Describe the main operating features of any one of the following: Ratchet and pawl, Micrometer, Lathe tailstock. - Leaving Cert Engineering - Question (i) - 2011

The ratchet and pawl mechanism is used to allow a shaft, axle, or pin to rotate in one direction only. The mechanism consists of a ratchet wheel with teeth, designed in such a way that a pawl, which is a lever pivoted on the wheel, engages with the teeth on the ratchet wheel to prevent reverse movement.

When the ratchet wheel rotates in the allowable direction, the pawl slides freely over the teeth, allowing the wheel to turn. However, when an attempt is made to turn the ratchet wheel in the opposite direction, the pawl engages the teeth and prevents this motion.

This mechanism is widely used in applications such as ratchet spanners, fishing reels, and micrometers, where attention to directionality and precision of movement is crucial.