Constant force tourbillon

  • Limited edition
  • Alligator leather strap
  • 46 mm
  • 30 meters water resistance

Trifold approach to chronometry

Its historical roots, aesthetic construction and true-beat seconds ascribe the Arnold & Son Constant Force Tourbillon to the tradition of ultra-accurate marine chronometers.

A constant force involves inserting an energy-storage sub-system into the gear train just before the escapement. Supplied at regular intervals, this secondary reservoir produces extremely regular torque as it is released in consistent, small doses. It therefore differs from the barrels’ energy flow, which is delivered over a long period of time and naturally fluctuates. The balance spring thus receives an invariable source of energy, hence the name Constant Force.

The true-beat seconds is a consequence of this mechanism. As the constant force system is reloaded 60 times per minute, it is possible to display a second that jumps forward from marker to marker by simply attaching a hand to the winding wheel. Despite being a common feature of quartz watches, it remains a rare feat in mechanical timepieces.

Technical Specifications


hours minutes true beat seconds


46 mm 18-carat red gold (5N)


anthracite chapter ring


hand-stitched brown bottier alligator leather

Water resistance

30 meters

Limited edition

28 pieces


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