JLC 631

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Calibre 631 was a quartz watch movement with a mechanical chronograph developed by Jaeger-LeCoultre and also used by IWC.

Introduced in 1987, Calibre 631 was the second member in the Jaeger-LeCoultre Mechaquartz family after Calibre 630. It was a complicated movement, with 25 jewels and 233 components.

There are two motors in the calibre:

  • One powers the main timekeeping hands at a frequency of 1 Hz
  • A second powers the mechanical chronograph at 4 Hz

Since the chronograph is mechanical, it has the same feel as a conventional chronograph movement, including mechanical zero reset. Yet the Mechaquartz was much more compact than a conventional automatic chronograph movement.

Note: There is conflicting information on the quartz frequency, with some sources claiming dual 1 KHz and 4 KHz crystals and others claiming 32 KHz.


Calibre 631 was widely used in chronograph watches in the 1980's and 1990's.

External Links




Quartz movement with mechanical chronograph


Hour, minute hands
Small seconds at 6:00
Chronograph with 30 minute and 12 hour subdials at 9:00 and 3:00, respectively


H 3.8 mm
D 23.3 mm
25 jewels
233 components
Frequency 32 KHz

Production period: