The Legacy Machine Spit Escapement wristwatch by MB&F may look like any other upmarket mechanical, but something seems to be missing. That's because it's built with an unconventional design that divides the escapement mechanism into two parts set on opposite sides of the watch, making it look as if the timepiece is regulating itself by magic.

Mechanical watches aren't the only precision machines in the world, but they differ from most in that they need to be small enough to be worn or carried in a pocket, and they need to be accurate without the aid of computers or human operators to within a fraction of a second despite the fact they are being constantly moved, turned, jostled, and bumped. Worse, Unlike generators, electric motors, or jet engines, they must do so without the benefit of sitting in a relatively stable environment held in place by concrete foundations or steel frames.

Centuries of development and experience have produced the mechanical watches of today, and one of the key items in making such timepieces possible is the watch escapement. Using a balance wheel, balance spring, escape wheel, and pallet, the escapement turns the energy used to run the watch into a precision means of recording time.

Without the escapement, the watch's mainspring would simply unwind in an instant, but the escapement, combined with a series of gears, slows down the mainspring and rations the released energy in discrete pulses as the balance wheel, regulated by its spring, swings back and forth. To do this, the escape wheel and pallet catch the balance wheel, halt it for an instant, and push it back in the opposite direction, producing the characteristic ticking sound.

Because a watch movement is very susceptible to the various mechanical forces exerted upon it, the usual way to make sure it remains precise and accurate is to keep the parts of the escapement as close together as possible. This is why in skeleton watches or other designs that show off the mechanism, the components that make up the escapements are an easily recognisable set.

In a piece of horological illusion, MB&F's Split Escapement – as designed by watchmaker Stephen McDonnell – stirs things up a bit by taking the parts of the escapement and placing them on opposite sides of the 314-piece, 35-jewel movement. Looking at the face of the watch, the 14-mm balance wheel seems to being doing the impossible as it swings back and forth in perfect time without anything to catch or regulate it. A similar design was used in the MB&F Legacy Machine Perpetual in 2015, but this is the first watch to showcase it.

Splitting up the balance so one side can be seen through the sapphire crystal on the face and the other on the reverse may be attention-grabbing, but MB&F says that it came at the price of some difficult engineering.

For example, the balance arbour needed to hold the components together over a distance of 11.78 mm had to be unusually long. This produces all sort of distortions due to oscillations, torque, and changes in inertia, so this minute axle-like piece had to be redesigned to give it the proper balance and rigidity. In addition, anti-shock jewel bearings were included and the two manually-wound, parallel, spring-barrels needed to provide more power over 72 hours to overcome the greater inertia.

Despite the novelty of the Split Escapement, MB&F wanted to give the watch a classical appearance, so it was given frosted stretched lacquer dials. Since the traditional way of producing such frosting was to use a dangerous nitric acid dipping method, the modern watchmakers opted for using a wire brush to go over the surface in minute sections to create the same effect without chemicals. These were then treated by Physical Vapor Deposition (PVD) to provide a blue, ruthenium, red gold or yellow gold coasting.

The case for the Legacy Machine Split Escapement is made up of 49 components in 18K white gold. It measures 44 × 17.5 mm, is water resistant to 30 m (90 ft, 3 ATM), and includes a push button for adjusting the date quickly. There are sapphire crystals front and back, and the watch is secured by a black or brown hand-stitched alligator strap with white-gold folding buckle.

The Legacy Machine Split Escapement is limited to four editions of 18 units each, available in blue, ruthenium, red gold or yellow gold for US$79,000.

The video below introduces the Legacy Machine Split Escapement.

Source: MB&F

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