Page 65 - Gear Technology Solutions

®
Today’s CNC controlled Phoenix free form machines have the Helical Motion
capability automatically by their interpolated axes movement.

4.7 Why is Conjugacy not Desirable for Real World Applications?

In 1926 Ernest Wildhaber [3, 8] was the first to propose applying surface
crowning on hypoid gears. Wildhaber acknowledged that the slightest devia-
tions in the gear housing and in the building position as well as deflections af-
fected by load and heat will cause edge contact with peak stress levels of a
multiple of the allowable values the gearset had been designed for. The conju-
gate gearset used for the TCA in Figure 11 was repeated with realistic dis-
placement values of 50mm offset, 50mm pinion cone and 30’ of shaft angle
change. The results in Figure 14 show warped and tilted Ease-Offs and se-
vere edge contact on heel and top. This edge contact will cause noisy opera-
tion followed by pitting and tooth fracture.

Figure 14: TCA of conjugate hypoid set from Figure 11 with displacements

The theoretically conjugate hypoid set will depart from fulfilling any of the fun-
damental gearing laws in case of the smallest gearbox inaccuracies or deflec-

50