The UMF caliber 39-50 is one of many versions of the 8 3/4 ligne midsize movement type, called "Darling". Here in subversion 50, it only displays hour and minute, does not have a shock protection and contains only seven jewels.
It was available with screw balance as well as with a screw-less anular balance.
The "darling" caliber is a rather simple pillar construction, and when you look at the base plate, there's no indication, that it is at least a true pallet lever movement.
The UMF 39-50 has got a traditional gear train with directly driven center minute wheel, followd by third wheel, fourth wheel at 6 o'clock and escapement wheel.
Since it is a pillar construction, it builds pretty high.
The non shock protected anular- or screw balance beats slowly with 18000 A/h, but regulates a classical pallet lever movement of swiss type. With the four balance wheel bearing jewels, the elipse of the balance and and the two lever pallets, the UMF 39-50 reaches a total of 7 jewels.
On top of the main spring barrel, on its axle, there's a so-called "flitter", a flat spring. No idea, what this is good for, and also no idea, why the mainspring barrel is rather flat.
The movement itself is very lean constructed and service friendly. On the dial side, almost the whole escapement wheel can be seen, just as on skeletonized movements.
As usual for UMF, this movement has got a rocking bar winding mechanism.
The movement with screw balance and the watch, it belongs to (which still has got the old "5 Jewels" dial) is a kind donation from Mario. Thank you very much for supporting the movement archive!