Surveying Seiko’s Half a century-plus of mechanical chronographs in this comprehensive historical feature from the Watchtime archives. Scroll down to discover the Japanese brand’s contribution to the world of chronograph wristwatches.
Caliber 5719: Japans first wrist chronograph
When Seiko set out to create Japan’s first wristwatch chronograph, its goal was to produce a watch that was as much a status symbol as a timing device. Suva Seikosha, meaning Seiko’s factory in the city of Suva, developed the watch, which was launched for the 1964 Summer Olympics. It is powered by the 12-line, hand-wound caliber 5719. Key features of this 6.1-mm-thick movement include a single button to trigger the chronograph functions, a horizontal coupling and a vertical wheel to control the start. Return-to-zero functions. The balance is paced at 5.5 hertz or 39,600 vph. With the chronograph mechanism switched on, the movement runs for 38 hours. The case is made of steel and measures 38.2 mm in diameter and 11.2 mm thick.
The watch lacks an elapsed-time counter, so Seiko equipped it with a rotating bezel calibrated in 1-minute increments. To measure periods longer than 1 minute, the user starts the chronograph and rotates the bezel until the tip of the large triangle is directly opposite the minute hand. After he stopped the chronograph at the end of the interval, he read the elapsed minutes using the rotating bezel and the seconds using the regular dial. The problem with this first chronograph series was that the bezel had a tendency to break. Seiko corrected this by replacing the fragile bezel with a solid, steel one.
Seiko brought another version of the movement, the 6.4-mm-thick Caliber 5718, into a limited-edition steel watch, which today is extremely rare and highly coveted by collectors. What looks like a date window at 12 o’clock is actually a golf-stroke or point counter, operated by two buttons on the left side of the case. Another unique feature is the subdial at 6 o’clock, which doubles as an elapsed-minutes counter and running-seconds display. On the edge of the dial is a tachymeter scale.
Caliber 6139: The first automatic chronograph on the market
It is well known that Swiss companies were working hard to develop the self-winding chronograph in the 1960s, but no one knows whether their Japanese competitors were aware of these efforts. Seiko began work on the self-winding calibers 6139 and 6138 in 1967, at a time when much of the watch industry was focused on quartz technology. It took the company just two years to develop the Caliber 6139. Very small, its diameter is 27.4 mm and height is 6.5 mm. Its mainspring was a ball-borne, center-mounted rotor that worked in conjunction with (and is still in use by) Seiko’s innovative Magic Lever, a click-winding system that harnesses the rotor’s kinetic energy in whichever direction the rotor turns. Once fully wound, the watch will run for 36 hours with the chronograph switched on.
To improve rate performance, the caliber developers gave the balance a frequency of 3 Hz (21,600 vph) instead of the then-standard 2.5 Hz (18,000 vph). Other technical features include a column wheel to control the functions of the column, a counter for 30 elapsed minutes at “6” and a vertical coupling. This last feature was quite innovative at the time: its debut here significantly preceded its premiere in Swiss watches. In addition to the date display, Seiko also equipped this model with a bilingual (Japanese and English) indicator for the day of the week.
5 A new movement housed in the watch, called the Speed-Timer, appeared in stores in mid-May 1969. Thus Seiko won the race to bring the first automatic chronograph to market. (Two competitors, Zenith and a consortium of other Swiss companies – Breitling, Heuer, Hamilton-Beuren and Dubois Depraz – brought automatic chronographs to market later in the year.) The 7.9-mm-thick caliber 6138, which debuted in 1970. The caliber differs from the 6139 because it has a running seconds hand and a counter for 12 elapsed hours. Seiko also incorporated the caliber 6138 into the so-called “Bullhead” model, similar to Omega’s manual-wind Bullhead, except that the pushers are on the top instead of on the side.
The equally slim Caliber 7018 was introduced in 1971: it had a 30-minute counter. Caliber 7015 and Seiko’s top-of-the-line Caliber 7016 followed in 1972. The latter has two concentrically rotating hands on the subdial at 6 o’clock: one for the running seconds and the other for counting up to 30 elapsed minutes.
Finally, in 2005, Seiko released the caliber 6S28 based on the 6S78. With this movement, Seiko made the same change that ETA did with its Caliber 7750, which changed to Caliber 7753 when its counter changed from “12” to “3” at 30 minutes. Caliber 6S28 has a date window between “4” and “5”.
Seiko sells the Caliber 6S78 to third parties as the “TC 78”. Among its customers were Junghans, which renamed the movement J890. TAG Heuer also acquired the TC 78, subjected it to major changes, manufactured most of the components in its own factory, and renamed it “Calibre 1887”.
Caliber Series 8R: Seiko’s Chronographs Today
In 2009, 40 years after the caliber 6139 premiered, visitors to the Seiko stand at Baselworld saw a brand new automatic chronograph called the Ananta. It has the caliber 8R28, which entered serial production in 2008. The newcomer combines traditional Seiko chronograph features such as a column wheel, vertical coupling, and magic lever winding system with more recent innovations to bring back all the chronograph counters, including the three-pointed hammer. Zero simultaneity. The 8R28 has a power reserve of over 45 hours. Seiko balance, balance spring and escapement. The movement is 28mm in diameter and 7.2mm thick. It has a frequency of 4 Hz (28,800 vph) and consists of 292 parts.
Launched in 2011, the caliber 8R39 is 7.6 mm thick. It is designed for dive watches. Caliber 8R48, 7.5 mm thick, followed in 2014 and is used in the Brytz, which is sold only in Japan.
As an alternative to ETA’s caliber 7753, third parties can opt for Seiko’s caliber NE88A. Based on caliber 8R39, it was launched in August 2014 and is 7.63 mm thick.
This article was originally posted in September 2017.