Pawl

For other uses, see Pawl (disambiguation).

A pawl is a movable lever that engages a fixed component to either prevent movement in one direction or restrain it altogether. As such, it is a type of latch and can also be considered a type of dog. It typically consists of a spring-loaded lever that engages a mating component at a steep enough angle to restrain it. Pawls are often tapered, being widened at their pivot for anchoring and narrow at their tip.

A ratchet and pawl mechanism

A parking pawl in an automatic transmission

Applications

Anchor windlass

A pawl is used in an anchor windlass to prevent a free-spooling chain by grabbing and snubbing an individual link. Similar mechanisms include a Devil's claw, or a claw and dog.

Ratchet

A pawl is used in combination with a ratchet gear in socket wrenches, bicycle freehubs, winches, ratchet reels for diving, fishing, and many other applications.^[1][2]

Ladder

Dogs (in the form of pawls) are used on extension ladders to temporarily anchor their sections to one-another.^[3]

Table saw

Pawls are used on table saws to prevent a workpiece being sawn from kicking back.^[4]

Transmission

A parking pawl is a device in an automobile automatic transmission which prevents it from moving when the vehicle is parked .^[5]

Revolvers

The hand (pawl) indexes the cylinder.

References

1. Nitaigour Premcahnd Mahalik, Mechatronics: Principles, Concepts and Applications, p. 271, Tata McGraw-Hill Education, 2003 ISBN 0070483744.
2. Richard Krolak, Cruising World, "Servicing your winches", April 1990, pp. 107-108
3. International Association of Fire Chiefs, Fundamentals of Fire Fighter Skills, p. 363, Jones & Bartlett Publishers, 2012 ISBN 1449666507.
4. Table Saw Techniques: Use Your Saw Like a Pro, p. 12, Quarto Publishing Group USA, 2003 ISBN 1610602951.
5. Keith Santini, Kirk Vangelder, Automotive Automatic Transmissions and Transaxles, p. 174, Jones & Bartlett Learning, 2017 ISBN 1284122034.