Page 290 - Gear Technology Solutions

20 Shaft Position Tolerances

20.1 Exist Official Standards for Bevel Gear Shaft Position
Tolerances?

For cylindrical gears, tolerances for deviation of shaft center distances and
shaft position of casings are presented in DIN 3964 [1]. The DIN standard co-
vers center distance and shaft inclination tolerances for involute cylindrical
gears. The standard bases on the fact that spur and helical gears with an invo-
lute profile and a straight lead function behave very similar, across a wide
range of modules, helix angles and face widths. The term “center distance in-
sensitivity” of involute gears only refers to the transmission accuracy, which is
not influenced within a certain range of center distance increase. However, if
the center distance reduces, an interference condition will arise from a certain
point on. An increase of center distance as shown in Figure 1 has no impact
on the transmission error between the driving and the driven member, yet it will
create an increased backlash which can cause rattle noise in light load condi-
tions [2].

Figure 1: Center distance insensitivity of involute cylindrical gears

The question, if a similar standard or guideline also exists for bevel gears must
be answered with “no”. The major reason for this is the wide range of different
parameters which influence the sensitivity of a bevel gearset. The following
parameters have a direct influence on the sensitivity and therefore on the

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