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20.3 Recommended Backlash and Tolerances

The Gleason backlash recommendation and its tolerance is not linked to a
gear quality class. In Table 1, the backlash ranges have originally been de-
fined for applications with medium speed and oil sump lubrication. Depending
on the kind of transmission and the field of application, a manufacturer can de-
viate from the recommended values, utilizing data from their own testing.
Backlash ranges are given from module 0.21mm (DP 120/inch) up to module
20.32mm (DP 1.25/inch). The table is a conversion from the initial Imperial
units, which explains the unusual decimal fraction of the SI units. For bevel
and hypoid gears, backlash is the most important basis of all shaft position tol-
erances. Common sense tells the gear engineer that each dimensional devia-
tion, which impacts the shaft positioning within the backlash tolerances, is
permissible.

Table 1: Backlash ranges for bevel and hypoid gears,
depending on the module

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