Osco 107

 
Osco 107

Osco 107

Description

In the late 1950ies, Otto Schlund (Osco) launched the movement family 100, a series of 10 12 ligne movements with different features and swiss pallet lever escapement and a screw less anular balance, which was very modern at that time.

The Osco 107 shown here is the sister movement of the Osco 108, lacking the date indication feature, but instead it has got a decentral seconds indication a 6 o’clock.

base plate

base plate

This movement is a pillar construction; the ratchet is on the dial side.

It uses only eight jewels, four for the balance wheel bearing, one for the ellipse, one for the movement side bearing of the escapement wheel and two jewels of the lever pallets.

gear train

gear train

We’ve got a classical one-storey construction, almost a bit old-fashioned at that time, but often used, escpecially on simpler movements.

side view of the gears

side view of the gears

The screw-less anular balance has got two slightly waisted legs and is beared in two Monorex shock protections. It beats slowly with 18000 A/h.

Osco 107 dial side

Osco 107 dial side

On the dial side, you can easily spot the rocking bar winding mechanism and the ratchet. The latter one has got a genious spring construction:

ratchet

ratchet

The spring is held in place by the ratchet screw and interferes with the dot on top of the ratchet. The big advantage of this construction is, that you don’t have a flying spring here. The downside is, that a broken spring requires a spare part of the manufacturer.

In the lab

The specimen shown here was in a watch, which shows many signs of heavy use, there are even deep scratches on the dial.

Nevertheless, right from the start it showed a very good performance, slightly too fast, so that a service was not neccessiary. After disassembly, it was slightly oiled and adjusted.

Timegrapher result

The rates are really good for a movement without service, only the bad balancing of the balance wheel and the resulting positional errors are a bit bad. But it nevertheless shows a perfect line on the timegrapher!

horizontal positions
dial up +2 s/d 243° 0.4ms
dial down +28 s/d 231° 0.4ms
vertical positions
crown right (12 up) -30 s/d 190° 0.4ms
crown up (3 up) +20 s/d 202° 0.1ms
crown left (6 up) +19 s/d 200° 0.8ms
crown down (9 up) -32 s/d 195° 1.0ms

Technical data

Manufacturer:Osco
Caliber:107
Number of jewels:8
Escapement:Pallet lever
Balance types: Nickel anular balance
Shock protection(s): Monorex
Balance bearing / direction hairspring:Clockwise
Moveable stud:no
Adjust mechanism:Hairspring key
Construction:
  • lever
  • escape wheel, seconds wheel, third wheel, center minute wheel
  • mainspring barrel
Construction type:pillar construction
Winding mechanism:rocking bar winding system
Setting lever spring:2 hole(s)
Functions:hour, minute, decentral second
A/h:18000
Size:10 1/2''' (measured: 23,2mm)
Literature: Flume: 1958 35

Usage gallery

Osco 107 gents watch

Osco 107 gents watch