Girard Perregaux

AndrewD
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Baselworld 2013: Girard-Perregaux Constant Escapement

This is the first Girard-Perregaux mega-watch of 2013 and a piece that has been rumored for several years. Some of you will have seen the evolution of the prototype movements if you visited the secret GP Research and Development Laboratory in La Chaux-de-Fonds. It has been a 5 year journey but the final cased up watch is finally being launched at Baselworld this week.

It is not often in the long history of watchmaking that we get to experience a totally new escapement architecture and a rethink on the problems of delivering constant force. The principle of a constant force escapement is that whatever energy is supplied by the main spring barrel, the escapement returns a constant energy to the regulator (the balance wheel).

In the new GP Constant Force escapement an intermediate device, consisting of an extremely thin silicon blade (it measures 14 micrometers – one sixth of a human hair’s thickness), is integrated into the escapement. This blade stores energy and then transmits it all, instantaneously, to the balance before commencing another cycle. This blade is flexed to a point as close as possible to its unstable state, and only needs an infinitesimal quantity of energy, a micro-impulse given by the balance wheel – less perturbing than in a lever escapement – for it to snap from one state to the other, and in the process, to push the balance wheel forward, compensating for the variable energy of the barrel and liberating the same quantity of energy every time. This force is instantaneous and continuous.

While the escapement design is beautifully symmetrical, this is a case of form follows function – the forces at the center of the balance wheel are indeed balanced and therefore avoid a concentration of constraints at that point in order to ensure totally unencumbered rotation.

The blade is formed in one piece with the frame which holds it by both ends and plays a role in the very precise locking of the point of contact for the micro-impulse which will make it snap over. The micro-engineering required to build such an escapement is impressive and requires modern materials such as silicon and manufacturing techniques such as deep reactive ion etching (DRIE). This has been achieved via a partnership with CSEM (the Swiss Center for Electronics and Microtechnology) in Neuchâtel, Switzerland. The whole escapement is modular and can be replaced making service easier.

There is no friction in the blade except at the moment of the impulse and the flexing of the blade. The natural vibration of the blade governs the frequency: 3 Hz or 21,600 vibrations per hour. The two novel escape wheels have three teeth for a frequency of 3 Hz, but other frequencies could be used by increasing the number of teeth (four would be required for a 4 Hz escapement).

The movement runs for a week and the power reserve is shown in a linear power reserve indicator. The energy is supplied by twin barrels coupled in parallel and each drum contains two springs stacked in series. The total length of the springs is 3 meters!

Despite all this modern jiggery-pokery, the movement blanks are in brass coated in black PVD and there are references to GP design icons such as the three bridges supporting the movement on the dial side and two arrow bridges on the rear. In fact the view of the rear is as inspiring as the front and all is on display under non-reflective sapphire.

This first model in the Constant Escapement L.M. collection has been designed to be modern and imposing and to fully demonstrate the engineering tour de force it carries. The case is in white gold and measures 48mm x 14.63mm. The hours and minutes are displayed on a sub-dial at 12 o’clock, flanked by the double barrels.

Barrel

Clickwheel

Escape wheel

Spherical differential

Technical Specifications

Case: white gold

Diameter: 48.00 mm

Glass: domed anti-reflective sapphire

Crown: white gold with engraved GP logo

Dial: silvered with grained finish and rhodium-plated appliques

Hands: dauphine style

Case back: sapphire glass, secured with 6 screws, all inscriptions hand engraved

Water resistance: 30 meters

Girard-Perregaux Movement MVT-009100-0007

Hand wound mechanical movement

Caliber: 17½ ’’’

Frequency: 21,600 Vib/h – (3 Hz)

Power reserve: approximately one week

Jewels: 28

Number of components: 271

Functions: hour, minute, central second, linear power reserve

Black alligator strap

White gold folding clasp