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--- seiko_7s26 [02.12.2022 20:38] – created - external edit 127.0.0.1
+++ seiko_7s26 [03.12.2022 14:16] (current) – [Variants] gerdlothar
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+====== Seiko 7S26 ======
+{{wst>author|[[Foskett, Stephen|Stephen Foskett]] ([[https://grail-watch.com/|Grail Watch]])}}
+**7S26** is one of the most popular modern [[automatic]] watch movements from [[Seiko]]. Other closely-related members of this **7S** family include the **7S35**, **7S36**, and **7S55**, along with letter revisions of the 7S26.
+===== Overview =====
+The 7S26 family was introduced in [[1996]] as a mainstream automatic watch movement, replacing the [[Seiko 7002]] in many cases. Although earlier Seiko calibres featured [[quickset date]] using the crown in second position, the 7S26 adds a counter-clockwise quickset day feature as well. This family is non-[[hacking]] and not capable of [[hand winding]], unlike its follow-on movements like the [[Seiko 6R15|6R15]] and [[Seiko 4R35|4R35]].
+It is almost totally different from earlier [[Seiko 7002]] series calibres, though it does continue the "[[Magic lever]]" bi-directional winding design. Rather than using a dedicated winding bridge to locate the lever, the 7s26 family locates it with a brass bushing on one side and the rachet wheel on the other. The [[keyless works]] have been relocated from the top plate to the bottom plate, making it easier to service these components from the back plate rather than removing the entire works. The two added jewels, compared to its predecessor, support the [[third wheel]] and [[escape wheel]].
+===== Variants =====
+The **7S26A** was the original movement, introduced in 1996. It was revised with an [[Etachron]] regulator in [[2006]], becoming the **7S26B**. Another revision, the **7S26C** began appearing in [[2011]]. The **[[Seiko 6R15|6R15 family]]** was introduced in [[2006]] as a high-end derivative of the 7S26B, including the [[Etachron]] regulator and coming complete with a longer power reserve thanks to its [[Spron]] 510 mainspring. In [[2008]], Seiko introduced the **[[Seiko 4R15|4R15/4R16]]**, which were based on the 6R15 but lack the hacking and hand winding features. Finally, Seiko released the hacking/hand-winding **[[Seiko 4R35|4R3x series]]** which also lack the Spron 510 mainspring. These are sold as an upmarket alternative to the **7S26C**, also released in [[2011]].
+Like most Seiko movements, the 7S26 family operates at 21,600 vph. All models feature sweep hour, minute, and seconds hands. The 7S26 and 7S36 feature both day and date in a window, while the 7S25, 7S36 and 7S55 have only a date window. The 7S26 and 7S25 have 21 jewels while the 7S35, 7S36, and 7S55 have 23 jewels. The 7S55 is identical to the 7S35 except for a rotor decorated with [[Tokyo stripes]] for limited use in a line of [[Seiko 5 Superior]] watches from the late 1990's.
+The 7S26 movement family remains in production as of 2018, serving as the most affordable tier of automatic movements from Seiko. It is used in the SNK series of watches.
+^Movement ^Hands ^Date ^Subdial ^Jewels ^
+|7S26A, 7S26B |Hour, minute, seconds |Day and date |None |21 |
+|7S25A |:::|Date |:::|:::|
+|7S36A, 7S36B |:::|Day and date |:::|23 |
+|7S35A |:::|Date |:::|:::|
+|7S55A |:::|:::|:::|:::|
+{{wst>template_seiko_7s_family}}
+===== External links =====
+  * [[http://www.thepurists.com/watch/features/8ohms/7s26/|The Seiko Diver's 200 Meter SKX779 Featuring the 7S26 Automatic Movement]]
+  * [[http://quartzimodo.com/the-little-known-seiko-7s55-caliber/|The little known Seiko 7s55]]
+  * [[http://watcharama.com/the-seiko-4r36-family-in-brief/|Seiko 4R36 -The Family In Brief]]
+  * [[https://reference.grail-watch.com/family/seiko-7s/|Seiko 7S Family]]
+<WRAP ud ud_mov>
+**Description:**
+  * [[Automatic]] movement
+**Functions:**
+  * Hours, minutes, seconds
+  * [[Central seconds]]
+  * Rapid calendar advance
+  * [[Automatic]] [[bidirectional]] winding
+  * [[Diashock]]
+**Data:**
+  * Diameter 12 ligne (27 mm), H 4.9 mm
+  * 21 [[jewels]]
+  * 21,600 A/h
+  * Power reserve 40 hours
+**Production period:**
+  * Since [[1996]]
+</WRAP>
+{{tag>Movements Automatic_movements Magic_Lever_movements Seiko_calibres}}