Lorologiese.com – Chronoservice.ch Sagl © 2025 All Rights Reserved
Made With ♥ In Aldeia
The Birth of Patek Philippe’s First Indirect Seconds Movement: The Evolution of Caliber 12-120 SC – Part 1
The Crisis of 1929 and the Stern Takeover
The financial collapse of 1929 had severe consequences for the Swiss watch industry, and Patek Philippe was no exception. The economic downturn led to a decline in luxury watch sales, placing the company in financial distress.
As a result, Patek Philippe was put on the market in search of a buyer who could ensure its survival. The firm was initially offered to the Jaeger-LeCoultre, a key supplier of movements to Patek Philippe at the time. However, despite their long-standing partnership, Jaeger-LeCoultre declined the offer.
The search continued, and the opportunity was presented to Charles and Jean Stern, owners of Fabrique de Cadrans Stern Frères, a company specializing in high-quality watch dials.
The Stern family had already established a strong relationship with Patek Philippe as their primary supplier of dials, making them a logical candidate for acquisition.
Unlike Jaeger-LeCoultre, the Sterns saw immense potential in Patek Philippe and decided to take control of the brand, ensuring its continuation as an independent watchmaking powerhouse.
In 1932, the acquisition was finalized, marking the beginning of a new era for Patek Philippe. Under the Stern family’s leadership, the company embarked on a strategic transformation, emphasizing technical innovation and in-house production. This shift laid the foundation for the development of Patek Philippe’s first fully in-house movement, the Caliber 12-120.
The First Patek Philippe Watch Under Stern Ownership: Ref. 96
Following the Stern family’s acquisition, Patek Philippe introduced its first new watch model, the Reference 96, in 1932. Designed with Bauhaus principles in mind, the Ref. 96 featured a minimalist, highly legible dial and a sleek, proportionate case that set a new standard for dress watches.
The design was credited to David Penney, whose emphasis on functional elegance helped define the aesthetic of Patek Philippe for decades. However, due to the transition period following the takeover, the first two years of production relied on existing Jaeger-LeCoultre movements, as Patek Philippe had yet to complete the development of its own in-house calibers.
This practical approach ensured the seamless introduction of the Ref. 96 while the company worked towards its long-term goal of full movement independence. In 1933 Patek Philippe appointed Jean Pfister, formerly the head of Tavannes Watch Co. in Geneva, as the company’s technical director.
Recognizing the importance of manufacturing independence, Pfister was committed to developing in-house movements. Under his leadership, the company introduced its first proprietary wristwatch movement, the Caliber 12”’120, in 1934. The Caliber 12”’120 was designed with a traditional Genevan architecture, reflecting the brand’s heritage. It featured a subsidiary seconds, positioning the fourth wheel at six o’clock to drive the seconds hand directly.
This layout optimized the movement’s volume by arranging components on a single plane. The movement’s construction included individual bridges for the escape wheel and fourth wheel, while an elongated bridge spanned the second and third wheels.
This separate-bridge design, prevalent in early 20th-century hand-wound movements, facilitated easier servicing and provided ample surfaces for decorative finishing, such as anglage and sharp inward angles, resulting in very good looking movements.
Notable details of the Caliber 12”’120 included a balance with screws for inertia adjustment. The balance cock featured a wide circular hub, secured by two screws to retain the cap jewel, offering a large surface for black polishing—a traditional design element often found in pocket watches prior to the adoption of shock absorbers. Black polishing, also known as “specular polishing” or “poli noir”, is a meticulous finishing technique used in high-end watchmaking to create a perfectly smooth and reflective surface that appears jet black under direct light due to the way it reflects at certain angles.
Achieved by polishing steel or brass components with fine abrasives on a tin or zinc plate using diamond paste, this process requires extreme precision to ensure a flawless, distortion-free finish. Black polishing is also functional, as it reduces corrosion and provides a perfectly flat bearing surface that enhances component longevity and performance.
This manually wound movement measures 12-ligne (27mm) diameter and was designed with a subsidiary seconds function, positioning the fourth wheel at six o’clock to drive the seconds hand directly. The seconds hand plays a crucial role in mechanical timepieces as it visually indicates the continuous passage of time and confirms the movement’s operation.
In traditional mechanical watches, the natural placement of the seconds hand is off-center, positioned directly on the fourth wheel, usually at the six o`clock position where the wheel does one turn every 60 seconds. To achieve a central seconds display, the gear train must be modified, making it a more complex mechanism and an added complication in movement design.
In 1939, Patek Philippe sought to introduce a central seconds feature, leading to the development of the Caliber 12”’120SC (Seconde Centrale). They talked to their long time complication partner, Victorin Piguet & Co., a company which played a crucial role in Patek Philippe’s early development of complicated movements, particularly in the realm of chronographs.
Founded in the Vallée de Joux, the firm was renowned for its expertise in manufacturing highly sophisticated ébauches for prestigious watchmakers. Throughout the late 19th and early 20th centuries, Victorin Piguet supplied Patek Philippe with some of its most intricate calibers, including split-seconds chronographs and perpetual calendars.
Their collaboration resulted in groundbreaking timepieces, such as the early single-button chronographs of the 1920s, which laid the foundation for Patek Philippe’s later dominance in high-complication watchmaking.
Collaborating with Victorin Piguet, they incorporated an indirect center seconds mechanism on top of the existing 12”’120 movement. The Caliber 12-120SC represents an exceptionally sophisticated technical solution for achieving a central seconds display.
One of the fundamental challenges was that the original 12-120 did not have the space to accommodate a center seconds function.
Rather than enlarging the movement or disrupting its established architecture, Patek Philippe and Victorin Piguet devised an indirect central seconds mechanism, incorporating a complex system of intermediate wheels to transfer power from the fourth wheel at six o’clock to the center.
This solution, though intricate and costly to manufacture, preserved the movement’s compact form. The additional wheels were positioned above the going train; this mechanism comprised three additional gears driven off the fourth wheel at six o’clock, relocating the seconds indication to the center. A pivoted lever supported an intermediate wheel, and a tension spring applied pressure to maintain engagement between the wheels, reducing the tendency for the seconds hand to flutter due to backlash.
1. small seconds wheel
2. pivoted lever
3. tension spring
4. transmission – middle – wheel
5. center seconds wheel
6. stop screws
Beyond its technical ingenuity, this configuration also elevated the visual appeal of the movement, with its multi-bridge layout providing more surfaces for anglage, sharp bevels, and Geneva stripes, hallmarks of high-end watchmaking.
While later calibers adopted direct-drive solutions for efficiency, the 12-120SC remains a testament to Patek Philippe’s commitment to innovation, craftsmanship, and the pursuit of mechanical perfection despite inherent design constraints.
This mechanism comprised three additional gears driven off the fourth wheel at six o’clock, relocating the seconds indication to the center. A pivoted lever supported an intermediate wheel, and a tension spring applied pressure to maintain engagement between the wheels, reducing the tendency for the seconds hand to flutter due to backlash.
By 1949, Patek Philippe introduced the Caliber 27SC, featuring a directly driven central seconds.
We will look into this topic next week.
