What type of mechanism did Leonardo da Vinci design to stop a rotating shaft from turning backward?

Leonardo da Vinci designed ratchet mechanisms to prevent a rotating shaft from turning backward.

A ratchet uses a toothed wheel and a pawl that permits motion in one direction while blocking reverse motion. Leonardo included this principle in mechanical drawings, applying it to devices that required controlled winding, lifting, or rotation.

The ratchet principle was known before Leonardo, so he was not its original inventor. His importance lies in documenting and developing mechanical applications during the Renaissance, when engineers were studying how gears, springs, weights, and shafts could work together.

Ratchets appear in many later tools and machines, including winches, clocks, jacks, and bicycle mechanisms. A ratchet is different from a flywheel: a flywheel stores rotational energy, while a ratchet controls the permitted direction of movement.