Since the days of Galileo and his perpetual motion design, the world has dreamed of overcoming friction with endless kinetic energy. Physicists agree that perpetual motion is a myth, but you can dispel all mythological notions by seeing a watch with a Constant Escapement at Baselworld 2013.

A few years ago Girard-Perregaux announced a constant-force escapement based on a revolutionary concept founded on the elastic properties of a silicium buckled-blade.This component, thinner than a human hair, delivers constant impulses of energy to the oscillator and prevents diminishing torque provided by the barrel’s mainspring from altering the accuracy of the movement.

Just a few watch companies have found ways to achieve constant force using a so-called remontoire d’égalitée, but Girard-Perregaux provides a constant force escapement without a remontoire. We know of only one other watch with a constant force device, not being a remontoire d’égalitée and that is the Tensus by Heritage Watch Manufactory, a watch that we absolutely love here at Monochrome.

However, a few years after the initial launch of the idea, Mike Margolis, Girard-Perregaux U.S. President, told me, “Oh you will see our Constant Escapement in a watch at Basel!” Which watch you ask? Well, mum is the word. Incidentally, the name of the escapement refers to one of GP’s founders, Constant Girard, but the double entendre is intentional.

What is an escapement? An escapement is the heartbeat of the watch and responsible for the ticking that you hear when holding the watch next to your ear. If you have a see-through caseback, you can see the balance wheel of a watch’s escapement oscillating. The escapement parcels out the power from the barrel’s mainspring in precise increments, allowing the hands to move.

In a typical lever escapement (see image left), the energy of the mainspring comes through the gears to the escape wheel, pictured in blue.

All the power would immediately drain from the watch if not for the lever, also pictured in blue, with its pallets (pictured red).

The escape wheel provides impulse to the lever, which transfers that energy to the balance wheel (pictured gold).

The balance wheel spins to its limit, then returns to move the lever; spins the other direction, and returns to move the lever again.

Every time the balance wheel is in its center position, the lever moves allowing the escape wheel to move one click, which also propels the balance wheel in the other direction. At the end of a click, the pallets on the lever arrest the escape wheel until the balance wheel recoils. This common escapement style is a Swiss lever escapement.

There are two problems with a traditional Swiss lever escapement. 1. Decreasing amplitude when the power from the main spring decreases 2. Friction

1. For a mechanical watch, amplitude is the magnitude of change between the balance wheels oscillations. Every mechanical watch is adjusted to 5 or 6 isochronisms, for only one reason, and that reason is to let the watch run as precise as possible. After the watch is adjusted, it has a certain amplitude, and that amplitude changes during the course of unwinding the mainspring. When that happens, the chronometric rate drops, hence the watch no longer runs as precise as it should. The Constant Escapement provides consistent power, meaning a constant amplitude, and constant amplitude equals constant force – problem solved.

2. The other problem is friction. Typically, the lever touches the escape wheel, and its pallets slide against and meet the escape wheel’s teeth. In addition, friction is a problem with the lever contacting the balance wheel. The contact of these working parts requires oil and routine maintenance. Friction decreases accuracy, and the Constant-Force Escapement minimizes friction almost to the point of non-existence. The Constant-Force Escapement defies friction with the key ingredient of silicon for the buckled-blade. It also uses two escape wheels instead of one and a lever that contacts them with ultra-precise indexing, meaning there is increased technological precision in how the lever contacts the wheels. Friction becomes miniscule – another problem solved.