Automatic Hammer with a Self-Releasing Escapement
A framed striking machine that disengages its driving wheel after the final blow
The sheet is dominated by a large machine set within a timber frame, worked by pulleys, hanging counterweights, gear wheels and a triangular tensioning arrangement. Leonardo's note explains an escapement: when the hammer delivers its last blow it trips a counterweight that pulls a pinion clear of the driving wheel, so an extra stroke cannot spoil the work. A star-shaped drum bristling with mallet-arms is drawn at the upper left, and clamps, presses and a spring are studied at the lower left; the catalogue also files crossbow components with this sheet.
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Escapement that halts the hammer after its last blow
The device is arranged so that when the hammer strikes its final blow it touches a trigger that lets a counterweight fall, and that weight draws the pinion clear of the teeth of the wheel of the first motion. This prevents a surplus stroke from ruining the work and keeps the driving wheel from wasting time on the blows that remain.
Spring among the component studies
A label numbered 3 marks a spring (molla) among the small mechanical studies gathered at the lower left of the sheet.
Counterweights and pulley train in the frame
Within the tall timber frame, cords run over pulleys to pear-shaped hanging weights, and a triangular linkage transmits their pull to the striking bar. The arrangement stores and releases force to drive the repeated blows of the hammer.
Star-shaped multi-mallet drum
At the upper left a rotating cylinder carries several mallet-arms projecting radially like a star, suspended so that it can turn and strike in sequence.