Jaeger-LeCoultre Caliber 916 – Technical Overview from Document 1162_JLC (Pages 5–8)

Pages 5 through 8 of technical document 1162_JLC provide a detailed continuation of the service and construction guide for the Jaeger-LeCoultre Caliber 916, focusing on the calendar mechanism, the motion works, and precise lubrication and adjustment points. These sections are crucial for the full servicing of the Memovox automatic alarm movement, especially in date-equipped models.

Page 5 – Motion Works and Keyless Mechanism

This page outlines the manual time-setting and alarm-setting systems, including:

• Sliding pinion and clutch wheel

• Crown wheel, winding stem, and setting lever spring

• Hour and minute wheel configuration

• Alarm-setting disc drive

The diagram illustrates how the first crown position interacts with the motion works to adjust the time, while the second crown sets and winds the alarm.

⚙️ Watchmaker notes:

• Ensure smooth clutch engagement—stiff movement often indicates wear or misalignment of the clutch spring.

• When reinstalling the setting lever spring, be cautious of bending or breaking, as the part is delicate and essential for crown functionality.

• Keyless works should be lightly lubricated only at the contact points between the stem, clutch, and sliding pinion.

Page 6 – Calendar Mechanism (Cal. 916 with Date)

This page appears only in models equipped with a date complication, detailing:

• Date-driving wheel

• Date-jumper spring

• Semi-instantaneous date disc

• Hour wheel finger for calendar advancement

The date advances once per 24-hour cycle and is typically manually adjusted by advancing the hands.

⚙️ Watchmaker notes:

• The date jumper must have proper tension to ensure crisp advancement; weak springs can cause double-jumps or misalignment.

• Lubricate the jumper contact point only with thin oil. Grease or excess oil will cause sluggish performance.

• Always test the date function through a full 24-hour cycle before reassembly.

Page 7 – Lubrication Chart

This page provides a full lubrication map, showing the correct oil types and exact application points. Key components include:

• Escape wheel and pallet fork pivots (Moebius 9010 or equivalent)

• Rotor ball bearing (light grease or specific rotor oil)

• Barrel arbors and ratchet interfaces

• Date mechanism pivots and jumper spring

⚙️ Watchmaker notes:

• Do not lubricate the alarm hammer or its pivot—lubrication here reduces resonance.

• Avoid over-oiling the rotor bearing, as excess oil can leak and contaminate other components.

• Clean all reversing wheels thoroughly before oiling to prevent skipping in the winding system.

Page 8 – Fine Adjustment and Final Assembly

This page focuses on:

• Regulating the balance with the fine adjustment index

• Testing beat error and amplitude (target: <0>

• Installing the balance and testing escapement motion

• Checking alarm function in case context

⚙️ Watchmaker notes:

• Test the movement in multiple positions: dial up, dial down, crown down. The 28,800 vph escapement should offer stable amplitude across all.

• The alarm hammer should produce a clean strike sound. If it's dull, check for contact misalignment or case fitment issues.

• After complete reassembly, allow the movement to run for 12–24 hours and verify both power reserves (timekeeping and alarm barrels).

Conclusion

Pages 5 to 8 of document 1162_JLC offer the complete mechanical overview for servicing and regulating the Jaeger-LeCoultre Caliber 916, including both time and alarm systems, as well as optional calendar functionality. These pages emphasize careful handling, exact lubrication, and post-assembly testing, ensuring the movement delivers both accuracy and a crisp, reliable alarm chime. For any technician restoring a Memovox 916 model, these pages are indispensable for achieving full mechanical performance and preserving the iconic character of the movement.