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.
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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