August 21, J.F. and 2020 (n.d.). In-Depth: The Modern Watch Escapement, And How It Got That Way. [online] HODINKEE. Available at: https://www.hodinkee.com/articles/the-modern-watch-escapement-and-how-it-got-that-way.

• Every mechanical watch has a mainspring that drives the motion of the wheels

  • This replaces the heavy weight in wight-driven clocks

  • The mainspring barrel is made to rotate as the spring inside uncoils

• The wheels connect, transferring energy, and eventually reach the escape wheel that drives the balance

• The balance is what keeps the escapement in time

  • It acts like a pendulum

    • The balance spins one way and, at a point, the balance spring inside pulls it back and it spins the other way. The cycle then repeats, just like a pendulum oscillating

      • The force of the balance spring pulling the balance back is the same as the force of gravity on a pendulum

    • The balance will eventually stop spinning, due to friction, so the escapement mechanism provides an impulse to give it energy to continue

• Originally the anchor escapement was used but it was not ideal

  • For an ideal escapement:

    • Impulse should be applied only when the balance is at the equilibrium point, in both directions and with equal force

    • No friction, as it dissipates energy

    • No oil, as it eventually thickens and evaporates

    • It should be self-starting: it will automatically start once energy is wound into the mainspring

    • It should have good safety and not unlock accidentally

    • Should interfere with the oscillator, the balance, as little as possible

  • The anchor escapement fails at the first 3

• Lever escapement

  • 2 palettes that make contact with the escape wheel, similar to the anchor escapement, are attached to a lever arm that then makes contact with the balance, at the equilibrium point, to push it along

  • In almost all mechanical watches today

  • Better than anchor

    • Delivers impulse in both directions

    • Difficult to knock, so has good safety, because of pins on either side of the lever

      • Also stops the lever from moving any further at either extreme of its swing

  • Still a problem of friction: the teeth of the escape wheel still very frequently scrape across the ruby palettes

  • The Chronergy escapement, developed by Rolex, is a lever escapement with modifications

    • Smaller palettes

    • Skeletonised escape wheel

    • The lever is slightly off-centred

    • All of the above reduces friction, but its still not perfect

• Detent escapement

  • The escape wheel directly interacts with the balance, by hitting a palette on the balance, and is stopped from continuously rotating by then making contact with a locking palette. The locking palette then lowers once the balance does a full oscillation, releasing the escape wheel and repeating the process

  • Used on boats

    • Cannot be used in wristwatches as it cannot be tipped all over the place

  • Doesn’t use oil and has no sliding friction

    • Because there is no lever and the escape wheel directly interacts with the balance

• Co-axial escapement

  • Combination of lever escapement and detent escapement

  • Uses 2 escape wheels that work together to create a system that gets the lever to indirectly provide impulse to the balance

  • New and rare

    • Very expensive