With 130 million items, the UMF caliber 24, which debuted in 1963, is one of the most successful pin lever caliber families ever. It was made until the late 1980s and in its best times, more than 25.000 movements were made each day.
It had the standard size of 10 1/2 lignes and during its more than 25 years in production, it was made in several versions. The german Watch Wiki has got a very good overview over the versions.
The base caliber, UMF 24-30, was only capable to show hours and minutes.
The base plate is stamped and a little higher in the middle. There are no bearing jewels on this pillar construction. At position 1 o’clock, you can see the ratchet, which is its own spring at the same time.
The gear train is typical for a pin lever movement, whose roots date back to the 1920s: Mainspring barrel, directly driven center minute wheel, third wheel, seconds wheel at 6 o’clock and finally the escape wheel.
As you can see, this pillar construction builds pretty high, probably a cause, why this movement, even when it is in good condition, shows bad results on the timegrapher.
The simple three-leg anular balance beats slowly with 18000 A/h. It is not shock protected and can be regulated with two slipping clutches, one for the moveable hairspring stud (starting with version B in 1975) and one for the hairspring key. It is very difficult to adjust them seperatly.
On left of the dial side, there’s the screwed-in balance bearing, which allows the height-regulation of the balance wheel axle, and on the right, you see the yoke keyless works. The ratchet is located on the inside of the main place, as told above.
Starting with the version E, which was made from 1976, the yoke was made in plastic.
|Size:||10 1/2''' (measured: 23,6mm)|
Nickel anular balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Hairspring key|
|Construction type:||pillar construction|
|Winding mechanism:||rocking bar winding system|
|Setting lever spring:||2 hole(s)|
Flume: K3 66|