Wostok 2809

 
Wostok 2809

Wostok 2809

Description

The probably most interesting und highest quality wristwatch movement of russian production was then 12 1/2 ligne caliber Wostok 2809, also known as caliber “Wolna”.

It takes many inspirations from the Zenith 135, which is considered as one of the best every build chronometer movements, like the large balance wheel, the fine regulation disc and the lack of a center minute wheel.

base plate

base plate

Of course, all important bearings use rubies, only the mainspring barrel and the second wheel, which turn slowly and with enough force, use metal bearings.

base plate with escape wheel cock

base plate with escape wheel cock

The escape wheel bearing is special for this movement, as it is located under an own, very flat cock with a cap jewel. On the dial side, there’s a cap wheel, too, for better oil keeping and as a protection against dirt.

gear train

gear train

The gear train of the Wostok 2809 is unusually constructed and was probably inspired by the Zenith 135:

The mainspring barrel drives the second wheel, followed by a double third wheel, fourth wheel and escape wheel.

The center seconds pinion is driven indirectly by the double third wheel, while only the uppar third wheel engages with the pinion. This construction ensures flatter-free driving of the central seconds hand without a need for a friction spring.

Mainspring barrel, great driving wheel and center seconds wheel are both beared under the barrel bridge, while third and fourth wheel have their own bridge, and have got a cap jewel each on the dial side.

side view of the gear train

side view of the gear train

The escape wheel is so flat, that the very large Glucydur screw balance revolves over it.

Interestingly, all screws on the balance wheel have got the same distance, so that it looks, like their function is mostly aesthetical, than to perfectly balance it.

The Wostok 2809 runs slowly with 18000 A/h and the uses two russian inhouse shock protections.

The hairspring has got an Breguet end curve and its effective length is adjusted with a long regulator arm, which is fine-tuned on a curved disc. Theoretically, the tuning should achive a deviation of maximal -10 to +5 seconds per day, but practically, hardly any specimen reach these values, they all tend to run significantly slower.

empty dial side

empty dial side

On the dial side, the hands are driven by the second wheel, which engages with the spring-beared exchange wheel. This spring reduced fluttering of the hands.

dial side with cannon pinion

dial side with cannon pinion

The cannon pinion is very broad.

Wostok 2809: Dial side

Wostok 2809: Dial side

The hour wheel has got an unusual high amount of teeth. I cannot remember having seen this on any other movement.

Conclusion

The Wostok 2089 (Wolna) is a really impressive movement and shows, what achievements the russian watch industry was capable of, and even it it shows rather poor timing results after 60 years, its construction is so special and unique, that it definitly ensures for enthusiasm.

In the lab

It got a simple service, but the balance wheel bearings could not be cleaned, because of non-available spare parts and the too large risk to damage the otherweise well working movement.

Timegrapher result

The timegrapher results are pretty far of what you expect from a “precision” movement.
Like almost all 2809 calibers, the specimen shown here also runs too slow, even in “fastest” position of the regulator arm.
The large beat error numbers, which cannot be corrected, and the high deviation rates over all positions show, that this movement has pretty much reached its end of life, or it happend, what was expected above, that the balance wheel screws only have an aesthetically effect, but were not used to balance the wheel.

horizontal positions
dial up -27 s/d 255° 9.2ms
dial down -35 s/d 295° 7.8ms
vertical positions
crown right (12 up) +13 s/d 199° 9.9ms
crown up (3 up) -31 s/d 206° 9.9ms
crown left (6 up) -50 s/d 208° 9.9ms
crown down (9 up) -25 s/d 190° 9.9ms

Technical data

Manufacturer:Wostok
Caliber:2809
Size:12 1/2''' (measured: 28,0mm)
Height:4,85mm
A/h:18000
Number of jewels:22
Escapement:Pallet lever
Balance types: Glucydur screw balance
Shock protection(s): Poljot
Balance bearing / direction hairspring:Clockwise
Moveable stud:no
Adjust mechanism:Cam
Construction:
  • lever
  • escape wheel
  • seconds wheel, third wheel, center second pinion
  • large driving wheel, mainspring barrel
Construction type:solid construction
Winding mechanism:yoke winding system
Setting lever spring:5 hole(s)
Features:
  • SCI (indirect center seconds)
Literature: Flume: K2 - / K3 56
Inventory number:20055

Usage gallery

Wostok Precision gents watch

Wostok Precision gents watch

Links

This movement is a kind donation from Rüdiger. Thank you very much for the great support of the movement archive!