ETA 2873

ETA 2873
ETA 2873

Description

One of the last ETA selfwindig movement, which is, unlike the 2824 familiy, already out of production, is the ETA 2873, which debuted in the 1970ies.

It is a rather simple mass production movement, but still shows the familiar ETA quality.

There's no decoration on the movement, only the oscillating weight got its checkered pattern. Technically, it doesn't matter, whether a movement is decorated or not.

movement view without oscillating weight
movement view without oscillating weight

The ETA 2873 uses the million times proved ETA selfwinding mechanism with its double click wheels. All gears, with the exception of the slowly running transportation wheel to the click wheel, are beared in rubis.

bottom view selfwinding mechanism
bottom view selfwinding mechanism

Since the oscillating weight winds in both directions and the two click gears are always driven by the weight, the click mechanism of these gears takes care, that the transmission wheel is always turned in the same direction. For that, it's always one of the click gears, which spins freely, while the click of the other ensures its power transmission.

movement view without selfwinding mechanism
movement view without selfwinding mechanism

The construction did not change since decades:

The large, here three-leg, ring balance (of course Incabloc-shock-protected) uses a hairspring, whose one end is attached to a moveable stud. Its effective length is adjusted with the hairspring key.

The movement itself uses a swiss pallet lever escapement. The center second is directly driven and there's no minute wheel, but the minute wheel on the dial side is indirectly driven by the third wheel.

This construction is used in ETA movements since the 1950ies until today!

A place, where you can see the "red pencil" is the click mechanism: It consists only of a specially shaped spring, which works on the horizontally(!) moveable crown wheel.

The different tooth types of crown wheel and mainspring wheel is neccessiary because of the selfwindig mechanism, but it can be easily imagined, that it is not a good idea to wind this watch manually every day.

main plate
main plate

The date mechanism advances the date instantly and allows manual correction on the second (of three) crown positions. The driving wheel is even jewel-beared!

dial side view
dial side view

At "8" you see the pinion of the third wheel, which indirectly drives the center minute wheel, which has to be set onto the large center axle.

At "3", you see the setting lever spring with its three positions (manual winding, date correction, time setting).

dial side view without date mechanism
dial side view without date mechanism



Technical data

ManufacturerETA
Caliber2873
Number of jewels25
EscapementAnchor with pallets
BalanceNickel
Shock protection(s)Incabloc
Balance cock directioncounterclockwise
Hairspring studmoveable
Regulator typeHairspring key
Movement constructionFork
Escapement wheel, Fourth wheel, Third wheel, Large driving wheel
Mainspring barrel
Construction typesolid construction
Winding mechanismyoke
Setting lever spring2 holes
FeaturesSCD,AUT,QG,RDR
FunctionsHour, minute, second, day, selfwinding
Beats per hour21600
Size111/2''' (measured: 25,5 mm)
Factsheet

Test Results

The movement can only with its dial into the studio and hence was completely disassembled, cleaned and oiled.

Timegrapher Protocol

On the timegrapher, this movement showed exactly, what was expected from a simple ETA mass production movement: Rock solid results in all positions with low variance. Very hard to top!

It was even possible to generate the timegrapher outputs in double precision!

dial down
dial down

dial up
dial up

12 up
12 up

3 up
3 up

6 up
6 up

9 up
9 up

Usage gallery



Links
Ranfft Uhren: ETA 2873 (de) (en) 

This movement was donated by Harald Hoeber. Thank you very much!