Page 270 - Gear Technology Solutions

an increased low load contact ratio. In Figure 20, the zero load contact ratio is
1.70, compared to 1.0 in all cases of conventional, parabolic motion graphs.
The double wave maintains the contact pattern under load better than a com-
pletely conjugate flank center. Bevel gearsets with an Ultimate Motion Graph
are considered to have favorable noise, vibration and harshness (NVH) prop-
erties.

Figure 20: The Ultimate Motion Graph - UMC-Ultima

The load sharing ratio indicates how the transmitted load of a gearset is
shared between neighboring tooth pairs. A vertical line at the center of the dia-
grams in Figure 21 shows the maximal load sharing contribution of one pair of
teeth (green graphs). The two neighboring pairs (blue and red graphs) contrib-
ute with lower loads. The readings at the intersection points with the three
graphs have to add up to 100%. In the example in Figure 21, three pairs of
teeth contribute to the load transmission. Depending on the basic design of a
gearset, four or even more pairs of teeth can be involved in the load transmis-
sion at any time (for example SRH gearsets).

The example in Figure 21 reflects an operating mode with 50% of the rated
load. The conventional crowning to the left requires that each tooth pair trans-
mits a maximum of 80% of the input load, while the neighboring tooth pairs
transmit only 10% each.

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