The SN2 is a 9 jewel, 18,000 bph manual wind watch movement manufactured by the Nanjing Watch Factory and first produced in 1968. The movement is noteworthy for being one of only three movements whose production was allowed by the Chinese Ministry of Light Industry to continue after the introduction of the Chinese standard movement (the others being the ST5 and SM1A). The SN2 has a drastically simplified design compared to other Chinese movements of the time, and Nanjing used it in their Zhongshan brand watches to offer an extremely low-cost option for the very poorest members of Chinese society, to whom even watches based on the standard movement were out of reach. Despite its cost-cutting design and construction, the SN2 has a reputation for acceptable time-keeping and boasts an impressive power reserve of over 50 hours.
The SN2 has a number of unique design features not seen in other Chinese movements, intended to reduce costs and facilitate easy maintenance:
- The wheel train bridge and winding bridge are a single plate
- The mainspring barrel is uncovered
- The keyless works uses a single part where standard designs use several parts
- The screws have extra-large heads and the different kinds of screw have visibly different shapes
Several factories manufactured watches with SN2 movements with higher jewel counts. It appears likely that they were upgraded from ebauches imported from Nanjing.
- Hengyang Watch Factory used 15-jewel SN2 movements in some Furong/Lotus brand watches.
- Jieyang Watch Factory used 11- and 17-jewel SN2 movements in some Kuihua brand watches and 17-jewel SN2 movements in some Bao Xuan brand watches.
- Zhengzhou Watch Factory used 9-, 16-, and 17-jewel SN2 movements in watches with a number of brand names, including Huanghe and Bawang.
Watch brands using the SN2
- Watchuseek forum thread: Restoring a Nanjing SN2 movement (many pics)