ETA’s 2892 was an ultra-thin automatic watch movement and the first in the ETA 2890 family. It was introduced in 1975, as Eterna’s movement operations were folded into ETA, and removed from production in 1983. The ETA 2892-2 was the successor movement.
Closely related to the short-lived Eterna 1504, the ETA 2892 operates at 28,800 A/h, has 17 or 21 jewels, and features an automatic winding system embedded into the movement rather than attached above it. This system, which uses ball bearings, was called “Etarotor” at the time. This gives it the signature 3.6 mm depth which remains the hallmark of the family to date.
The coverage in Europa Star at the time of launch claimed that this was the “flattest calibre in the world to be manufactured on an industrial scale.” WatchTime claims that ETA produced 342,123 examples of Cal. 2892 between 1975 and 1983.
The ETA 2892 and closely-related ETA 2890 (no date) measured 12.5”’ (28.0 mm) in diameter. The oscillating weight extended to the edge of this plate, effectively winding the stiff mainspring needed to drive the high-beat 28,800 A/h balance.
Note that some sources, including reputable magazines like WatchTime, list the diameter of Cal. 2890 at 11.5 ”’ (25.60 mm) like the successor ETA 2892-2 and 2892A2, but this is incorrect. Official ETA documentation shows the diameter as 12.5 ”’ (28.00 mm).
ETA 2890 Family Overview
The ETA 2890 family is a series of slim and robust automatic watch movements produced by ETA. They are generally regarded as superior to the similar ETA 2800 family. Cal. 2890 and its successors is based on the Eterna 1466U, with ball bearings on the rotor and a smaller balance wheel in the modern style. Launched in 1975, the family remains one of the leading watch movements to this day.
The most well-known movement in this series today is Cal. 2892A2, a highly evolved automatic movement with central seconds and a date wheel. Because of its slim dimensions, Cal. 2892A2 is often paired with modules to add world time, power reserve indicator, chronograph, and other complications.
Distinguishing features of the ETA 2890 family include a smaller balance wheel than historic movements, including the ETA 2824 family, and a large rotor hub located with seven visible bearings. The balance is located at 12:00 when viewed from the back with the crown at 9:00, and is located by a clockwise cock with an eccentric screw for regulation.
Most members of the modern 2890 family are available in there finish levels:
- Elaboré – with nickel balance
- Top – with Glucydur balance
- Chronomètre – with Glucydur balance and official chronometer certification
ETA also sells these movements with gold plating, various finishes, and custom rotors.