The two profiles (sides) of a gear tooth are functionally different for most
gear drives. The workload on one profile is significantly higher and/or is applied for
longer periods of time than for the opposite one. The design of the asymmetric
tooth shape reflects this functional difference.
The design intent of asymmetric gear teeth is to improve the performance of
the primary contacting profile by degrading the performance of the opposite
profile. The opposite profile is typically unloaded or lightly loaded during
relatively short work period. The "improved performance" of the primary
Increased load capacity
Reduced Weight & Size
The degree of asymmetry and drive profile selection for these gears depends
on the application. Asymmetric profiles make it possible to manage tooth
stiffness and load sharing while keeping a desirable pressure angle and
contact ratio on the drive profiles.
Gears with asymmetric teeth should be considered for gear systems that require
extreme performance like aerospace applications. They are also applicable
for mass production transmissions where the share of the tooling cost per
one gear is insignificant, like in automotive gears. The most promising
application for asymmetric profiles is with molded gears and powder metal
gears. Molded gears require custom tooling anyway and asymmetric tooth
profiles do not increase the tooling or production costs.
Using the direct design approach for asymmetric gear teeth is easier than for
conventional gears. Asymmetric gear design is not constrained by standardized
tooling and the tool based design approach used for conventional gears.
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