In design of all kinds of
power transmission gearing, also applicable to
design of chain or toothed
belt drives.
A "hunting tooth" is used to avoid gear ratios where the tooth count of one
gear is an exact multiple of a gear it mates to (e.g. ratios 1:1, 2:1, 3:1 ...).
The reason for avoiding integer gear ratios is that in such a design each tooth
of the smaller gear always contacts exactly the same tooth or teeth in the gear
it mates to. This in turn will cause accelerated wear, usually into an oval
shape.
Thus if designing an (approximately) 2:1 gear ratio, the designer uses
gears with 49 and 24 teeth respectively, then every tooth on each gear comes
in contact with on it's mating gear. This in turn causes minor variations in
wear to be propagated across all teeth.
In sprocket design, it is desirable to design for the chain or belt having
a number of links which should not be evenly divisible by the number of
teeth in any sprocket,