Introducing the Patek Philippe ref. 5470P 1/10th Second Monopusher Chronograph

Following Watches and Wonders, Patek Philippe has dropped an unexpected technical bombshell – the ref. 5470P – its first-ever 1/10th second single-pusher chronograph that measures and displays 1/10th of a second with a new 5Hz movement.

Importantly, not only is the new reference a high-frequency chronograph with a resolution of 1/10th of a second, it is also a high-performance chronograph that is packed with solutions to address the shortcomings inherent in a horizontally coupled mechanism and is further bolstered by the full suite of Patek Philippe’s Advanced Research department most cutting-edge innovations.

CH 29-535 PS 1/10 Movement

Boasting seven new patents, the CH 29-535 PS 1/10 movement is constructed based on the existing 4Hz CH 29-535 PS launched in 2009. It is characterized by highly traditional architecture – manually wound, column-wheel control, horizontally coupled. Most notably, the calibre CH 29-535 PS features an instantaneously jumping minute counter thanks to a patented perforated minute cam with a slot at the end, a skeletonized lever and a coiled spring to advance the minute counter instantaneously.

However, to achieve a precision of 1/10th second, greater torque was required to increase balance power. But rather than installing a second barrel or doubling its thickness, both of which increase the size of the movement, Patek instead reduced the diameter of the barrel arbor, thereby increasing the coils of the mainspring. Further, a patented notch was added to the arbor to reduce the tension exerted by the spring hook while the mainspring is being wound.

Secondly, with an increased frequency, the efficiency of energy transmission in the escapement would, in turn, decline. To avoid this, the entire oscillator was replaced by an escape wheel, lever (Pulsomax), balance wheel (GyromaxSi) and hairspring (Spiromax) made of Silinvar, known collectively as the Oscillomax. Silinvar is essentially silicon that has been coated with silicon dioxide, making it resilient to temperature changes on top of the material’s inherent benefits, including low density and a perfect surface state, allowing it to operate with little energy and without lubrication. At its core, the Oscilllomax was designed to operate with low inertia and is produced using a deep reactive-ion etching (DRIE), resulting in its skeletonized geometries that are lighter to ensure the quickest acceleration of parts.

The CH 29-535 PS 1/10 movement comprises of two separate chronograph mechanisms so as to display both the seconds and stopped tenths of a second. As such, a 1/10th second mechanism was added to the existing chronograph mechanism. As a recap, in a standard horizontally coupled chronograph mechanism, a wheel that is mounted on the pivot of the fourth wheel drives an intermediate clutch wheel. When the chronograph is engaged, an intermediate lever shifts the clutch wheel horizontally until it meshes with the chronograph seconds wheel, causing the seconds counter to start ticking. In the CH 29-535 PS 1/10 movement, it is the drive wheel on the original chronograph that powers the 1/10th second mechanism. In other words, both chronograph mechanisms are driven off the fourth wheel.

Given the inherent disadvantages of a horizontal clutch mechanism, particularly the sudden, imperfect mating of the clutch wheel and chronograph seconds wheel, the potential pitfall of such a construction is twofold as more wheels naturally mean more inertia and backlash. To avoid this, Patek designed a special driving wheel for the 1/10th second mechanism that is made up of two stacked gears – a lower wheel with conventional spokes and an upper wheel with flexible spokes. The latter is made possible with the use of a micro-electro-mechanical system known as LIGA (the German acronym for Lithographie, Galvanoformung, Abformung) – a process that allows for extremely precise fabrication. The flexible wheel is offset from the conventional wheel. As the latter rotates, the flexibility of the LIGA wheel enables it to compensate when the lower wheel slips, thereby removing play and preventing the 1/10th second hand from jittering.

As with a traditional chronograph, this drive wheel is in constant contact with a clutch wheel, which is characterized by serpentine spokes. When the chronograph is activated, the clutch wheel pivots to engage a pinion in the middle. With a diameter of just 1.469 mm, this pinion was micro-toothed with 136 teeth, making one revolution in 12 seconds.

Additionally, Patek Philippe developed two patented mechanisms to ensure a smooth and constant engagement in the event of a shock. The first is a shock absorber hook that would secure the clutch lever in its position as the chronograph runs. It engages with hooks on a shock absorber cap over the column wheel. The second is a “Pendulum” shock absorber lever with an integrated pre-tensioning spring. The latter was designed with a strategic center of gravity so that it shifts the clutch wheel horizontally until it meshes with the pinion regardless the direction of shock.

A Patented Concentric Display

The Calibre CH 29-535 PS 1/10 is housed in a Calatrava case made of platinum, as denoted by a diamond set into the case band at six o’clock. It measures 41 mm wide but, remarkably, just 13.68 mm high. It is paired with a blue lacquered dial that displays both the chronograph seconds and 1/10th seconds concentrically, with an outer 12-sector railway track scale subdivided into tenths.

The chronograph elapsed seconds is indicated by a rhodium steel hand, while the 1/10th seconds is indicated by a lacquered red hand made of Silinvar to reduce inertia. Nominal as it may seem, the process of coating a Silinvar hand with lacquer accounts for two patents. The first is a primer coating that improves the adhesion of lacquer on a silicon oxide surface, which consequently necessitates a special process, the subject of a second patent, for joining the lacquered hand to the brass pipe of the hand. Advancing five times faster than the elapsed seconds hand, the 1/10th seconds can be read easily by the number of elapsed tenths of a second departing from the last red marker.

The Patek Philippe 5470P-001 1/10th Second Monopusher Chronograph is a permanent reference in the collection and is priced at CHF 380,000.

Tech Specs

Ref. 5470P-001 1/10 th Second Monopusher Chronograph

Movement: Caliber CH 29-535 PS 1/10
Power Reserve: 48 hours
Frequency: 36,000 VPH (5Hz)
Functions: Manually wound mechanical movement, chronograph with columnwheel control, horizontal dual clutch with wheels and instantaneous 30-minute counter, module for tenths-of-a-second measurements of the chronograph with sweep hand, small seconds
Case: 41mm diameter; 13.68 mm; platinum
Dial: Brass, lacquered blue Applied Breguet numerals in 18K white gold and minute pearl markers Railway track scale printed white and red (minutes, snailed small seconds at 9 o’clock, snailed 30-minute chronograph counter at 3 o’clock)
Strap: Calfskin with embossed fabric pattern, hand-stitched, navy blue with red contrast seams, fold-over clasp in 950 platinum
Price: CHF 380,000
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