Russian chronometer with constant force escapement Circa 1964

Extremely rare chronometer by the first Moscow watch factory
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An extremely rare, almost as new, small Russian 8 day chronometer “Kirowa” with “15 seconds escapement” and constant force, circa 1964.
Aluminium case. Signed silvered and numbered dial with inlaid Arabic numerals, large auxiliary seconds and blued alpha hands. Gilt 2/3 plate movement with “Geneva striping” decoration, chatoned, polished screws, cylindrical movement pillars, powered by two barrels on intermediate wheel, tandem wind with evolvent teeth, four-armed device for motion work control and winder of the constant force spring; this creates 15 second steps of the minute hand while the seconds hand runs as usual, lever escapement, monometallic balance with brass and steel screws, freesprung balance spring and chatoned diamond endstone on balance. Mahogany box with brass bezel and cushioning inlay.
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Diameter: 135 x 85 x 135 mm
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Signed: Kirowa
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Steffen Röhner documents such a 4-63 instrument no. 0034 in UHREN 3/1992; it is fitted with a monometallic balance and a Breguet spring without extra adjuster. He explains: “It seems likely that the watch was designed for special use, for example on submarines. The number 0034 points to a small series and the quality of the workmanship is excellent “, and sums up: “This Kirow chronometer of April 1963 was most likely the last wholehearted attempt at using a remontoir for improving the running of a watch.”
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Constant force escapement incorporates a remontoire device to ensure constant force between the escape wheel and the balance. The escapement of the present watch works in the following way: The upper escape wheel comes to rest on the pallet fork which is at the same level. When the balance returns the anchor recoils which has the result of putting pressure on the internal tensioning spring. At the moment that the pallet exits, this spring is released and transmits power to the lower escape wheel. This wheel then gives the impulse to the anchor. The small spring therefore gives an impulse force that is constant during the entire operation of the escapement. The constant force escapement works very well, though the timekeeping results are not as good as those for a precision pocket chronometer.