Jaeger-LeCoultre Caliber 916 – Overview from Technical Document 1160_JLC (Pages 1–2)
The Jaeger-LeCoultre Caliber 916 is a historically significant automatic movement, best known for powering Memovox models—specifically the automatic alarm watches produced in the late 1960s and 1970s. Pages 1–2 of technical document 1160_JLC introduce this caliber’s general architecture and essential specifications, serving as a reference for watchmakers beginning disassembly or familiarization.
Type: Automatic, manual-wind capable
Functions: Hours, minutes, central seconds, alarm (on/off, set via central disc)
Jewels: 22
Frequency: 28,800 vibrations per hour (4 Hz)
Power Reserve:
Timekeeping barrel: ~45 hours
Alarm barrel: ~20 hours
Diameter: ~30.2 mm
Height: ~7.6 mm (due to alarm mechanism)
The Caliber 916 was revolutionary for its time as the first automatic alarm movement to use a high-beat rate (28,800 vph) and an oscillating weight mounted on a ball bearing—a feature that improved durability and winding efficiency.
Page 1 outlines the overall movement layout, introducing the core elements:
Twin-barrel system: One for timekeeping, one for the alarm
Rotor system: Full-rotor bidirectional winding, with separate winding paths for the two barrels
Crown functionality:
First crown position sets the time
Second crown winds and sets the alarm via the rotating inner disc on the dial
Page 2 includes early schematic diagrams identifying:
The automatic winding bridge
Alarm hammer and trigger lever layout
Gear train positioning, including escape wheel and center seconds pinion
Basic part codes (used in later pages for exploded views)
Silent automatic winding system: The rotor winds the main barrel efficiently without significant noise
Alarm mechanism isolation: The alarm operates independently, avoiding interference with timekeeping
High-beat precision: Caliber 916 was among the first alarm watches to use a 28,800 vph balance for enhanced rate stability
Pages 1–2 of document 1160_JLC serve as an introductory guide to Caliber 916, offering essential specifications and a general movement diagram. This section is crucial for any technician preparing for detailed work, as it introduces the dual-barrel system, rotor layout, and the unique coupling between automatic winding and alarm functionality. Subsequent pages would go on to detail part-by-part diagrams and servicing instructions. As introduced here, the 916 is a landmark JLC movement—technically ambitious, beautifully engineered, and highly collectible.
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