Reference 5204R-011Split-Seconds Chronograph And Perpetual Calendar

So it might be simply a dial color change but the overall effect is one that creates an altogether sportier and more vibrantly youthful version of Patek Philippe’s venerable perpetual calendar with Split Seconds chronograph the Reference 5204.

And it must be said that Patek’s use of color in its dials, expressed by the ref. 5236P In-Line Perpetual Calendar’s stunning graduated blue, the end-of-series ref. 5711 olive green and now this timepiece’s ravishing slate grey sunray. As I have a clear obsession with Patek Philippe perpetual calendar chronographs, which compelled me to write this historical retrospective I’ve always considered these watches to be emblematic of the very best in complicated watchmaking.

But when the 5004 was launched in 1994, Patek elevated this complication to realms of horological Valhalla, with the addition of a split seconds chronograph, or rattrapante. The only issue was that the base caliber of this watch, the venerable Lemania 2310 designed by Albert Gustave Pellaton and industrialized in the 40’s, was that it was never intended to be a split seconds chronograph. As explained to me by the amazing Philippe Stern, this necessitated a great deal of innovation to reverse engineer a solution to “rattrapante drag” where the amplitude of the watch would drop each time the split second brake was deployed.

Read more: Complete Guide: Patek Philippe’s Modern Chronographs

This resulted in an isolator mechanism that is nicknamed the “Octopus” by Patek devotees. But when it came time to replace the Lemania based CH 27-70 Thierry Stern was determined to create a movement, the CH 29-535 that was from the ground up optimized to be the perfect base for a rattrapante.

Launched in 2012, the 5204 perpetual calendar chronograph is replete with some very serious functional improvements to the 5004. The first is as described earlier: to overcome rattrapante drag, Patek had to create their now legendary Octopus isolator mechanism. Now it is important to understand that at the time of the 5004’s launch the Octopus was ground-breaking technology.

There are two mainsprings in this isolator system. The first is the spring for the split seconds brake which allows its clamping function. The second is the isolator wheel spring that sits on top of the split seconds wheel and necessitates a good bit of extra height. Now this is the important part. The springs of the isolator wheel and the springs of the split seconds brake act in opposite directions. That’s because the Octopus rotates in just one direction. When the clamp of the split seconds brake opens, the Octopus wheel has to rotate to its home position, which is done by the isolator wheel spring.

Which means that it has to overcome the force of the split seconds brake spring. So when approaching the isolator mechanism of the new 5204, Patek went back to the drawing board. And the first thing they did was get rid of the isolator wheel spring mounted on the split seconds wheel. Instead they ingeniously integrated this spring as part of the split seconds column wheel cap. The second thing they did was design an isolator that can move back and forth in two directions and thus doesn’t have to overcome the force of the brake spring which is much better for long term reliability.

Six Patents for the CH 29-535 PS

The first patent relates to an all-new tooth profile for both the central chronograph wheel and the drive wheel. In previous movements, these wheels meshed in such a way that the teeth might not mate precisely, which caused chronograph backlash or the seconds hand to jump forward or backward in an unsightly way. Patek eliminated that with its all-new profile, which allows the teeth to slip easily into place even if they contact point to point.

The second patent relates to the synchronization of the brake and clutch lever. Basically the brake lever needs to be disengaged precisely at the moment the clutch engages and the drive wheel contacts the chronograph seconds wheel. And it needs to be back on as soon as it disengages from the chronograph wheel. Previously, these two levers were operated by the column wheel and had to be adjusted individually, so getting the timing right was extremely labor-intensive and challenging. In the CH 29, the brake lever is operated by the arm of the clutch lever. An eccentric screw on the clutch lever allows Patek’s watchmakers to adjust the depth of engagement and the timing to perfection.

The third patent relates to the eccentric cap on the column wheel. OK, so to meet Geneva Seal requirements, your column wheel needs to wear a decorative cap. But leave it to Patek Philippe’s engineers to transform this into an eccentric element that actually controls the depth to which the drive wheel and the chronograph wheel mesh. This is absolute genius as it takes what was previously a purely decorative element and gives it a vital function. Bravo, Patek!

The fourth patent relates to the system for the precise jumping minute counter. The first watch to feature this type of chrono counter was the Lange Datograph. However, this watch uses a system with a snail cam on the chronograph wheel and a feeler that drops off the end of the cam each time the seconds hand passes the one-minute mark and drags the minute counter forward. Patek came up with a system with a pierced cam and a much gentler slope. In addition, the pressure on the feeler is provided by an oversized coiled spring, much like a hairspring, that allows the minute counter arm to accomplish all its functions while creating less friction by reducing the level of spring tension needed to achieve them.

The fifth patent has to do with self-adjusting hammers. On the Lemania 2310, the reset hammers for the minute counter and the chronograph seconds wheel are one piece. Getting them to strike their respective heart cams at the same time is challenging. In the CH 29, the minute reset hammer is individually sprung and pivots on the seconds hammer. Again, why no one had thought about this before is incredible, but leave it to Patek to achieve it.

Patent six is that these reset hammers are pivoted between jewels to eliminate friction and bring an ever-greater aura of horological finery to this amazing movement.

The first model on the 5204’s maiden launch was a platinum case beauty with a silvered solid gold dial and luminous hands and indexes. To me this was a wink to the special order luminous 5004 watches owned by collectors such as John Mayer and Mike Ovitz. The dial of the 5204 is also distinguished by a moonphase indicator that opens across the lower half of the 6 o’clock subdial. In 2017, Patek introduced a rose gold version also with luminous hands and indexes. Patek’s current catalogue shows three versions of the watch: a platinum watch with black dial, the rose gold watch with white dial and an incredible rose gold watch with black dial on a 5-link grains-of-rice/bead bracelet. But this year the extraordinary 5204 gets a rose gold version with a spectacular slate grey sunray dial, which I have to say I feel is one of the prettiest Patek complicated chronographs of all time. What could make it better? The option of have it on a 5 row Beads of Rice bracelet. On the subject of bracelets the grey strap that is supplied is in fact an embossed calfskin strap as opposed to alligator and I applaud Patek’s decision to shift away from exotic skin straps.

Tech Specs

Dial: Slate gray sunburst, gold applied hour markers with luminescent coating; 18K gold dial plate; rose gold faceted dauphine hands with luminescent coating

Case: Rose gold; diameter: 40 mm; height: 14.3 mm; water-resistant to 30 m; interchangeable solid and sapphire crystal case backs

Strap: Calfskin, embossed alligator pattern hand-stitched, shiny gray; fold-over clasp

Movement: Caliber CHR 29-535 PS Q; manual winding; split-seconds chronograph; instantaneous 30-minute counter; perpetual calendar; day, month, leap year and day/night indication displayed in apertures; date indicated by hand; moon phases; small seconds; diameter: 32 mm; height: 8.7 mm; number of parts: 496; frequency: 28,800 semi-oscillations/hour(4 Hz); balance: Gyromax®; balance spring: Breguet; power reserve with the chronograph disengaged: min. 55 hours – max. 65 hours

More information: patek.com