Related calibres

Valjoux 7750

Automatic chronograph · 1974–present

Omega calibre 321

Manual chronograph · 1946–1968; re-introduced 2019

Lemania 5100

Automatic chronograph · 1974–2002 (a 1998 Chronos article gives 1978 as the start)

Related records in the catalogue

Records whose titles name this calibre or a model family that used it. Earlier or later examples of a model may contain a different calibre, so check each record's description for the movement actually fitted.