Page 292 - Gear Technology Solutions

Angular bevel gears have a shaft angle not equal to 90°. As the shaft angle
gets closer to zero the bevel gearset behaves more like a cylindrical gearset.
In this case, the tolerances for cylindrical gears apply. As the shaft angle gets
closer to 180° the bevel gearset behaves more like a clutch and the tolerances
of clutches can be applied.

20.2 Bevel and Hypoid Gear Sensitivity Evaluation

Bevel and hypoid gearsets have very individual displacement behavior, which
is why the national and international standards were not able to establish a set
of tolerances which is generally applicable. The bevel and hypoid gear calcula-
tion programs use the so called “V-H-Check”, introduced by Gleason in 1965,
in order to express the sensitivity of a bevel gearset. The shaft displacement in
the directions E (offset), P (pinion axial), G (gear axial) and ALPHA (shaft an-
gle) are sufficient for capturing the axis deflections in three linear and three
angular directions (Figure 2). A set of deflections fa, fbgear and fbpinion can be
converted into an equivalent set of deflections E*, P*, G* and ALPHA* as
demonstrated in Figure 3. For this reason, the tolerances fbgear and fbpinion do
not exist in reality.

Figure 3: Transformation of 6 deflections into 4 deflections

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