JLC 631

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.

Applications

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

• Jaeger-LeCoultre Heraion Chronograph
• Jaeger-LeCoultre Kyros Chronograph
• Jaeger-LeCoultre Odysseus Chronograph
• Jaeger-LeCoultre Master Chronograph
• IWC Porsche Design Sportivo 02 Chronograph
• IWC Porsche Design Titan Chronograph
• IWC Ref. 3739
• IWC Ingenieur Chronograph
• IWC Portofino Chronograph
• IWC Ladies Portofino Chronograph
• IWC Flieger Chronograph
• IWC SL Chronograph
• IWC GST Chronograph
• Chopard Happy Sport Chronograph

External Links

• Mechaquartz Chronographs

Manufacturer: Jaeger-LeCoultre Description: Quartz movement with mechanical chronograph Functions: Hour, minute hands Small seconds at 6:00 Chronograph with 30 minute and 12 hour subdials at 9:00 and 3:00, respectively Data: H 3.8 mm D 23.3 mm 25 jewels 233 components Frequency 32 KHz Production period: 1987-