Landeron Caliber 4751 – A Rare Triple Calendar Chronograph with Moonphase

The Landeron Caliber 4751 is a manual-winding mechanical chronograph movement with full calendar and moonphase complications, developed by Charles Hahn & Cie (Landeron) during the post-war period (circa 1950s). It is one of the most technically complex and visually rich calibers ever produced by Landeron, standing apart from their mainstream cam-actuated chronograph family (like the Landeron 48).

Unlike the simplified and mass-produced cam-lever chronographs, the 4751 was built with an integrated triple-date chronograph system, designed for more refined, high-end applications. Watches using this movement are now highly collectible due to their rarity, mechanical depth, and vintage styling.

Technical Specifications

• Movement Type: Manual-winding mechanical chronograph

• Chronograph Mechanism: Column wheel (rare for Landeron), horizontal clutch

• Jewels: 17

• Frequency: 18,000 vibrations per hour (2.5 Hz)

• Power Reserve: Approx. 40 hours

• Diameter: Approx. 31 mm

• Height: Approx. 7.9 mm

• Functions:

  • Hours

  • Minutes

  • Small running seconds (at 9 o’clock)

  • 30-minute chronograph counter (at 3 o’clock)

  • Central chronograph seconds

  • Day and month windows (typically beneath 12 o’clock)

  • Pointer date (indicated by a central hand pointing to 1–31 scale)

  • Moonphase (usually at 6 o’clock)

Key Features

• Full Calendar: Displays day, date, and month using a combination of apertures and a pointer hand—commonly referred to as a triple calendar or complete calendar.

• Moonphase Display: Integrated within the 6 o’clock subdial, adding astronomical elegance.

• Chronograph Functionality: Includes both 30-minute totalizer and central chronograph seconds, with column wheel for smooth, precise operation.

• High Complexity: For its time and price point, this movement offered an unusually rich set of complications.

Watches Using Landeron 4751

Due to its complexity and cost, the 4751 was not widely used, and when it was, it appeared mostly in higher-end Swiss chronographs during the 1950s and early 1960s. Some of the known or attributed brands include:

• Croton Nivada Grenchen (notably the Chronomaster variants with calendar)

• Le Phare

• Wakmann

• Some Damas and Tradition-branded calendar chronographs

• Private-label Swiss watches targeting export markets

These watches typically featured 38 mm gold-plated or stainless steel cases, multi-scale dials, and beautifully domed crystals, reflecting the ornate design language of the time.

Servicing and Rarity

The Landeron 4751 is rare, both in production and in surviving examples. It is more complicated to service than cam-based chronographs due to the combination of:

• Column wheel chronograph control

• Multiple calendar mechanisms

• Delicate moonphase display

As such, repairs and restoration should be entrusted to experienced watchmakers specializing in vintage complications. Spare parts are extremely limited, making donor movements especially valuable.

Collectibility

The Landeron 4751 is highly collectible among vintage chronograph enthusiasts due to its:

• Mechanical richness

• Rare moonphase complication

• Triple calendar layout

• Elegant vintage aesthetics

When found in original condition, especially with clean dials and correct calendar discs, these watches can command significant attention in the collector market.

Conclusion

The Landeron Caliber 4751 is a hidden gem in the history of vintage Swiss watchmaking—a full calendar chronograph with moonphase from a manufacturer better known for mass-market movements. With its column wheel design and rare complication set, it represents a unique fusion of mechanical elegance and functionality, now treasured by collectors for its beauty, rarity, and horological significance.