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Seiko 11A
Manual · 5.75‴ x 6.75‴ · Japan · 1965
Dimensions
12.97 mm x 15.23 mm
Height
3.50mm
Jewels
21
Power reserve
—
Timegrapher
Beat rate
21,600bph
Frequency
3Hz
Reference: healthy amplitude ≈ 270–315° fully wound (>200° at 24 h); beat error ideally < 0.5 ms.
Movement
| Movement type |
Manual
Purely mechanical movements wound by hand via the crown, which tensions the mainspring to store energy. As the spring unwinds, it drives the gear train at a controlled rate set by the escapement and balance. Typical power reserves range from 38 to 80 hours, requiring daily or near-daily winding to keep the watch running.
|
|---|---|
| Winding type |
Stem Winding (Crown)
Winding the mainspring by turning the crown attached to the stem, transmitting torque through the winding pinion. Patented by Adrien Philippe in 1842, it replaced key winding and remains the standard manual winding method for both pocket watches and wristwatches.
|
| Setting type |
Stem Set (Crown Pull)
The dominant modern system: pulling the crown out to a setting position engages the hand-setting mechanism. Introduced in the late 19th century and refined into multi-position crowns (date, time, GMT). Used in virtually all modern wristwatches and most 20th-century pocket watches.
|
| Escapement type |
Swiss Lever
The undisputed standard of modern mechanical watchmaking. Through an elegant interplay between escape wheel, pallet fork, and balance, it delivers reliable impulses with the safety of 'draw' to keep the lever locked. Refined since the 18th century, it powers almost every quality mechanical wristwatch made today.
|
| Control type |
Balance Wheel
The heart of mechanical timepieces, the balance wheel is an oscillating component that, together with the hairspring, forms a harmonic oscillator regulating the gear train's pace. Its steady back-and-forth motion ensures the even release of energy from the mainspring, governing the watch's accuracy.
|
| Regulator type |
Pinned Regulator (or Index Regulator)
The most traditional regulator, consisting of a movable index pointer fitted with two curb pins (or a pin and a boot) that embrace the hairspring. Sliding the index along its scale changes the spring's active length, adjusting the rate. Simple, reliable, and easy to service, it remains the workhorse standard across countless mechanical movements.
|
| Shock protection |
Diashock
Seiko's in-house shock protection system, introduced in 1956 and refined ever since. Functionally similar to Incabloc but with proprietary geometry tailored to Seiko calibres, from entry-level 7Sxx automatics to high-end Grand Seiko movements. A cornerstone of Seiko's reputation for mechanical durability.
|
Specifications
| Lignes | 5.75‴ x 6.75‴ |
|---|---|
| Shape |
Barrel (Tonneau)
Known for its barrel-like shape, it's elegant and often associated with luxury watches.
|
| Hand count | 3 |
| Further measures | Mounting Diameter (Dm): 13.0 x 15.15mm |
Origin & References
| Manufacturer | Seiko |
|---|---|
| Country | Japan |
| Launch year | 1965 |
| COSC certified | No |
| Signature | ca. 1965: Seiko, Japan, 17J.; Diashock |
Notes
Other data: balance staff:
Seiko 315110
stem:
Seiko 351110 / 351111
short / long
mainspring / battery:
Seiko 205111
Ranfft mentioned about this caliber: There are variants with this quantity of jewels 17, 21
Ranfft mentioned about this caliber: There are variants with this quantity of jewels 17, 21
Compatible Parts
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