The Jeambrun 23D, a handwound movement of the fifties, which was used quite often, originates from
France, from the village of Maîche of the departement Doubs near the northwest swiss border.
It was available in several versions, which differed by their decoration, the number of used jewels
and shock protection systems.
All in common is the unusual construction, where the mainspring barrel is located at "6" and the balance
is located at "12". Hence the barrel arbour wheel is located to the right of the crown wheel and not,
as usual, at the left.
version with 17j
The golden toned Glucydur screw balance was beared in different shock protection systems,
such as Incabloc, Ruby-Shock and others.
The hairspring is fix mounted at the balance cock and can be regulated in its effective length with
the help of a long regulator arm. This helps slower beating watches (with 18000 A/h) to achive good
timing results.
movement view without mainspring barrel
The train construction is pretty modern with its directly driven center second indication.
train mechanism
The minute wheel is located under an own bridge - pretty modern for the fifties. For a perfect
bearing of the concentric second wheel, a loose(!) ruby was put onto the bridge.
detail: lose center second wheel bearing jewels
Of course, all bearings, except the mainspring barrel bearing, contain synthetic rubis. It the
more elaborate version, even 6 of them have got cap jewels on their top. More functional rubis are
hardly possible.
main plate
On the dial side, you see the yoke winding system with its characteristic setting lever
spring, which contains only two holes.
dial side view, 23j version
As usual on those old movements, the Jeambrun 23D contains a helping minute scale, which
can be used for timing the watch without timegrapher.
dial side view, 17j version
Technical data
Manufacturer
Jeambrun
Caliber
23D
Number of jewels
17/23
Escapement
Anchor with pallets
Balance
Glucydur screw balance
Shock protection(s)
Ruby-Shock,Incabloc
Balance cock direction
clockwise
Hairspring stud
fixed
Regulator type
Long regulator arm
Movement construction
Fork Escapement wheel, Fourth wheel, Third wheel Center wheel Mainspring barrel
