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Discussion Starter · #1 · (Edited)
Here's a pictorial break down of a Slava 2428 movement that I had in for service.

The 2428 is an interesting movement and has some fascinating design features that made it more interesting to work on than the normal run-of-the-mill movements.

A manual wind movement running at 21600bph it features 21 jewels, a day / date function with the date being quick set via a separate lever system activated by a small button on the side of the case.

The quick set date mechanism is mounted on a plastic movement ring separate from the movement main plate, see pictures below. The movement measures 31.8mm in diameter with the ring and 'nude' 24.9mm.
The main feature of this movement though is the use of two main spring barrels operating sequentially.

This is similar to the designs by Lange and Omega with the 8500, however those designs feature a sequential arrangement where one main barrel 'tops up' a secondary smaller barrel, the idea being to provide a longer and more consistent power reserve without the drawback of excessive power drop that affects a single long mainspring as it unwinds.

With the 2428 both mainsprings are of the same length so the reserve will be the same as if a single same length mainspring where used, however the power should be more consistent vs a single mainspring meaning more consistent rate over time. Using two smaller mainsprings doesn't save space though as additional intermediate winding gears and a power transfer gear need to be accommodated.

The wheel train layout is similar to the ETA 24xx in that the cannon pinion is of a similar design and the movement features a displaced center wheel. However, on the ETA the cannon wheel/pinion is driven by the third wheel here it's driven from the 4th wheel which also drives an intermediate center seconds wheel so there are 5 wheels in total. The ETA combines the 4th wheel and center seconds into a single part.

Movement, I could not find any markings on it at all.



The dial is a push fit on to the movement with the feet set into the plastic. Care is needed in easing it off as it is a tight fit. The Blue arrow shows the quick set lever.





The date wheel is a snap fit over the hour wheel and care is needed in removal. Pulling against the thin brass wheel will separate it from its pinion. Use the cutouts and lift the pinion wheel not the disk.



We can now see the dial side and the quick set date lever (red arrow) and the date advance lever on the movement (blue arrow)



A close up:



Date plate removed:



With the date wheel removed we can see how the quick set levers interact with the set lever on the movement. The levers are pinned to the movement ring with plastic studs and don't seem to be removable.



Luckily there is enough room to push the movement up opposite the date lever and slide it from the movement.



Dial side, note the ETA like cannon wheel and pinion







The motion works side, note the twin barrel wheels, single click and crown wheel. The barrels run sequentially but are wound in parallel.







With the bridges removed we can see the motion works and the flow of power to the Escape wheel. Note the indirect center seconds has been removed. 1 is the displaced center wheel, 2 is the third wheel and 3 is the 4th wheel. Also note the transfer wheel between the barrels.



The wheels:



The two barrels:



The balance wheel with nicely concentric spring:



Another surprise and interesting feature, the pallet fork a different shape to the traditional Swiss lever:



The center seconds post is jeweled:



A quick note about the parts. I found the movement to be well made, finished and engineered however with the usual lack of decoration as we see on nearly all of Russian movements. There didn't seem to be any corners cut, the gears and teeth are all correctly formed and substantial, the only part that seemed a little rough in finish was the escape wheel teeth:





But this didn't seem to affect the performance.

Finally general shot of the parts:



 

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Congrats :-! I have already repaired several Slava 2428/2427, there are substantial differences between USSR and Russia-made pieces.

USSR-made movements have factory markings, slightly better finish, and the ring with the date levers is made in metal, not in plastic (the lever are also polished).

Russia-made movements with plastic ring, seems to have been enginereed in order to reduce the costs, to produce cheaper watches.
 

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that's really cool. very detailed tear down photos. better than most i've seen.

the pallet fork looks like some old 'swiss fake' pocket watches i've torn apart before. so that's not a too unusual design. not sure how often it turns up in wrist watches though.

and the double barrels is really neat. how does that help power reserve life? does it really make any difference in how long a wind will last?
 
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