View single post by cnmark
 Posted: Mon Jul 23rd, 2007 02:38 pm
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cnmark



Joined: Mon Apr 2nd, 2007
Location: Hong Kong, Macau, Zhuhai
Posts: 115
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KenC wrote: Great pics and a good looking mov't.  Please tell me more about the movement, who makes it, where it is made, what quality control processes are in place, etc.
First the basic data of the ST19 movement:

Made by Tianjin Seagull Watch (Group) Ltd. Co. - in Chinese: 天津海鸥手表(集团)有限公司
(The worlds largest manufatcurer of mechanical watch movements)
Link to the movement division:
http://www.tjseagull.com/default.asp
(Chinese only, with a few English subtitles)

Movement production in:
Tianjin, Tianjin Municipality, P.R. China
Shenzhen, Guangdong Province, P.R. China

Column wheel chronograph movement

Data for the ST1901 variant:
2 register, small seconds at 9, 30 min counter at 3
Handwound
Diameter 31.3 mm

21600bph

Factory acceptance values:
Daily rate +30 to -10 sec/day
Power reserve 38 +/-2 hours

Actual observed values in "real life watches":
Accuracy +15 to +5 sec/day (fits into the statistical expected range) with some samples keeping exceptionally good time at +2 to +5
Power reserve 36 to 50(!) hours. The reason for this is that the mainspring basically can deliver a power reseve of 50+ hours, but to reach this a perfectly assembled and lubricated movement is necessary. In Chinese serial production this can not be guaranteed.

Seagull does not bother with offering "higher grade" movements receiving special treatment during assembly. Would they do so, these might certainly run at C.O.S.C. chronometer standards with the power reserve in the above mentioned range.

Short history:
The ST1901 movement is nearly identical to the Venus 175 - parts are interchangeable. But the movement is not a copy or clone. It actually is the Venus 175, because Seagull has purchased the tooling from Venus in the early 1960ies. Seagull did copy the tooling to be able to produce at 2 locations. Differences or improvements to the Venus 175 are the increased beat (the Venus only had 18000 bph) and an added incabloc style shock absorber.

A drawing (reduced size for posting):

Original size can be found here: http://www.tjseagull.com/wkt/1901.jpg

The movement comes in 6 variants:

ST1901
2 register,
small seconds at 9,
30 min counter at 3
(Ex Venus 175 - parts compatible, Venus parts can be used for repair)

ST1902
3 register,
small seconds at 9,
30 min counter at 3
12 h register at 6 (non chrono!),
The 12h register's hand is directly geared to the main hour hand - bloody useless. See the pictures of the "Schaferwatches" 3-register chrono, the 12h in the register is always in the same position as the main hour hand.

ST1903
3 register,
small seconds at 9,
30 min counter at 3
24 h register at 6 (non chrono again),
The 24h indicator is directly synchronized with main hour hand, either used as 24h indicator or with the hand replaced by a day/night disk as a faux moon phase - day night indicator.


New variants 2007

ST1905
2 register,
small seconds at 9,
30 min counter at 3
decentral power reserve at 4:30
(Plazeon chronos)

ST1907
2 register,
small seconds at 9,
30 min counter at 3
central power reserve indicator

ST1908
4 register,
small seconds at 9,
30 min counter at 3
date at 12
day/night window at 6

No info about the "missing" denominations ST1904 and ST 1906.

Seagull is developing or considering:
A true 3-register chrono with a 12h chronograph counter at 6, prototypes have been built, this might be one of the missing denominations.
A GMT variant of the ST1903, where the 24h register can be set independently - only in consideration.
The addon of an automatic winding mechanism to this movement (allegedly prototype status).

Last edited on Mon Jul 23rd, 2007 02:39 pm by cnmark