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Seiko 436
Manual · 10.5‴ · Japan · 1974
Dimensions
23.69 mm
Height
3.85mm
Jewels
17
Power reserve
45h
Timegrapher
Beat rate
18,000bph
Frequency
2.5Hz
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 | 10.5‴ |
|---|---|
| Shape |
Round
It is the most common form that we can find.
|
| Complications |
Sweep Second
Contrary to the ticking motion of quartz watches, the sweep second hand in mechanical watches moves smoothly around the dial, offering a visual representation of time flowing continuously. This has become synonymous with the precision and craft of mechanical horology.
|
| Hand count | 3 |
| Hand sizes | 1.50 x 0.90 x 0.20mm |
| Further measures | Mounting Diameter (Dm): 23.6mm Stem height (T): 1.8mm All Incl.: 0.3mm Mounting Height (F): 1.2mm |
Origin & References
| Manufacturer | Seiko |
|---|---|
| Country | Japan |
| Launch year | 1974 |
| COSC certified | No |
| Signature | 1974: Seiko, Japan, 17 Jewels; Diashock
(Seiko 66B) |
Notes
Remarks: stem mechanism without setting-lever spring
Diafix combined settings for escapement wheel
differences not known between 66B, 436, 4361
Other data: balance staff: U3236 stem: W3181 mainspring / battery: Seiko 401660 balance staff ronda: 5206 (10,5) stem ronda: 1587 Mainspring: 1.350 x 9.000 x 0.110 x 380.000 mm
Diafix combined settings for escapement wheel
differences not known between 66B, 436, 4361
Other data: balance staff: U3236 stem: W3181 mainspring / battery: Seiko 401660 balance staff ronda: 5206 (10,5) stem ronda: 1587 Mainspring: 1.350 x 9.000 x 0.110 x 380.000 mm
Family
Series 66A - 6619B
66A: manual wind
6601A: automatic
modified hands gear:
66B, 436, 4361: manual wind
6601B: automatic
6602B: manual wind, date
6606B: automatic, day, date
6619B: automatic, day, date quickset
6601A: automatic
modified hands gear:
66B, 436, 4361: manual wind
6601B: automatic
6602B: manual wind, date
6606B: automatic, day, date
6619B: automatic, day, date quickset
Related calibers
Seiko 436
Seiko 4361
Seiko 6601A
Seiko 6601B
Seiko 6602B
Seiko 6606B
Seiko 6619A
Seiko 66A
Seiko 66B
Compatible Parts
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