Page 48 - Gear Technology Solutions

Figure 7: Ease-Off represented with ISO-lines

Such an ISO-line graphic is a mathematically correct interpretation of the
crowning or mismatch. However, it is a miss-perception to believe that the
same useful information can be retrieved from the ISO-line graphic as can be
seen in an Ease-Off graphic. It would be required to use 50 to 200 ISO-lines to
capture all important nuances of the Ease-Off but the observer would still not
be able to capture all the details and visualize the effects of high load or shaft
and housing deflections.

3.6 Summary

The Ease-Off appears to be the most efficient way to judge the flank topogra-
phy design of a bevel gearset. Modern thinking gear engineers have adopted
Ease-Off as their most important tool, when designing and optimizing bevel
and hypoid gears. In connection with the contact pattern and the motion
transmission graph, an optimization for high strength and low noise is easier
and faster than in the past. One stunning question is why in the cylindrical gear
world, the technology of Ease-Off and tooth contact analysis was never found
of interest. Also, in metrology, the measurement of a surface grid and the
presentation of a deviation topography (similar to the Ease-Off) is, in the bevel
gear technology, a standard which has been used for several decades. In the
cylindrical field there are some shy attempts to try out surface grid measure-
ments instead of profile and lead scans. There would be a lot to gain from the
synergies between cylindrical and bevel gear technology, if these two “worlds”
would finally come together.

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