Osco 850
Description
The Osco 850 is one of the latest inhouse movements of the manufactury of Otto Schlund in Schwenningen, Germany. It is build in a pier construction with undecorated plates and a winding system, that runs partially in plastic bearings. It was probably released in the 1960ies.
base plate
The base place of the 11 1/2 ligne caliber clearly shows signs of modern and cost-efficient production, especially because of its pillar construction.
gear train
The gear train was very modern, since it did not have a center minute wheel. Because of that, the diameters for the balance and mainspring barrel could be increased, which adds to the power reserve and precision.
The indirectly driven center second is driven by a double third wheel.
side view of the gear train
The modernly shaped ring balance is secured by two KIF Trior systems beats slowly with 18000 A/h. There’s already a moveable hairspring stud for reducing the beat error. The frequency can be adjusted at the hairspring key only.
Ratchet
The ratchet is a nice example for perfect functionality but low costs. It only consists of the simply made click and the spring. Both are located beyond the ratchet wheel, only the end blocks it.
empty dial side
On the empty dial side, you can see the yoke winding system.
dial side without date indication
The date mechanism consists of a switching wheel with moveable finger. It enables half-speed quickset by turning the time back and forth:
date indication mechanism
Normally, you cannot see the date indication mechanism, since it is covered by a plate.
Osco 850 dial side
In the lab
Timegrapher result
The timegrapher result indicates, that there’s need for a service, especially due to the low amplitudes.| horizontal positions | |||
|---|---|---|---|
| dial up | -52 s/d | 158° | 0.0ms |
| dial down | +50 s/d | 199° | 0.1ms |
| vertical positions | |||
| crown right (12 up) | -23 s/d | 159° | 0.0ms |
| crown up (3 up) | +34 s/d | 165° | 0.0ms |
| crown left (6 up) | -15 s/d | 169° | 0.8ms |
| crown down (9 up) | +25 s/d | 153° | 0.9ms |
Technical data
| Manufacturer: | Osco |
| Caliber: | 850 |
| Size: | 11 1/2''' (measured: 25,2mm) |
| A/h: | 18000 |
| Number of jewels: | 17 |
| Escapement: | Pallet lever |
| Balance types: |
Nickel anular balance |
| Shock protection(s): |
KIF Trior |
| Balance bearing / direction hairspring: | Clockwise |
| Moveable stud: | yes |
| Adjust mechanism: | Hairspring key |
| Construction: |
|
| Construction type: | pillar construction |
| Winding mechanism: | yoke winding system |
| Setting lever spring: | 2 hole(s) |
| Features: |
|
| References: |
Flume: K3 44 |
| Inventory number: | 17030 |
Usage gallery
Prätina gents' watch
Osco S gents watch