Ebosa 86

Ebosa 86 | 17jewels.info - The Movement Archive

Ebosa 86


The Ebosa 86 is a midsize ladies' watch manual wind movement with a diameter of 8 3/4 lignes, that’s about 20mm.

It was available in a number of versions, which differed by the features (with or without center second) and in the execution (1, 17 and 21 jewels).

Ebosa 86: 17j version

17j version

The base plate of the 17j versions looks already pretty beautiful, although it is only a pillar construction.

Ebosa 86: base place (17 jewels)

base place (17 jewels)

The gear train is the same on all version. Like on a Roskopf watch, the large mainspring barrel covers the center of the movement and drives only the gear train on the movement side, and not the time works.

The mainspring barrel follow second wheel, third wheel and escape wheel.

Unlike on “true” Roskopf movement, there the classical beat rate of 18000 A/h is used.

Ebosa 86: gear train (17 jewels)

gear train (17 jewels)

The version with center second has got a central seconds wheel, whose outer gears engage into the outer gears of the third wheel. The center second gear is riveted to the base plate and cannot be taken off.

Ebosa 86: side view of the gear train (17 jewels)

side view of the gear train (17 jewels)

The 17 jewels version has got a non shock protected anular balance, which is pivot beared and thus sensitive against shocks. The one-jewelled version has got a solid conical balance staff, which is beared in Beryllium-bronce conical bushes and does not need an additional shock protecion.

In both cases, the balance uses a ruby ellipse.

As common on pin lever movements, the pin lever has got a long axle and is beared under an own cock.

Ebosa 86: Ebosa 86: Dial side

Ebosa 86: Dial side

Since the Ebosa 86 is a Roskopf construction, the hands are all driven on the dial side by a double clip clutch gear on top of the mainspring barrel. The two gears simultaneously drive both hands, so that no further changeing wheel is required.

Ebosa 86: Ebosa 86: Dial side (17 jewels)

Ebosa 86: Dial side (17 jewels)

The yoke winding mechanism is unusual for such a simple movement, and its construction with the spring integrated into the end of the yoke and the very simple constructed holding of the clutch wheel is hardly anywhere else seen. It is certainly constructed for price, not for longevity.

Technical data

Size:8 3/4''' (measured: 19,8mm)
lift angle:63°
Number of jewels:1/17
Escapement:Pin lever
Balance types: Nickel anular balance
Shock protection(s): none
Balance bearing / direction hairspring:Counterclockwise
Moveable stud:no
Adjust mechanism:Hairspring key
  • lever
  • escape wheel, seconds wheel, third wheel, mainspring barrel
  • center second pinion
Winding mechanism:yoke winding system
Setting lever spring:1 hole(s)
  • SCI (indirect center seconds)
References: Flume: K2 -
Inventory number:18030

Usage gallery

Ebosa 86: Davar ladies' watch

Davar ladies' watch

Ebosa 86: Borea ladies' watch

Borea ladies' watch