Pulsomax® Redux - Ron DeCorte
"Pulsomax® Redux" - Ron DeCorte
Welcome back to Rendezvous. As promised, I will take you on a guided tour of the newest technological development from Patek Philippe: the Pulsomax® escapement. As a refresher, let me bring you up-to-date. Beginning in 2005, Patek Philippe introduced the first in a series of technological innovations from their Advanced Research department: the Ref. 5250 featuring a Silinvar® escape wheel. Again in 2006, another Silinvar® innovation: the Ref. 5350 featuring the Spiromax® hairspring. In 2008, a trilogy of innovations, culminating in the Ref. 5450 featuring a Silinvar® lever, was realized. For the discerning collector, I should I mention that the Ref. 5450 is a limited edition of 300 pieces in platinum. For those who may have missed the previous edition of Rendezvous we invite you to read “Pulsomax®, Ref. 5450” first, this may shed a bit more light on the subject we are about to explore.
It is a trilogy of innovations that brought Patek Philippe to the completion of their evolutionary Pulsomax® escapement. In order to begin the evolution I will start you off with an animation of a typical Swiss escapement. In the middle of the screen is a lever, or anchor, that is moving left to right and limited in each direction by mechanical banking stops. At the top is a "D" shaped rotating ruby jewel that engages a finely tuned slot in the lever several times per second (don’t be misconceived by the animation, it has been slowed dramatically for visual purposes). You will also notice the two ruby pallet stones inserted into the lever that dispense a small amount of energy to the lever, via the escape wheel at the bottom of the screen, each time it moves from left to right. This small, but very important, transfer of energy is what keeps a mechanical watch ticking. I should point out that the components of a typical Swiss lever escapement are made of steel with a few rubies inserted.
Traditional Swiss lever escapement
Pulsomax escapement
Now the Pulsomax® escapement. Most notable is the dramatic change in the geometric shape of the lever as compared to the typical Swiss lever. But more importantly is the fact that it is made of Silinvar®, a highbred component of Silica that has 1/3 the mass of steel. The escape wheel that provides the impulse to the lever and thus to the balance wheel, or oscillator that we will discuss a bit later, is also made of Silinvar®. The combination of Silinvar® to Silinvar® has very low friction and eliminates the need for oil. What does this mean and how does it improve my watch? First we should remember that when oil gets a bit old it becomes sticky and mucky, requiring someone to clean and re-oil. And secondly, when there is less friction the components wear less. Sounds simple, so why isn’t every watch equipped with a Pulsomax® escapement?
Deep Reactive Ion Etching (DRIE) is the manufacturing method that makes super precision Silinvar® components possible, with each component being completely made as a singular component compared to the typical Swiss lever that is a composite of steel and ruby parts requiring numerous adjustments to operate correctly. Looking closely at these two photos you will see that the escape wheel is held via notches formed in the lever pallets, eliminating the need for mechanical banking stops as required in the typical Swiss lever escapement. Although these photos where made using a large scale Pulsomax® model, the DRIE process is the only manufacturing method capable of forming watch sized Silinvar® components to the required accuracy, up to 10 times more accurate than conventional machining methods.
Left and right notches in the lever pallets (Pictures made using a large scale Pulsomax® model)
Conventional hairspring
So far we’ve examined two of the Pulsomax® components: the lever and escape wheel. But Pulsomax® is a trilogy consisting of three Silinvar® components and it is time to examine the hairspring. Here we can see a conventional steel hairspring as it breaths while being wound and unwound via the small energy impulses provided by the escape wheel and transferred via the lever to the balance wheel. Look closely and you will see that the coils of the hairspring are not breathing in a concentric manner. In other words, the coils gather up in a rather unsymmetrical pattern, wasting energy and causing undue friction upon the balance wheel.
In this example we can see the Spiromax® hairspring in action, in very slow motion video. Notice how much more concentric the coils of the hairspring wind and unwind in a very symmetrical manner. This symmetry is made possible via a Patek Philippe patented terminal curve (outer coil) of the spring that could only be produced using Silinvar® and the DRIE manufacturing process. The Spiromax® hairspring plays a very important role in the trilogy of Pulsomax®.
Spiromax® hairspring
Picture made using a large scale Pulsomax® model
Let me say that there are a multitude of advancements in the Pulsomax® escapement that would require a book, and a high level of watchmaking knowledge to understand completely, including the newly designed pallet geometry that has greatly improved the efficiency of the entire escapement. There are nay-sayers that discount the idea of bringing innovations into the world of watchmaking, I disagree. Until recently, there was a 50+ year vacuum of new and innovative ideas in the world of mechanical watches and this might explain the resistance to the introduction of new ideas and technology. But rest assured there are watch manufacturers that have the vision, stamina, and resources to bring mechanical watches to a whole new level in the 21st century. The Pulsomax® and Spiromax® are proof of these intentions.
In conclusion, let me point out some of the major advantages of the Pulsomax® escapement and Spiromax® hairspring:

As a trilogy of Silinvar® components working together they afford a much greater degree of accuracy, both in terms of mechanical accuracy and precision time keeping.

Silinvar® being of Silica is totally anti-magnetic and is thus immune to magnetic influence, a major disturbance of precision time keeping.

The manufacturing method Deep Reactive Ion Etching (DRIE) brings the most accurate components and complex geometric shapes to reality, eliminating the need for hard banking pins that cause undue shock to the mechanics.

DRIE also enables the ultra-precision manufacture of the lever pallets, that interact with the escape wheel, affording a much greater degree of efficiency to the watch. This results in longer running time and a more stable rate of accuracy.

Pulsomax® being of Silinvar® materials exhibits great anti-friction properties and requires no oil, lengthening the time intervals between servicing.

Thank you for visiting Rendezvous at Please continue to the next page to give us your comments as they are important in our pursuit of excellence.
The Trilogy