pawls

A pawl is a lever, tooth, or catch used in mechanical systems to engage the teeth of a wheel or rack. By guiding movement in a single direction, pawls provide one-way operation, prevent backsliding, and help control indexing and locking functions. Pawls are commonly found in ratchets, clocks and watches, locking devices, and various inline actuators and gear trains.

In a ratchet mechanism, the pawl cooperates with a toothed wheel so that rotation is allowed forward in discrete steps while backward motion is blocked. The pawl is usually spring-loaded, allowing it to press against the wheel and jump from tooth to tooth as the wheel turns. Some designs use gravity or a toggle linkage instead of a spring.

Variants include single-pawl and multi-pawl arrangements. A single pawl provides simple one-way locking, while several pawls with springs distribute load and increase reliability. In clocks and watches, a similar principle occurs in the escapement, where pallets regulate energy transfer; although not a pawl in the strict sense, the mechanism serves the same directional control purpose.

Pawls are manufactured from hardened steel, stainless steel, brass, or composites depending on load, wear, and environment. They are used in winches, hoists, indexing devices, door and valve locks, automotive assemblies, and other equipment requiring controlled, stepwise movement or secure locking.