Seiko 8R28

Calibre 8R28 is one of a family of column wheel chronograph movements from Seiko. Derived from the 6R family, this 8R family also includes the 8R39.

The 8R chronograph family was introduced in 2008 to power Seiko's Velatura 2-register chronographs. It is closely related to the 6R20, sharing that calibre's balance, winding, and works, and runs at the same 28,800 vph. The chronograph portion is a module added above the top plate. The 8R39 is identical in specification to the 8R28 but features a Spron 610 balance spring and 9S "Grand Seiko" escapement.

One unique feature of the chronograph is a three-pointed hammer, allowing all three chronograph hands to instantly reset together. This operates on three separate vertical clutches, as each chronograph hand is individually driven. The date also has an instant change mechanism.

Variants

Movement	Winding	Hands	Date	Subdial	Jewels	Power reserve
8R28, 8R39	Automatic	Hour, minute, chrono seconds	Date window	Small seconds, chrono hour, chrono minutes	34	45 hours

Applications

• 8R28
  • Ananta (SAEK, SRQ), Brightz Phoenix (SAGK, SDGZ), Sportura (SRQ)
• 8R39
  • Ananta (SAEK, SRQ)
• 8R48
  • Presage (SARK), Brightz (SDGZ)

External links

• BASEL-Seiko Valatura new automatic chronograph and more
• Clutch Performer
• Seiko 8R Family Reference

Description: Automatic movement Column-wheel Chronograph Functions: Hours, minutes, small seconds Automatic bidirectional winding Diashock Chrono function: central seconds, 30-minutes, 12-hours Vertical clutch Date wheel Data: 34 jewels 28,800 A/h Power reserve 45 hours Production period: 2008-present