Jeambrun 23C

 
Jeambrun 23C

Jeambrun 23C

Description

The Jeambrun 23C is one of the last french cylinder movements and was made probably in the 1940ies. With its brige shape and the stripes decoration is appears quite modern, but technically it was already out of date, when it was made.

base plate

base plate

Even when the Jeambrun 23C was probably quite cheap at that time, its execution with a non-pillar construction and bearing rubies for balance and escapement wheel weren’t usual for low-end movements at that time.

gear train

gear train

The gear train is typical for a cylinder movement: The non shock-protected annular balance beats slowly with 18000 A/h, and its cylinder controls the flat cylinder wheel with its sharp teeth, which is located beyond an own cock.

That wheel are following fourth wheel (for the subseconds indication a “6 o’clock”), second wheel and the center minute wheel, all directly driven.

side view of the gear train

side view of the gear train

The advantage of a cylinder movement over a lever movement is, that not only one critical part (the lever) is saved, but due to the much larger fourth wheel, one transmission step less is used, so there’s no need for a third wheel.

The disadvantage (and the reason, why those movements are obsolet) ist, that the precision is pretty bad since the sharp teeth of the cylinder wheel always stay in contact with the metal cylinder of the balance, preventing the balance from swinging freely. And additionally, this construction is very prone to magnetism.

Jeambrun 23C dial side

Jeambrun 23C dial side

On the dial side, there’s only a rocking bar winding mechanism with a very simple ratchet, which consists only of a spring, that intervenes directly with the teeth of the mainspring barrel.

Technical data

Manufacturer:Jeambrun
Caliber:23C
Number of jewels:7
Escapement:Cylinder
Balance types: Nickel anular balance
Shock protection(s): none
Balance bearing / direction hairspring:Clockwise
Moveable stud:no
Adjust mechanism:Long regulator arm
Construction:
  • center second pinion
  • seconds wheel, third wheel, center minute wheel
  • mainspring barrel
Construction type:solid construction
Winding mechanism:rocking bar winding system
Setting lever spring:3 hole(s)
Features:s
Functions:hour, minute, decentral second
A/h:18000
Size:10 1/2''' (measured: 23,2mm)
Literature: Flume: K1 -

Usage gallery

anonymous mens' watch around 1940

anonymous mens' watch around 1940

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