Re: How does a ratchet wrench work?

A ratchet is a rather clever device used to make sure that a driven shaft
turns in one direction only. There are many applications and variations
(wrenches, clutches, window shades, etc.) but they all basically consist
of a disk that is cut like a gear, except that the teeth are cut with a
flat (radial) side and a ramped side. (This is actually an application of
a lever). The other component is called a "pawl" which fits into the teeth
on the ratchet. When the ratchet turns in the direction of the ramped side
of the teeth, the shaft rotates and the pawl simply "bounces" over the
teeth. When you try to rotate in the opposite direction, the pawl
encounters and blocks the flat side of the teeth and prevents rotation.
A good explanation and drawing of a ratchet can be found in the book THE
WAY THINGS WORK, p 79., by David MaCaulay.
I hope this helps.
fjc

Frederick J. Carranti, P.E.
Institute for Manufacturing Engineering
151 Link Hall
Syracuse University