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As a follow-up to the last batch of reviews I have found a Seagull 1901 in need of a service, so I figured it would be a good time to take some pictures and discuss the movement.

Technical details: The Seagull 1901 is a 23 jewel, column wheel controlled, chronograph, lever movement operating at 21,600 bph. It has a running second dial at the 9 o'clock position, a 30 minute counter sub-dial at 3 o'clock, and a sweep second counter mounted centrally along with the timekeeping minute and hour hands. The chronograph functions are controlled through two buttons, one (at 2 o'clock) for starting and stopping the chronograph, one (at 4 o'clock) for resetting the second and minute counters. The column wheel prevents the action of the reset while the chronograph is running.

The 23 jewels are in the following locations:

Balance staff - 2 bearing, 2 cap, total 4
Impulse - 1
Pallet - 2
Pallet pivot - 2
Escape wheel pivots - 2
4th wheel pivots - 2
3rd wheel pivots - 2
Center wheel pivots - 2
Top Chronograph second counter pivot - 1
Top Chronograph minute counter pivot - 1
Slider Gear pivots - 2
Intermediate minute counter wheel pivots - 2

Here is the front, with the typical Chinese front plate. This does nothing but increases the thickness of the movement and retains the hour wheel (Something the Swiss prefer to do with the dial.)



And, the back



Some may not know what exactly a column wheel is, or how it works. So, here we have a close-up of the column wheel: (pardon the grease)

Chronograph engaged


Chronograph disengaged


As you can see, the column wheel is castellated, each function is controlled by an arm that has a nose that either fits in between the castellations, or is forced out from in between them. This keeps you from resetting while the chronograph is running, and such, and gives the column wheel chronograph its smooth action. You may also note that the noses are rather slight, but don’t worry that you will bend one, the action of the buttons does not bring direct force against these small delicate parts, the only force on these parts is their springs, even depressing the start/stop lever and the reset lever should hurt anything as there are no limiters on these, except when the button bottoms out in its well.

At the far left, is the start/stop lever, when the start button is pushed, the pawl moves out ward and rotates the column wheel clockwise one step. This will allow the nose of the slider gear carrier to drop in between two of the castellations and engaging the slider gear and the chrono-second wheel starting the chronograph (first figure). This will also block the hammer from falling (see the hammer nub at about 11:30 o’clock relative to the column wheel. Pushing the start button a second time (as in the second picture) will rotate the column wheel another step and the advancing castellation will force the slider gear carrier nose out disengaging the chronograph and freeing a space for the hammer nub to fall into. The hammer has its own sear triggered by the reset button not seen here.

Here are all the chronograph function parts. A comparison to the VAL 7734 and Poljot 3133, both cam operated chronographs, will reveal this has more parts (nearly 40% fewer on the cam action chronographs). From left to right: bottom row (screws not detailed): start/stop lever, start/stop spring, slider gear carrier spring, slider gear carrier and slider gear, hammer spring, hammer; second row: reset lever spring, reset lever, hammer sear, hammer sear spring, brake lever, intermediate minute wheel carrier and brake lever spring, intermediate minute wheel carrier and wheel, column wheel spring, column wheel; top row: chronograph bridge, minute counter wheel (below) chronograph second wheel.



Here is just the movement minus the chronograph parts



And the gear train



The balance with a nicely formed hairspring



Close-up of the pallet fork


The tension spring for the second hand



Layout of the basic time parts



The keyless works disassembled



Close-up of the escape wheel



A close-up of the balance cock and anti-shock setting





Anti-shock jewels



The movement is well made and runs extremely well, this one was timed to run, on average, 7 s/d. It runs very consistently. The chronograph functions are relatively light and crisp, unlike cam operated chronographs, which tend to be a bit stiff.

The Swiss have, in my opinion, missed a boat by ceasing the production of handwinding two resister chronographs and focusing exclusively on automatics. Most of the chronograph market (98% or more) use the 7750, 2894 or el Premero the 7750 (or a variant) mainly for the low to middle price range, the el Premiro for the higher price range and the 2894 the mid-range.

The workmanship on these movements is better than the run-of-the-mill Chinese ST16 and DG28, The gears are slightly thicker and the teeth, especially the fine teeth of the chronograph second wheel, are clean and well formed. The adjustments of the chronograph functions on this example (slider gear mesh on both sides, and intermediate minute wheel engagement) was adequate, but the second hand jumped slightly on engagement. Not all that bad, though.

Column wheel chronographs were abandoned by the Swiss, in general, due to the rather high surface finish requirement on the column wheel and the start/stop lever, mainly the claw that actually advances the column wheel. If these are not very well finished the column wheel will require more force to advance, giving the start/stop button a “sticky” action.

These movements are almost exact copies of the Venus 175, the chronograph parts, apart from the gearing of the chronograph second wheel, are exactly the same. Are these movements delicate, as several have asked? No. Not delicate, but these are much more sensitive to improper adjustment.

The major adjustment eccentrics of the Seagull 1901 (and Venus 175), (A) adjusts the engagement of the skider gear with the chronograph second wheel, (B) adjusts the engagement of the slider gear with the upper fourth wheel, (C) adjusts the engagement of the intermediate minute counter wheel and he trp finger on the chronograph second wheel and (D) adjusts the indexing of the minute counter wheel.



The major cause for concern, as far as I can see is in the casing. Improper casing, poor attention to dust elimination and just simply putting your thumb in the wrong place while installing a movement (be it Swiss, Russian or Chinese) will lead to problems. Precista uses the Seagull 1901 movement in the new version of the PRS-5, these are cased by Fricker, in Germany, and have a very low failure rate, which is on par with their Swiss movement watches. This tells me most problems seen in other watches are a result of the casing, not faults of the movement.

