Felsa 760

Description

A pretty hard to find movement is the Felsa 760, also known under its name “Permutator”, which offers a power reserve indication.

Like all Felsa movements, this one is a high quality movement, too, where all important bearings contain rubies, even the minute wheel bearing.

With the bearings of the selfwinding mechanism, the Felsa 760 offers 30 jewels in total, an impressive number.

The center minute wheel was still more or less state of the art in the early 1960s, when this movement was launched. Its large base plate allowed a large mainspring barrel, though.

Das zentrale Minutenrad war Anfang der 60er Jahre, als dieses Werk auf den Markt kam, durchaus noch Stand der Technik, und die große Grundplatine erlaubte trotzdem ein sehr groß dimensioniertes Federhaus.

Yet another movement with the classical gear train: The mainspring barrel drives the centerminute wheel, followed by third wheel, seconds wheel and finally the escape wheel.

The center seconds pinion is driven indirectly by the double third wheel.

The double third wheel is responsible for a flutter-free driving of the center seconds pinion.

In the version shown here, the Felsa 760 uses a golden colored Glucydur screw balance with two legs, beared in two Incabloc shock protections. This combination was the best, you could get on the mass market.

It still beats slowly with 18000 A/h, and it can be fine-adjusted with a long regulator arm.

To save space for the selfwinding mechanism without negative influence of the height, the crown wheel was put onto the inner side of the gear train bridge. The ratchet of the mainspring is located on the very outside of the movement, also for height-reducing purposes.

The caliber 760 uses the proven “Bidynator” selfwinding mechanism, where a lever changer and a ratchet on the leftmost gear ensures, that no matter in which direction the oscillating weight turns, the gears always work in the same direction and wind the mainspring.

The final gear has got a commutator clutch (broken in the image), which decouples the selfwinding mechanism, when the movement is wound manually.

The lever changer and the three gears of the selfwinding mechanism are ruby-beared.

The oscillating weight is axle-beared and contains a ruby bearing.

There are two concentric axles, coming from the mainspring barrel, seen at position 12:30 o’clock.

The first one is connected with the bottom of the mainspring barrel and carries a tiny gear, the second axle is connected with the inner spring and carries a square.

The power reserve indicator is a rather simple mechanism, which measures the differences between the two axles and so the tension of the mainspring. After two following reduction stages, the maximum difference is only 270 degrees and so, the final wheel can carry the indicator hand (broken in the specimen shown here).

Since the mainspring barrel contains a slipping clutch, the mechanism must take into account, that you can wind it eternally. For this, the power reserve mechanism contains a slipping clutch, too, and a gear, which blocks after 270 degrees.

The other parts on the dial side are far less spectacular: Yoke winding system and Incabloc shock protection are standard, and the cap jewel of the escape wheel, also on the movement side, are in indication of the high quality of this movement.

The Felsa 760 offers a simple date indication mechanism, where a spring loaded metal disc is responsible for locking the date ring. This construction is easier to work with on a revision, because it has got no easily flying hands and levers.

Technical data