Lever escapement

Inline or Swiss lever escapement (blue) and balance wheel (yellow)
Animation of inline lever escapement, showing motion of the lever (blue), pallets (red), and escape wheel (yellow)
A lever escapement in a mechanical watch. The largest brass circle is the balance wheel. The escape wheel is the silver gear above and to the right of it whose bearing is surrounded by decorative engraving. Most of the lever itself is hidden, but both pallets are visible.

The lever escapement, invented by the English clockmaker Thomas Mudge in 1754 (albeit first used in 1769), is a type of escapement that is used in almost all mechanical watches, as well as small mechanical non-pendulum clocks, alarm clocks, and kitchen timers.

An escapement is a mechanical linkage that delivers impulses to the timepiece's balance wheel, keeping it oscillating back and forth, and with each swing of the balance wheel allows the timepiece's gear train to advance a fixed amount, thus moving the hands forward at a steady rate. The escapement is what makes the "ticking" sound in mechanical watches and clocks.