I like this movement, I hope to see Seagull come out with a date (at six) or an actual hour counter version in the future. Then someone can do a Benrus Skychief homage. Also, it might be possible to do true "fly-back" version, this would be nice.

The finish is not the movement’s strong point, this is my only gripe, and a relatively minor one. The Geneva stripes are rather coarse and uneven. These have been made with a fly-cutter, not grinding compound and a disk and the cross-feed was to high. The screws are chemically blued and almost baby blue in color, not the preferable blue-black of a good charcoal blue. There was to my surprise pearlage on the exposed portion of the mainplate around the balance, but it was so light I didn’t notice it until examining the mailplate under a loupe.



 

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Thanks for the tour Lysander :-!

Another one for the reference section |>
 

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Great review lysanderxiii, thanks again for all of your time and effort. This is a lot of good reading while I'm supposed to be doing something else. :-d

Technical details: The Seagull 1901 is a 23 jewel ...
I thought that Ivo (watchunique) established the ST1901 is a 21 jewel movement, hence the 21 Zuan on the dial of his 1963 re-issue? Hmmmm??

Thanks for the tour Lysander :-!

Another one for the reference section |>
Done!

Cheers,
gigfy
 

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Great review lysanderxiii, thanks again for all of your time and effort. This is a lot of good reading while I'm supposed to be doing something else. :-d



I thought that Ivo (watchunique) established the ST1901 is a 21 jewel movement, hence the 21 Zuan on the dial of his 1963 re-issue? Hmmmm??



Done!

Cheers,
gigfy
Unfortunately most of the sellers don't really know what the jewel counts are on the Chinese movements in watches they sell. Partly this has to do with the manufacturers playing games with customs tariff regs. Sea Gull used to print 7 jewels on the ST16 when it actually has 22 or more jewels :-d

Every time Lysander opens one up; we get a pleasant surprise :-!
 

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Unfortunately most of the sellers don't really know what the jewel counts are on the Chinese movements in watches they sell. Partly this has to do with the manufacturers playing games with customs tariff regs. Sea Gull used to print 7 jewels on the ST16 when it actually has 22 or more jewels :-d

Every time Lysander opens one up; we get a pleasant surprise :-!
But Ivo even had his watchmaker tear one down and count the jewels. :think:
 
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But Ivo even had his watchmaker tear one down and count the jewels. :think:
See...another surprise :-d

Remember the surprise I got when I opened this one up...



I'm not even going to tear this one down to count the jewels...it will probably only have 15 :roll:

So, the only sure way to know what is in a Chinese movement is to actually take it apart and count the jewels :)
 

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Mate

Absolutely fabulous.

One stupid question: I have a movement ST1901 that I bought direct in the raw - it has the little dial/cover - as you said to keep the wheels form falling off and the Swiss use the dial. Should I take this off when I am putting it in the case? or does if provide additional protection.?

What case - I have not decided, probably a Rodana - but will have to trial fit and get a movement ring plus other stuff. But that will have to wait. I will certainly post photos of it.

Dan
 

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Discussion Starter · #11 ·
Mate

Absolutely fabulous.

One stupid question: I have a movement ST1901 that I bought direct in the raw - it has the little dial/cover - as you said to keep the wheels form falling off and the Swiss use the dial. Should I take this off when I am putting it in the case? or does if provide additional protection.?

What case - I have not decided, probably a Rodana - but will have to trial fit and get a movement ring plus other stuff. But that will have to wait. I will certainly post photos of it.

Dan
If you look at the very first picture, you will see the hour wheel (the one visible wheel in the center) has a gear in the center that has no other gear meshing with it. This gear is for all the other complications that could be installed on the dial side of the 1901 to make the 12 hour sub-dial, moon phase, etc. Removing the cover plate will allow this gear to protrude above the rest of the main plate and foul the dial.

The cover plate has to be installed.
 

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Discussion Starter · #12 ·
Great review lysanderxiii, thanks again for all of your time and effort. This is a lot of good reading while I'm supposed to be doing something else. :-d

I thought that Ivo (watchunique) established the ST1901 is a 21 jewel movement, hence the 21 Zuan on the dial of his 1963 re-issue? Hmmmm??

Done!

Cheers,
gigfy
There are two hidden jewels, the lower jewel for the slider gear, and the lower jewel for the intermediate minute counter wheel. Unless the movement is disassembled, and these two parts flipped over and examined, you could miss these two in a jewel count.

If the manufacturer tells a seller it is a 21 jewel movement and the seller takes off the back and looks, he would conclude, it is, as two are not visible on an assembled movement.

Conversely, these two jewels could be replace by bronze bushings (at no real loss of performance, most Swiss manual chronograph had all bronze bushings in the chronograph section) in 21 jewel movements, these 21 jewel movements would look identical to the 23 jewel movement.

The original 19 jewel movements left out all four jewels in the slider gear and int. min. counter.
 

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Thank you for this wonderful post! :-!

I myself also wondered why there are so few hand-wound two register chrono's left. I think they are the best looking variations. Look at the old Landeron 248 chronos, or Pateks :p

Regards,

Martin
 

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Thanks for the answer to my question.

Again thanks for the post on the 1901 and all you others. It certainly has been a steep learning curve for me.

From no Chronos a month ago to now owning 1 Air Force re-issue and a new movement to 6 cases and on the hunt for more movements.

Truly insipirational
Dan
 

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Nice article. :-!
+1 and beautiful pics |> |> |>

I'm afraid I'll never have the patience to go through the exercise, but I bow down to the effort |>
 
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