Felsa 790

 
Felsa 790 (oscillating weight and axle missing)

Felsa 790 (oscillating weight and axle missing)

Description

The Felsa 790, here in red-golden color, debuted in the mid 1950ies and is compareatively rare; probably Felsa produced it in lower quantities than the caliber 1560, which was made at the same time.

base plate

base plate

As all Felsa movement, the Felsa 790 is very well made, too.

All important bearings use rubies.

base plate with minute wheel

base plate with minute wheel

The classical gear train construction requires a center minute wheel, which is directly driven by the mainspring barrel. It is beared below an own bridge.

gear train

gear train

The rest of the gear train is pretty much standard: The central minute wheel drives a double third wheel, which engages with both gears into the center seconds pinion and with the lower of the two gears into the seconds wheel. Because of this, the center seconds wheel does not flap.

third wheel

third wheel

The final wheel is, as expected, the escape wheel, made of steel. It is blocked by a swiss pallet lever escapement.

side view of the gear train

side view of the gear train

The golden Glucydur screw balance is really beautiful!

It beats slowly with 18000 A/h and can be regulated with a long regulator arm.

The balance wheel is shock protected by two Incabloc bearings.

inside the gear train bridge

inside the gear train bridge

A little speciality of the Felsa 790 construction is the crown wheel: It is located on the inner side of the gear trian bridge, which also bears the mainspring barrel.

w/o selfwinding mechanism

w/o selfwinding mechanism

The tiny ratchet is located at the outer edge of the base plate and is pushed with a spring against the ratchet wheel.

selfwinding gear train

selfwinding gear train

Felsa kept the “Bidynator” principle: The oscillating weight drives the transmission wheel of the lever changer. Depending on its direction, it drives either the left of the right large exchange wheel. The pawl of the left exchangle wheel ensures, that only revolutions in one direction are possible.

ratchet wheel

ratchet wheel

After the right exchange wheel, a reduction wheel with a ratchet clutch is used to drive the ratchet wheel of the mainspring barrel and to release it, when the movement is manually wound.

selfwinding gear train, side view

selfwinding gear train, side view

The oscillating weight, which unfortunately is missing on the specimen shown here, is axle beared. The axle is mounted with three screws on top of the gear train bridge.

Felsa 790: Dial side

Felsa 790: Dial side

On the dial side, you see the yoke winding system, the Incabloc shock protection and a partial minute scale, which was used to adjust the movement prior to casing.

Technical data

Manufacturer:Felsa
Caliber:790
Size:11 1/2''' (measured: 26,0mm)
A/h:18000
Number of jewels:22
Escapement:Pallet lever
Balance types: Glucydur screw balance (two legs)
Shock protection(s): Incabloc
Balance bearing / direction hairspring:Clockwise
Moveable stud:no
Adjust mechanism:Long regulator arm
Construction:
  • lever
  • escape wheel, seconds wheel, third wheel, center second pinion, mainspring barrel
  • center minute wheel
Construction type:solid construction
Winding mechanism:yoke winding system
Setting lever spring:3 hole(s)
Features:
  • SCI (indirect center seconds)
  • AUT (selfwinding)
Literature: Flume: 1957 57
Inventory number:20047

Usage gallery

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