What is the difference between Sellita caliber SW200 and SW200-1?
In 2008, Sellita published a document about the evolution of the caliber SW200 automatic mechanism to the SW200-1.
According to watch movement manufacturer, the goal for the change is to:
Minimize wear and tear of the wheels in the automatic chain changing the tooth profile.
Which parts were changed?
The changes to the -1 variation include making modifications to the following components of the movement:
Axis of reduction wheel (1481)
Axis and wheel of ratchet wheel driving wheel (1482)
Ratchet wheel (415)
According to the documentation, other than the three components pictured above, all other parts of the caliber SW200 are interchangeable with the SW200-1. When performing maintenance or repair, these three components should be changed together to maintain functionality of the gear chain.
The gears on the original SW200 are following normal standards, however, Sellita found that each individual tooth has “slim geometry” and have been known to get damaged due to strong shocks to the watch. The new gear design provides power transmission equal to the SW200, but they strengthened the tooth geometry to reduce the risk of damage from strong shock.
The change of version is part of our ongoing improvement strategy to optimize the performance of our calibers. -Sellita
When did Sellita SW200 become SW200-1?
As mentioned above, Sellita began this change as far back as 2008. There is some confusion online about this date because the top of Sellita’s tech sheets say “R&D 08.04.13.” This was likely a revision date. The date of the actual document was 19.08.2008 (August 19, 2008). Sellita no longer provides tech sheets for the SW200, but the most recent one we found was from 2007. We also found an SW200-1 tech sheet from 2010. Therefore, it turns out that the SW200-1 is what most of the watch community is used to.