The five phases of the Swiss lever escapement
Click a phase to repeat that section in slow motion; switch off “Loop” to stop repeating it. Focus the view on the pallet, fork or balance. Drag to rotate, and use the mouse wheel or two fingers to zoom.
With Pallet focus, dimension lines show total or drop lock as a bar on the locking face, and both impulse faces as lines. Impulse is colour-coded into Pallet impulse and Tooth impulse, including on the balance scale. Clockwise angles are positive.
In slow motion, each impact sounds separately when the animation reaches it. Click an impact to hear it and see its position. The diagram combines drop and banking impact into one sound; in the rigid model they are separated by 5.25° or 5.65° of balance angle. At normal speed (18,000 vibrations per hour), the three sound packets span about 8 ms.
Continuous sequence of all phases
Swiss lever escapement with a 15-tooth club-tooth escape wheel, adjusted to the workshop rule: drop lock ⅛ and locking depth ¼ of the impulse-face length. Motion is calculated from this model’s actual shapes: the parts make contact, while inertia is neglected. In reality drop lasts only fractions of a millisecond; it is greatly stretched here.