Before Oris became popular for their “High Mech” line with ETA movements, they produced inhouse movements for many decades, mainly pin lever movement in different qualities.
One of their early movement, which was quality-wise rather on the lower end, is the caliber 90P shown here, a simple but rugged pin lever movement in Roskopf construction.
The simple brass plate uses no jewels, only drilled brass bearings and two steel bearings for the balance staff.
The way, the winding wheel is held in position is really freaky: The upper gear train bridge is slanted below the crown wheel and bent down, so that the winding wheel cannot move lateral:
The clutch wheel and the winding stem are beared in a metal cage, which became porous over the years. On the following photo, you see, that half of the cage is mising:
The gear train is typical for a Roskopf construction:
The large mainspring barrel overtops the center of the movement, and is followed by the second wheel, third wheel and escape wheel.
Compared with “normal” lever movements, it has got one less transmission step.
Due to the missing transmission stage, the beating rate has got the odd amount of 17280 beats per hour, which can be adjusted as far, as technically possible, with a long regulator arm. The not shock protected anular balance has got a rugged balance staff. It engages with a pin lever.
The lever is pretty simple and only punched, but has got a beautiful shape.
As with any Roskopf construction, the hands are driven exclusively on the dial side by the double gear, which sits, connected with a slip clutch, on top of the mainspring barrel.
The lower, larger sprocket drives the small minute tube with the minute hand on, the small upper sprocket the big hour wheel.
It’s a bit surprising, that the Oris 90P already uses a yoke winding system. The hands setting wheel engages here with the large sprocket of the double gear on top of the mainspring barrel.
At 7 o’clock, you can see the cutout for the lever bearing. With some force applied, it can be “adjusted”, so that the lever pins engage properly with the escape wheel. A pragmatic, but efficient solution.
In the lab
Nickel anular balance|
|Balance bearing / direction hairspring:||Counterclockwise|
|Adjust mechanism:||Long regulator arm|
|Construction type:||pillar construction|
|Winding mechanism:||yoke winding system|
|Size:||13''' (measured: 29,3mm)|