Over the lifespan of the Vacheron Constantin 4072, 1938 until 1970, three movements were used, all based on the Valjoux 22 (production information listed when known):
– 13′ V295
— 24 produced in yellow gold [1]
– 13′ V434
— Under 250 produced in steel [2]
– 13′ V492
These movement were listed as ‘VZ’ instead of the correct ‘V’ (Valjoux, the supplier of the ebauche), as I show, above.
You may read that the Vacheron Constantin 4072 only utilized the 434 and 492, but the 295 was also used by this reference. The 295 will only be found in the earliest pieces, such as (262237) as seen in the Vacheron Constantin 4072 case number project. I believe that the V295 had a 30 minute register, whereas the V434 and V492 both feature a 45 minute register.
With so few pieces, I have not found any steel Vacheron 4072 movement images with the 434 or 492, so I have used examples from gold 4072 at roughly the same serial number. The Cal 295, below left, is from 262237.
[1] Phillips, The Geneva Watch Auction: TWO, Geneva Auction 7 & 8 November 2015, Lot 129
[2] Vacheron Constantin marketing information, June 2020