ETA 853

Description

With a diameter of 31.4cm (14 lignes), the ETA 853 not only belongs to the larges movement, which ETA ever made, but also to the largest movements, which were used in contemporary wristwatches.

The execution of this movement from the late 1049s is very well. It is a massive construction, has got a large mainspring barrel and of course uses in all important bearings rubies.

The gear train with its classical execution is like from a textbook.

The mainspring barrel drives the center minute wheel, followed by third wheel, seconds wheel at 6 o’clock (with prolonged axle on the dial side to carry a seconds hand) and steel escape wheel.

Because of the large size of the movement, the gears look very filigree in comparison.

The ETA 853 uses a monometallic screw balance as regulating device.

As usual at that time, it is not shock protected and beats with 18000 A/h. A long regulator arm is used to adjust it.

A funny detail of the specimen shown here is, that is lever has got to differently colored pallets. While they look interesing, it should not have any technically effect.

Nice and tidy looks the dial side, on which you can see the yoke keyless works.

Around 1 o’clock, you can see a few minute markers. They were used to allow a regulation of the raw movement without the need for a dial.

In the lab

Timegrapher result

The rates are not really well, without spare parts, it is unlikely, that they improve.
The amplitude values are missing here, because they were mistakenly traced with 52° instead of the correct 44° lift angle.