A masterpiece of a thin automatic movement: the Longines Caliber L990, a late bloomer

In this installment of "The Legend of Masterpiece Movements," Masamasa Hirota, editor-in-chief of Chronos Japan, arbitrarily selects and explains some of the best timepieces. This time, we'll be looking at the Caliber L990, a thin automatic movement released by Longines in the 1970s. This movement is a masterpiece that combines excellent mass production with a highly rewound automatic mechanism.

Longines finally creates the decisive automatic watch

　Even Longines, a prestigious manufacturer, underwent repeated trial and error in developing an automatic movement. The challenges of incorporating a center second hand, making the watch thinner, and increasing its frequency, along with the need for cost reduction, made the development of an automatic movement even more difficult. Longines' automatic movement underwent frequent design changes because it lacked a definitive solution like Omega or Rolex. Indeed, the automatic movement Cal. 430 of 1967 took the world by storm with its high frequency of 36,000 vibrations per hour. However, in reality, this was an automatic movement made by the SA-Ebauches modified to Longines specifications, and the successor to the Cal. 430, the Cal. 432, was entirely made by the SA-Ebauches.

　A turning point came in the early 1970s. Ébauches SA and ASUAG acquired Longines' shares, stabilizing the company's financial situation. This prompted Longines to embark on the development of a new automatic movement, its first in ten years. The reason for this long absence was, according to Longines's documents, a "trauma to electric movements." Perhaps Longines saw its future in electromagnetic balance wheels rather than automatic movements, and the movement proved a huge commercial failure. The high-beat Caliber 430 and its successor, the Caliber 432, were merely alternatives to the electromagnetic balance wheel.

　Anyway, the Longines Caliber L890, completed in 75, was an automatic movement with a completely new design concept. It had a simple unidirectional winding mechanism and also featured a double barrel, one above the other. The document at the time of its release reads as follows:

"This 'E caliber' (the company's internal code at the time)... is characterised by two coaxial barrels with linked mainsprings, each rotating at a high speed of 17 revolutions per minute."

　The design concept of increasing torque per unit time by increasing barrel speed is now adopted by all manufacturers. Some movements made by Renaud & Papi (now Audemars Piguet Le Locle) (many of the movement designers from this workshop have adopted this design concept), automatic movements from Val Fleurier and Cartier, and Seiko's Cal. 9SA5 are all characterized by high-speed rotating barrels. The 75 Cal. L890 was a pioneer of this design concept.

　However, the Caliber L890, with its stacked barrels, was quite thick, measuring 5.2mm without a date and 5.75mm with a date. In response, Longines' designers began working on slimming down the Caliber L890 from 76 onwards, completing the Caliber L990 in 77. While the Caliber L890 was 27mm in diameter and 5.2 (5.75)mm thick, the Caliber L990 was 25.6mm in diameter and 2.95mm thick. Furthermore, this automatic movement had a simple design suitable for mass production.

　Longines was able to reduce the thickness of the movement by almost half by placing two barrels in parallel rather than stacking them. However, the concept of rotating a weak mainspring at high speed was exactly the same as the Caliber L890, and the mainspring torque was only 350g/mm2. After a long time without a decisive automatic movement, Longines finally released what could be called a masterpiece.

Lemania and Breguet

　However, the rise in the Swiss franc and gold prices, along with the popularity of Japanese-made quartz watches, drove automatic movements out of the market. Probably around the 90s, Longines sold the Caliber L990 to the ébauche manufacturer Nouvelle Lemania (now Breguet), who renamed it the Caliber Lemania 8810 and added it to their own lineup.

　The reason Lemania acquired the Caliber L990 was for its sister companies, Breguet and Ebel. The Caliber L990's thinness and low torque made it more suitable for high-end manufacturers than Longines. From the 90s onwards, Breguet and Ebel both adopted the Caliber 8810, successfully adding a modern automatic movement to their collections. It was after Lemania that the Caliber L990 really showed its true potential.

　Even now that Nouvelle Lemania has been absorbed into Breguet, this movement remains at the forefront. The Caliber 591 used by Breguet for some of its women's watches is the final version of the Caliber L990, which features a silicon balance spring and a free-sprung balance. While its power reserve of approximately 38 hours is too short by today's standards, its thinness and high winding efficiency, thanks to its weak mainspring, made it ideal for a women's automatic watch.

　The Caliber L990 was introduced so late that it became obsolete at Longines. However, its excellent design would later go on to support Breguet. Longines' last in-house movement was not an unfortunate masterpiece, but rather a late-blooming great talent.