Unitas Caliber 431

Unitas Caliber 431

Unitas Caliber 431

Manufacturer Unitas
Caliber Number 431, UT431, 431-445
Movement Type Mechanical, manual-wind
Lignes 18.5”’
Jewel Count
Seventeen (17)
Beat Rate
18,000, 2.5 Hz
Lift Angle
43 degrees (unconfirmed)
Power Reserve
~41 hours
Hand Count 3
Hands Sizes
2mm / 1.15mm / .26mm
Functions Central hours; central minutes; small running seconds subdial at 6:00 (with open face design lepine style watch cases)
Hacking Seconds?
Country of Manufacture Switzerland, Swiss made
Known Models
Waltham pocket watch (Add your watch to the comments below…)

The Unitas caliber 431 is a large handwound mechanical pocket watch movement. This calibre is considered to be a larger version of the popular ETA/Unitas 6497. Circa 1940s ~ 1960s (unconfirmed).

431 VS 6497:

*Check back soon for side-by-side images.

You may be wondering if the 431 is more closely related to the 6497 or 6498, since the small seconds hand is at 6:00. Keep in mind, that this is a pocket watch movement, and the seconds hand is at 6:00 with the crown at 12:00 (lepine style). If this movement is in a hunter style pocket watch case (with the crown at 3:00), the everything rotates clockwise 45 degrees to place the small seconds at 9:00 – hence the comparison to the 6497.

Learn More: ETA/Unitas 6497 VS 6498 Differences

Macro Gallery:

Unitas Caliber 431 Balance Wheel Anti Schock Device

Unitas Caliber 431 Bridge

Unitas Caliber 431 Wxo Engraving

Unitas Caliber 431 Ratchet Wheel Click

Unitas Caliber 431 Macro

Unitas Caliber 431 Calibre Number

Watches with this caliber:

The Unitas 431 example featured in this caliber listing was found in this Waltham pocket watch from the 1960s – possibly during the time in which Waltham Watch Co. was acquired by “a Swiss group headed by the Invicta Watch Co.” (source).

Unitas 431 Waltham Pocket Watch

Additional Resources:

Seagull Caliber St19

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