Page 103 - Gear Technology Solutions

During the servicing of a gearset with a hunting tooth ratio it is not of any use
to mark a tooth and the slot it meshes with because the “tooth hunting” will put
the gears back for an equally optimal performance as before removal, inde-
pendent from the orientation of the gears.

7.7 Summary

A hunting tooth ratio is already established, if the two tooth counts have no
common denominator. If the pinion tooth count is a prime number and the gear
tooth count is for example twice of that, then no hunting tooth condition exists.
If both tooth counts are prime numbers (co-prime ratio), then the hunting tooth
condition exists, however, it is difficult to achieve the correct ratio and find two
prime tooth counts to realize this ratio. In most cases, it is easy enough to real-
ize the correct ratio (within a given Tolerance) by avoiding a common denomi-
nator.

The hunting tooth condition reduces runout and single flank amplitudes of
lapped gearsets during the lapping process. The break-in of lapped gears only
polishes the flank surfaces but has little influence on runout and single flank
error.

Ground gears, especially in power transmission applications, take a great ben-
efit from a hunting tooth ratio. The break-in reduces runout and single flank
error and a noise reduction can be noticed. Also, the surface polishing action
effect during the first 300 miles of driving with a vehicle is more favorable if a
hunting tooth ratio is present. The “natural” tooth polishing of hunting tooth ra-
tios during break-in improves the efficiency of a gearset.

7.7 Literature

[1] Elaine “Hunting Tooth”, Everything2, The Media LLC,
www.everything2.com, 2020

[2] N.N. “Gleason Bevel and Hypoid Gear Design”
Company Publication, The Gleason Works, Rochester, New
York, SD 3041A 65C DBP, 1956, Page 22

88