Pawl

Pawl

A pawl is a lever arm that rests against a toothed ratchet wheel in a basic ratchet mechanism, designed to allow the wheel to rotate in only one direction. It can be used as a holding pawl to prevent the ratchet from rotating backward during the idle stroke, and is typically pressed against the ratchet teeth by a spring to keep it engaged with the wheel.From: Design and Testing of Ratcheting, Tension-Only Devices for Seismic Energy Dissipation Systems [2020], Mechanics of Machinery [2019], Power Mechanisms of Rotational and Cyclic Motions [2019]

Hydraulic brake systems

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Purchase Book

Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007

M.J. Nunney

This takes the form of either a pivoted or a sliding handbrake lever incorporating a pawl and ratchet mechanism. As the lever is pulled towards its on position, the spring-loaded pawl slides over the stationary ratchet teeth. When the handbrake is fully applied and the driver releases hold on the lever, the pawl transmits a locking force to the ratchet teeth owing to their special form and thus prevents the lever from returning to the off position. To return the handbrake to its off position, pressure on a release button or catch overcomes the spring load on the pawl to disengage it from the ratchet.

Design and Testing of Ratcheting, Tension-Only Devices for Seismic Energy Dissipation Systems

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Journal Information

Published in Journal of Earthquake Engineering, 2020

Jarrod Cook, Geoffrey W. Rodgers, Gregory A. MacRae

In a basic ratchet mechanism, a lever arm, known as a pawl, rests against a toothed ratchet wheel, where the tooth profile is designed to allow the wheel to rotate in only one direction. The teeth lock against the pawl when the ratchet wheel is rotated in one direction, while rotation in the other direction results in the pawl sliding off the back of the tooth, allowing free rotation. This concept is displayed in Figure 3a.

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Hydraulic brake systems

Design and Testing of Ratcheting, Tension-Only Devices for Seismic Energy Dissipation Systems