Ratchets and pawls are mechanical assemblies that are used to transmit intermittent rotary movement, or even to permit a shaft to rotate in one direction however, not the other. Ratchets and pawls are often made of:
steel
stainless steel
cast iron
brass
other metal materials
Features
Ratchets are Pawls For Ratchets Wheel occasionally called ratchet tires because they contain a rotating equipment or rack with angled teeth. Pawls, which are occasionally misidentified as ratchets, are thin protrusions that rest against a ratchet to restrict its movement. When the ratchet is definitely rotated in one path, the pawl is elevated and moves smoothly between your angled the teeth. When the ratchet’s rotation stops, the pawl rests between the the teeth and makes a clicking sound. 
Ratchets and pawls that permit rotation in only one direction cause the pawl and the teeth to clash if the ratchet is turned the opposite way.
Pawl
Applications
Applications for these single-direction devices include:
turnstiles
spanners
winders
jacks
The action of a ratchet could be either harsh or smooth, based on the configuration of the ratchet teeth and pawl.
