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RATCHET & PAWL MECHANISM



INTRODUCTION

·      This type of mechanism is used in producing intermittent rotary motion from an oscillating or reciprocating motion member.
·      The ratchet and pawl mechanism consists of a ratchet wheel and a pawl, as shown in figure.
·      The ratchet consists of a round gear or linear rack with teeth.
·      A pawl is a spring loaded member that engages the teeth of the ratchet the teeth of ratchet is uniform. 


Theory of operation

A ratchet consists of a round gear  or linear rack with teeth. A pawl is a  spring-loaded member that engages the teeth of the ratchet. The teeth are uniform, with each tooth having a moderate slope on one edge and a much steeper slope on the other edge.
When the teeth are moving in the unrestricted (i.e., forward) direction , the pawl easily slides up and over the gently sloped edges of the teeth, with a spring forcing on  it  into the depression between the teeth as it passes the tip of each tooth. When the teeth move in the opposite (backward) direction, however, the pawl will catch against the steeply sloped edge of the first tooth it encounters, 

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