Caliber 29-535 PS

Caliber 29-535 PS

A Mechanical Marvel

With its caliber CH 29-535 PS, Patek Philippe has yet again redefined the benchmark in chronograph architecture. Over a period of five years, the new manually wound chronograph movement was developed entirely in-house on the basis of traditional principles. But at the same time, it embodies a number of patented innovations and technical refinements that improve the functionality and dependability of the chronograph. As a shining example of the pursuit of excellence for which Patek Philippe is known, it also epitomizes technical perfection and the pinnacle of micro-mechanical craftsmanship

Pure Performance

The CH 29-535 PS is a movement based on the principle of the column wheel, no doubt the defining hallmark of the most beautiful mechanical chronographs. Needless to say, Patek Philippe’s column wheel is crowned with a polished cap. The watch has a large chronograph hand, a seconds sub-dial, and an instantaneously jumping 30-minute counter. Its large four-spoke Gyromax balance wheel with four poising weights beats at a frequency of 4 Hz (28,800 semi-oscillations/hour). The caliber has a guaranteed power reserve of 65 hours (58 hours when the chronograph is activated). The clutch lever exhibits the classic “S” shape. The remarkably aesthetic design vocabulary also extends to the two characteristic bridges in these types of watches, the chronograph wheel bridge and the minute-counter bridge. The movement also has a stop-seconds feature that makes it very convenient to accurately synchronize the watch with an official time signal when the crown is pulled.

A Perfect Reflection of the Patek Philippe Seal

Down to the very last detail, the new CH 29-535 PS is a perfect example of what compliance with the criteria of the Patek Philippe Seal means. In the development phase, its engineers focused on exemplary user convenience, giving top priority to functionality and long-term reliability. The idea behind the ingenious shapes and configuration of the bridges is to minimize friction and maximize energy transmission efficiency from the mainspring barrel to the escapement in the interest of amplitude stability and rate accuracy. The engineers spared no effort to minimize the size of the highly complex movement, which has a height of only 5.35 millimeters and a diameter of 29.6 millimeters. In the course of the development process, every movement part was submitted to the Comité de surveillance (Supervisory Authority) of the Patek Philippe Seal to make sure all components comply with the manufacture’s extremely strict technical and aesthetic specifications.

The Quest for Aesthetic Grace

As befits Patek Philippe’s tradition, the CH 29-535 PS presents itself as a new point of reference for aesthetic appeal and artisanal workmanship. Its salient features include captivatingly elegant components and old-style bridges that are meticulously chamfered, polished, and decorated with Geneva striping. Every surface, no matter how small, is beautifully finished in numerous consecutive steps, most of them manually executed. And in compliance with the criteria of the Patek Philippe Seal, none of the movement embellishments interfere in any way with the caliber’s functional integrity.

The Heritage of Innovation

The CH 29-535 PS movement is based on the classic architecture of column-wheel control and a geared clutch system. However, it is a brilliant masterpiece that unites six patented innovations – each one is a manifestation of the workshops’ inventive spirit. The caliber engineers examined all of the essential components of the chronograph mechanism and embarked on the quest for new solutions that would improve precision, reliability, longevity, and convenience. Their focus always remained on functionality and user-friendliness as stipulated by the principles of horological artistry and by the Patek Philippe Seal.


The development of the CH 29-535 PS movement culminated in six patents and patent applications that represent the latest advances in chronograph technology


The engineers provided separate bilateral jeweled bearings for both the seconds and minutes hammers on the same axis. Each hammer is pressed against its respective heart cam with its own spring. This system assures that the hammers remain precisely aligned in the vertical direction and improves the smoothness of their rotation.


The adjustment between the teeth of the clutch wheel and the teeth of the chronograph wheel is performed by a large eccentric column wheel cap, working directly with the tip of the clutch lever instead of the conventional eccentric placed next to the clutch wheel. This new system enables a more precise adjustment of the penetration between the clutch and the chronograph wheel.


Ordinarily, the clutch lever and the blocking-lever are synchronized by the column wheel. The engineers of the CH 29-535 PS eliminated this intermediate step by fitting the clutch lever with a finger piece that directly synchronizes both the clutch lever and the blocking-lever. This solution simplifies and improves the precision adjustment of the control sequences because the watchmaker only has to adjust one point instead of two as was the case in the past. Moreover, this approach suppresses the jump of the chronograph hand when time measurements are started and stopped.


The reset hammers of the chronograph counter are equipped with a self-setting system that makes it unnecessary to mechanically adjust the minute hammer function and thus increases the reliability of the mechanism.


The wheels of the chronograph mechanism feature an exclusive patented tooth profile (presented for the first time in 2005 when the ultra-thin caliber CHR 27-525 PS split-seconds chronograph was launched). It eliminates the risk of hand jump in both directions when starting a measurement ; limits the quivering motion of the chronograph hand ; increases energy transmission efficiency, and reduces friction as well as wear in the movement.


A new minute-counter cam was created with a slot to prevent abrupt blocking in response to the reset command and therefore eliminates hand quivering.