Osco 850

Osco 850 | 17jewels.info - The Movement Archive

Osco 850


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.

Osco 850: base plate

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.

Osco 850: gear train

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.

Osco 850: side view of the gear train

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.

Osco 850: 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.

Osco 850: empty dial side

empty dial side

On the empty dial side, you can see the yoke winding system.

Osco 850: dial side without date indication

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:

Osco 850: date indication mechanism

date indication mechanism

Normally, you cannot see the date indication mechanism, since it is covered by a plate.

Osco 850: Osco 850 dial side

Osco 850 dial side

In the lab

The specimen shown here came in good condition into the lab, only the mainspring was broken and replaced. No cleaning or service was made.

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

Size:11 1/2''' (measured: 25,2mm)
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
  • lever
  • escape wheel, seconds wheel, third wheel, large driving wheel, center second pinion
  • mainspring barrel
Construction type:pillar construction
Winding mechanism:yoke winding system
Setting lever spring:2 hole(s)
  • SCI (indirect center seconds)
  • QG (date indication (aperture))
References: Flume: K3 44
Inventory number:17030

Usage gallery

Osco 850: Prätina gents' watch

Prätina gents' watch

Osco 850: Osco S gents watch

Osco S gents watch

This movement including the Prätina watch is a kind donation of U.Bohnet-Ströbel. Thank you very much for the support of the movement archive!