The Journe Annual Calendar

by Watchbore

November 2002

The styling of F.P. Journe's watches might not appeal to everybody, but few will deny its originality.

The face of the annual-calendar watch shows a fly-back date, the day and the month. The calendar accounts for months of 29, 30 and 31 days. In the non-leap years, when February has 28 days, you have to advance the date manually to March 1.

Journe seems to get away with messing up the face with screws. Note the screw on the lip at 14 on the dates-scale. The dates-hand on the minutes-track of the dial is also unfortunate. But who can deny that this deliberate rejection of perfect harmony gives the watch a very functional character?

The crown controls everything — no pushpieces. You pull it out to its second position, turn it one way to advance all the calendar indications, and the opposite way to advance the days only. In its third position, the crown sets the time.

Most of the cases are in platinum. The face is frosted gold and the dials are silver.

The annual calendar is the third watch based on the F-P. Journe Octa automatic calibre. He called it the Octa because he hoped he would get eight days power-reserve out of it. As it happens, the fully wound movement will run for about 150 hours off the wrist, but there is an unacceptable loss of amplitude after 120 hours.

Despite a long mainspring (1000mm), the Octa construction leaves room for a full-sized free-sprung balance (10.1mm) vibrating 21,600 times an hour on a flat Anachron spring with a microflamed terminal curve. Two opposed pairs of weights on the four-armed balance give up to 100 seconds of adjustment.

The rotor, winding in both directions of spin through a reverser gear, is said to be particularly effective. It needs to turn the arbour 13 revolutions to wind up the mainspring fully. You will note that the rotor is slightly off centre, presumably to allow for indications on the back in a future model.

The Octa's peculiarity is a type of construction unheard of in these days of bolt-on modules. It allows a variety of complications to be inserted in the movement on the same baseplate. Hence the Octa movement with the large date and power-reserve indicator (shown here) has the same dimensions (30mm x 5.7mm) as the Octa chronograph or the annual calendar movements.

The main advantage is economic — one baseplate fits all, and you don't have to make bigger cases for bigger complications. It also results in more compact, less wasteful mechanisms.

The complications have to be configured into a 1mm-high space between the base-plate and the bridges, using holes and recesses common to the other complications. That means Journe cannot use a standard horological design, but has to re-invent each mechanism. These complications have to be as efficient as possible, performing their functions with no mechanical superfluity.

All three Octas demonstrate this mechanical elegance, but the annual calendar is particularly satisfying for its ingenuity and simplicity.

This is how it works in two diagrams:

A great, green wheel (W) with internal teeth drives the annual-calendar mechanism. In particular, it activates that long pink lever (L) every 24 hours so that it reaches across to pull the dates-wheel (D) forward (counter-clockwise) day by day. The dates-wheel with 31 teeth is held by the jumper spring on the left.

On the dates-wheel is fixed a blue snail-cam. As the snail rotates counter-clockwise, a yellow beak (B) rides up on its back, moving the rack (R). The rack turns a pinion on which is mounted the dates-hand. The counter-rack, also engaging the pinion, provides the tension. You can see the blade spring along its right edge.

When the dates-wheel reaches the end of the month, the yellow beak falls off the top of the snail and allows the sprung racks to bring the dates-hand smoothly back to the first of the following month.

Perpetual and annual calendars rely on a cam to tell them how long each month is. The months-cam, which makes an annual revolution, is essentially the program for the year's calendar.

The months-cam (M) is fixed under the 12-pointed months-wheel, which is rotated clockwise by the dates-wheel (D) via a train. The recesses represent months of fewer than 31 days.

The cam acts on the beak in the middle of the pink lever (L). As the beak rises out of a recess at the end of April, June, September and November, it makes the lever advance the dates-wheel twice. The dates-hand thus moves directly from the 30th to the 1st.

You will notice that February has a deeper recess than the other months. When the lever climbs out of the February recess at the end of the 29th day, it advances the dates-wheel and its snail three days. The beak (B) falls off the snail, allowing the sprung racks to bring the dates-hand back to 1.

In leap years, the calendar moves automatically from February 29 to March 1. When February has 28 days, the calendar has to be advanced manually.

The days, on a regular cycle of seven, are clicked forward every 24 hours by the great circumference wheel (Pic 3) through a separate system of levers.

For such a system to work, profiles have to be closely calculated, machined and adjusted to micron tolerances. The correlation between the tiny curve of the snail cam and the wide arc of the dates-hand on the dial has to be exact, as do the profiles of the lever and the months-cam. The toothed racks ensure that the dates-hand points precisely to the intended date and flies back smoothly. The system uses very little power to change the date, which remains isolated from the movement between changes.

The entire mechanism fits into a 1mm-high space within the Octa calibre, using the same baseplate as the movement.