IWC 431

 
IWC 431

IWC 431

Description

In  the 1950ies, it was en vogue, that ladies’ watches had to be as small as possible. From that very time originates the form movement IWC 431 with it’s really small size of 4 34 lignes (11.6 x 14.9 mm).

base plate

base plate

The base plate of this form movement shows, that the balance wheel and the mainspring barrel have as much place as possible, nevertheless, there’s quite a lot of wasted space, for example next to the mainspring barrel.

gear train

gear train

All fast turning gears (escapement wheel, fourth and third wheel) are ruby beared, especially the large golden toned Glucydur screw balance. The balance beats relatively fast with 19800 A/h and is secured in two Incabloc shock protection bearings.

side view of the gear train

side view of the gear train

The gears are of a very high quality, and the rest of the movement gives a really pleasent view with its decorations!

gearing of the winding system

gearing of the winding system

A speciality of that movement is, that the crown wheel does not directly drive the ratchet wheel, but uses two intermediate wheels, the first one with a slanted toothing. I don’t know the reason for that construction and why the crown wheel wasn’t made larger to engage directly with the ratchet wheel.

Detail: Click spring

Detail: Click spring

The click spring is a very clever construction: It is completely located under the ratchet wheel and consists of only one piece including a flat ball joint. Only an additional spring is used to hold the click in position. So, this is a clever, space and cost saving construction, which works very efficiently.

IWC 431 dial side

IWC 431 dial side

The dial side with its beading and the IWC hallmark gives a beautiful view. The helical toothing of the clutch wheel can also be seen here. Only few high quality movement offer this!

In the lab

The specimen shown here was pretty sure taken off a melted gold watch, and since it was still ticking, no service was made.

Nevertheless, the technical condition of the movement is pretty poor, on the timegrapher it showed bad results, which are not representative for that movement, so they aren't shown here.

Technical data

Manufacturer:IWC
Caliber:431
Number of jewels:17
Escapement:Pallet lever
Balance types: Glucydur screw balance
Shock protection(s): Incabloc
Balance bearing / direction hairspring:Counterclockwise
Moveable stud:no
Adjust mechanism:Long regulator arm
Construction:
  • lever
  • escape wheel, seconds wheel
  • third wheel, center minute wheel, mainspring barrel
Construction type:solid construction
Winding mechanism:yoke winding system
Setting lever spring:3 hole(s)
Functions:hour, minute
A/h:19800
Size:4 3/4''' (measured: 11,6 x 14,9mm)
Literature: Flume: K2 -
Inventory number:17007

Usage gallery

IWC ladies' watch  (from 1955, case missing)

IWC ladies' watch (from 1955, case missing)