ETA 2651

Description

The ETA 2651 is the slower beating variant of the familiar ETA 2671. Unlike its sister caliber, it works with six instead of eight alternations per second.

All movements of this series have got the same small diameter of only 7 3/4 lignes and wer launched in the 1970ies, when ladies' watches had to be as small as possible.

As on all better movements, all important bearing contain synthetic rubies, except for the bearing of the center second. Additionally, the mainspring barrel is ruby-beared on the dial side.

Since the selfwinding module uses no rubies, the total number of that movements stays at seventeen, which is pretty low for a selfwinding movement.

As you can see, the mainspring barrel and the balance wheel have lots of place, while at the same time, the gear train is very compact and uses only little place.

The gear train is still state of the art, altough that kind of construction was already introduced in the 1950ies.

The mainspring barrel drives the second wheel, followed by third wheel, center second wheel and escape wheel. The third wheel drives the minute wheel on the dial side, which contains a slip clutch.

The space-saving construction of the gear train lets lots of space available in the movement.

The three-leg anular balance is beared in two Incabloc shock protections and beats with rather moderate 21600 A/h. The long regulator arm on the balance cock is used to adjust the beat frequency.

Particularly striking is the free space that the gear train construction offers, when the selfwinding module is not yet mounted.

The crown wheel is, as you can see, mounted moveable on an ellipse-shaped bearing. The ratchet spring, which engages with the crown wheel, shifts it in the direction of the ratchet wheel.

The reason, why the crown wheel is moveable, is unknown, especially, since the winding stem has got a breguet clutch, and additionally, there’s no decoupling of the selfwinding module at all.

The selfwinding gear train consists of four gears: Two change wheels (with pawls), which engage with the oscillating weight, and two reducer wheels.

During manual wind, the two pawl changers are responsible, that the oscillating weight is decoupled. Nevertheless, the force during manual wind, which impacts these fast revolving gears, is enormous.

On the inner side of the selfwinding module, you can spot the pawls on the changer wheels. Besides the decoupling of the oscillating weight, their main function is, to ensure, that the oscillating weight winds in both directions.

This construction is used by ETA, starting from then 1950ies till today.

On this ETA 2651 specimen, the oscillating weight in axle-beared, but there also exist versions with a ball bearing.

On the still empty dial side, you can see, how the hands are driven at 7:30 by the third wheel. The minute wheel is rather large and carries the cannon pinion with a slip clutch.

This construction requires, that the setting wheel cannot engage with the minute wheel, but with the changer wheel, which engages with both, the cannon pinion for the minnute hand and the hour wheel.

The ETA 2651 uses an instant switching calendar. The switching wheel at 10 o’clock has got a moveable finger, which is tensioned between 8 pm and midnight. At midnight, it abruply unloads and advances the date ring one step.

This movement has also got a quickset mechanism: On the middle crown position, the tiny switching wheel at 4 o’clock enages with the moveable setting wheel, which is now released from the engagement with the changer wheel. The three fixed switch fingers advance the date ring.

This calendar mechanism sounds rather complicated but it is astonishingly service friendly and works absolutely reliable.

Technical data

Usage gallery