Discover

In mechanical engineering a 'ratchet' is a device used to restrict motion in one direction. This sort of behavior is useful in many areas, such as in turnstile, spanners (where rotation in confined surfaces can be achieved easily), winders, jacks, hoists and others.

Contents

Ratchet and pawl

See also

External links

Ratchet and pawl

Ratchets work generally by having a form of gearwheel or rack (as in Rack and pinion) that, instead of having regular teeth, have teeth set off at an angle, and a stiff, thin protrusion called the pawl [1] (''a'') or the ''click''that rests against the gearwheel (''b''). When the gearwheel is rotated in one direction, the protrusion raises and clicks back in place. Because of the shape of the gearwheel it is difficult to push the protrusion back and over the tooth of the gear.
Alternatively, this gearwheel can be set in a molding shaped to admit rotation of this gearwheel in one direction only. If the gearwheel is rotated backwards the molding and the teeth will clash.

See also

★ freewheel

External links

★ An animated display of ratchet mechanism