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Chinese Watches Made in 1970s (1)

Article and photos by Youfang
March 2011

High Frequency Jewel Watch Made in Shanghai in 1973


1960s is an era when the world timepiece industry began to develop high frequency mechanical watch as technology of the balance spring regulator progressed. In 1966, the first high precision watch operating at 36000 vibrations per hour was produced by Girard-Perregaux in Swiss, exceeding the assumed technical limits for mechanical watches.

From 1970 onwards, China also started to work on high precision watches. According to the records collected so far, Shanghai Watch Plant, Shanghai Stopwatch Plant (later it was renamed Shanghai Diamond Watch Plant), Tianjin Watch Plant and Beijing Watch Factory were the major players, with Shanghai Watch Plant being the first pioneer in the field.

1, The Experiment of High Frequency Mechanical Watches Conducted by Shanghai Watch Plant

In 1973, Mr. He Shaozen and his Test Centre team at Shanghai Watch Plant made some changes with a few components in the inner works of Shanghai SS1A-K watch, a shockproof watch with beating rate of 21600 per hour. As the result they created a watch with 28800 beats per hour.


Inner work of the watch


All together they made 13 modifications with the components including barrel arbor, central shaft, the fourth wheel pinion, lever escapement, balance-wheel, mainspring and going train. The gear ratio between barrel and central shaft revised from 70:10 to 72:12, the ratio between the fourth wheel pinion and lever escapement increased from 84:7 to 112:7, and the diameter of the balance-wheel reduced from 10:3 to 8.6. The mainspring was treated with polytetrafluoroethylene (PTFE) to gain additional lubrication while an extra number of coils were added. The size of the wheel and the position of the holes on the main plate, barrel bar and intermediate plate were also adjusted accordingly.

During the trial production, 14 high precision mechanical watches were assembled in the first run, followed by 17 in the second term and 200 in the third stage. Of which, 100 were randomly selected for quality check by the Pilot Production Centre of Shanghai Watch Plant in March 1973, and found the average position error was within 15 seconds per day, with 68 per cent less than 10 seconds, while the daily error rate is limited to 10 seconds for 58 % of items. The trial production is declared a complete success.


Back of the watch


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