Universal Genève Caliber 138 – Ref. 1629: A Pioneering Automatic Movement with Swiss Precision

The Universal Genève Caliber 138, found in Reference 1629, is one of the most significant automatic movements in the brand’s history—and indeed in Swiss watchmaking as a whole. Introduced in the 1940s, it represents Universal Genève’s first generation of bumper automatic calibers, showcasing mechanical ingenuity during a time when self-winding technology was still in its formative years.

Caliber 138 is best known for its role in powering early automatic chronometers and elegant time-only models that combined convenience, performance, and understated luxury.

A Breakthrough in Self-Winding Technology

The Cal. 138 stands as a milestone in Universal Genève’s journey. At a time when automatic wristwatches were still relatively new to the market, Universal took a bold step with a bumper-style automatic winding system. Unlike today’s full-rotation rotors, this early design features a semi-circular weight that swings back and forth, hitting spring-loaded bumpers at each end of its arc.

This system was simple yet effective, and it allowed Universal Genève to produce thinner automatic movements compared to some competitors who used more complex or bulkier solutions. The Caliber 138 wound efficiently with normal wrist movement and became known for its durability and reliability.

Technical Specifications

• Caliber: 138

• Type: Automatic (bumper-wind)

• Jewels: 17

• Frequency: 18,000 vibrations per hour (vph)

• Power Reserve: Approximately 40 hours

• Functions: Hours, minutes, central seconds

The 138 was produced in several variations, including 138SS and 138C, with minor differences in bridge design, jewel count, and finishing. Most examples include Incabloc shock protection, a bi-directional winding bumper mechanism, and high-grade finishing with polished wheels and bridges.

One of its most unique features is the audible "thud" or "click" that can be felt and heard as the bumper rotor hits the spring stops—a signature trait of early automatics that many collectors find charming.

Ref. 1629 – A Watch Ahead of Its Time

The Universal Genève Reference 1629 was developed to showcase the Caliber 138. Designed as an elegant, mid-century dress watch, it features a streamlined case, clean dial design, and a classic three-hand layout with no date. Case sizes range from 33 to 35 mm, a standard for formal men’s watches of the era.

Cases were crafted from stainless steel, gold-plated brass, or solid gold, depending on the market and model year. Dials typically include applied hour markers, dauphine or leaf hands, and minimal text—often just “Universal Genève” and “Automatic.” Some rare models include “Chronomètre” markings, indicating higher-grade regulation.

The Ref. 1629 is known for its balanced proportions, gentle lugs, and understated elegance. The caseback is usually snap-on and may bear engravings or reference numbers, helping identify original examples.

Maintenance and Longevity

Despite its age, the Caliber 138 is surprisingly robust and serviceable. The bumper system is mechanically simple and can be easily cleaned and lubricated by a trained watchmaker. Parts availability remains fair, although rotors and springs specific to the bumper mechanism are less common and may need to be sourced from donor movements.

When properly maintained, Cal. 138 watches can offer reliable performance and excellent timekeeping, making them fully wearable decades after production.

Collector Appeal

Vintage enthusiasts highly regard the Caliber 138 for its historical importance, mechanical uniqueness, and vintage charm. Ref. 1629 watches with original dials, hands, and movements are becoming more difficult to find, and prices have steadily increased in recent years.

Collectors admire the combination of early automatic technology and classic Universal Genève design. The 138’s tactile feedback, audible bumper motion, and vintage proportions offer a uniquely satisfying wearing experience.

Final Thoughts

The Universal Genève Caliber 138, as seen in Reference 1629, captures a pivotal moment in watchmaking history—when brands began mastering the art of automatic movements. With its bumper-wind design, timeless styling, and mechanical reliability, it stands as a tribute to Universal Genève’s pioneering spirit. For collectors or enthusiasts seeking a vintage automatic with character and legacy, the Cal. 138 is a piece worth owning.