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Discussion Starter · #1 ·
hello all, Just joined the forum, I have a Zenith Tank watch, need more info on the movement, picture attached, Thanks IMG_20170529_143946331.jpg
 

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It looks like some sort of N.V.S.I movement from ca. 1935. The exact specification will depend on size, e.g. a 13''' movement (ca. 30mm across) would be a Cal. 13''' N.V.S.I (later designation 13'''-2 where the -2 denotes a savonette or "hunter" movement).

Hartmut Richter
 

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Discussion Starter · #3 ·
Thanks Hartmut, Sorry but I don't know what N.V.S.I means? were these in house movements during those days? this one comes form a 18K tank case.
 

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nobody knows what's behind NVSI acronym, at least that's what's written in the Rossler's book
they are in house for sure :)
 

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Discussion Starter · #7 ·
the diameter is 20 mm, does that point in any direction?

It looks like some sort of N.V.S.I movement from ca. 1935. The exact specification will depend on size, e.g. a 13''' movement (ca. 30mm across) would be a Cal. 13''' N.V.S.I (later designation 13'''-2 where the -2 denotes a savonette or "hunter" movement).

Hartmut Richter
 

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That small? In that case, in view of the distantly spaced screws on the mainspring bridge (the ones right next to the balance cock), it must be a Cal. 10 1/2''' N.S.I (later designation 10 1/2'''-2). Made in 68400 pieces between 1926 and 1937 so yours is one of the later ones. Interestingly enough, there doesn't seem to be a lepine version of this movement (no Cal. 10 1/2'''-1). 10.5''' is 23.7mm across which is what yours measures. On the older pocket watch movements, there is a hidden lip which helps retain the movement in the case so that, if you took yours out, you'd see that it is a little bigger than what you measured.

Hartmut Richter
 

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Discussion Starter · #9 ·
nobody knows what's behind NVSI acronym, at least that's what's written in the Rossler's book
they are in house for sure :)
Information about The N.V.S.I initials completing the number of lines of the caliber in question refer to the first (I.) version of the New variant of this caliber, adaptable to Lepine watches (or “open-face” watches, showing the dial and its glass (“Verre” in French) directly), as well as to Hunter (“Savonnette”) watches.
These initials could thus be combined in various ways, to designate each time a specific version of Zenith main caliber from the first half of the 20[SUP]th[/SUP] century.
 

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Interesting. They must have found the missing information since Rössler wrote his book. But it does make sense: the 10 1/2''' N.S.I doesn't have a lepine version (as I noted previously) - and the "V" is missing in the designation!

Hartmut Richter
 
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