Bifora 910/1

Bifora 910/1 | - The Movement Archive

Bifora 910/1


In 1962, Bifora launched the cost-optimized caliber series 91, which contained among other movement the Bifora 910/1 shown here. It has got an enlarged base plate, a larger mainspring barrel and a date indication.

Construction-wise, it is a pillar construction without decorative elements, but it was so reliable, that it was made until 1980.

Bifora 910/1: base plate

base plate

All important bearings are contain rubies, even the one of the minute wheel.

You can clearly see, how the base plate was enlarged from 9 3/4 lignes before to 11 1/2 lignes, which is the standard size for a gents' movement.

Bifora 910/1: minute wheel bridge

minute wheel bridge

This movement has got the oddity, that the keyless works is mounted onto the minute wheel bridge, and not on the dial side.

Bifora 910/1: base plate with center minute wheel

base plate with center minute wheel

On the minute wheel cock, there’s also a spring, which saved the center seconds indication from fluttering by applying a little bit of friction onto its pinion.

Bifora 910/1: gear train

gear train

We have the classical gear train with directly driven center minute wheel, third wheel, seconds wheel at 6 o’clock and the filigree steel escape wheel.

The center seconds pinion has got the same amount of teeth as the pinion of the seconds wheel and it is also driven by the outer gear of the third wheel.

Bifora 910/1: side view of the gear train

side view of the gear train

For cost-saving, a pillar construction was used. It is much simpler in construction, since it uses only a flat base plate, where not much material had to be taken off. The disadvantage is the lower precision, which could result in a lesser precision of the rates.

The Bifora 910/1 uses a golden toned, two-leg anular balance, which is beared in two inhouse Bishock shock protections. It regulates a swiss pallet lever escapement and beats with 18000 A/h, which can be adjusted at the hairspring key only.

Bifora 910/1: lower side of the barrel bridge

lower side of the barrel bridge

The ratchet wheel axle bearing is riveted onto the flat barrel bridge.

Bifora 910/1: the mainspring barrel is open

the mainspring barrel is open

The mainspring barrel is open on one side. Not really nice, but pretty standard for a pillar movement.

Bifora 910/1: calendar mechanism

calendar mechanism

The rather complex calendar mechanism uses a number of springs, which love to fly away.

Very delicate is the switching wheel at position 7 o’clock, whose switching finger is moveable and supported with a spring. It allows a semi-fast correction by turning the hands back and forth.

The Bifora 910/1 has got a yoke winding system, a detail, which is not often to find on a pillar movement, because usually, these movements only use the much simpler rocking bar winding systems.

Bifora 910/1: Bifora 910/1: Dial side

Bifora 910/1: Dial side

Of course, the calendar mechanism is covered. At position 6 o’clock, you see the hole, through with with a prolonged axle, a decentral seconds indication could be realized.

In the lab

This movement came used into the lab and got a very simple service.

Timegrapher result

On this speciman, you can clearly see the need for a real revision after many years of use:

horizontal positions
dial up +13 s/d 211° 0.6ms
dial down 1 s/d 203° 0.1ms
vertical positions
crown right (12 up) -30 s/d 169° 0.3ms
crown up (3 up) -40 s/d 169° 0.1ms
crown left (6 up) -54 s/d 173° 0.8ms
crown down (9 up) -24 s/d 176° 1.0ms

Technical data

Caliber base:Bifora 91
Size:11 1/2''' (measured: 25,54mm)
Number of jewels:17
Escapement:Pallet lever
Balance types: Nickel anular balance (two legs)
Shock protection(s): Bidlingmaier (Bifora)
Balance bearing / direction hairspring:Clockwise
Moveable stud:yes
Adjust mechanism:Hairspring key
  • lever
  • escape wheel, seconds wheel, third wheel, center second pinion
  • center minute wheel
  • mainspring barrel
Construction type:pillar construction
Winding mechanism:yoke winding system
Setting lever spring:3 hole(s)
  • SCI (indirect center seconds)
  • QG (date indication (aperture))
  • RDR (date corrector)
Production period:1962 - 1980
References: Flume: K3 46
Mentioning in literature (years): 1964
Production years:1962-1980
Inventory number:22024

Usage gallery

Bifora 910/1: Bifora gents watch

Bifora gents watch

This movement with watch is a kind donation from Brigitte Abels-Zell to the movement archive. Thank you very much for your kind support!