Bevel Gear Classification, Tolerances, and Measuring Methods
|Publication Date:||1 January 2001|
This standard establishes a classification system which may be used to communicate geometrical accuracy specifications of unassembled bevel gearing. It provides a designation system for accuracy of bevel gears and gear pairs. It also provides information on measuring methods and practices. This standard provides the gear manufacturer and the gear buyer with a mutually advantageous reference for uniform tolerances. Eight accuracy grades are defined in this standard, numbered B3 through B10, in order of decreasing precision.
Equations for tolerances and their ranges of validity are provided in 7.2 for the defined accuracy of gearing. In general, these tolerances cover the following ranges:
dT is tolerance diameter (see 3.2);
mmn is mean normal module;
z is number of teeth.
See clause 4 for required and optional measuring methods.
Tolerance tables are provided in annex D for those who prefer to use tables rather than computations for the values of the tolerances that define the accuracy of gearing. These tables are calculated from the equations in 7.2.
Measuring methods and practices
Measuring methods and practices are included to promote uniform measurement procedures (see clause 5). These methods permit the user to conduct measuring procedures which are accurate and repeatable to a degree compatible with the specified accuracy. Experienced personnel, with calibrated instruments in suitable surroundings, are required.
This standard does not apply to enclosed gear unit assemblies, including speed reducers or increasers, gear motors, shaft mounted reducers, high speed units, or other enclosed gear units which are manufactured for a given power, speed, ratio or application.
Gear design is beyond the scope of this standard. The use of the accuracy grades for the determination of gear performance requires extensive experience with specific applications. Therefore, the users of this standard are cautioned against the direct application of tolerance values to a projected performance of unassembled (loose) gears when they are assembled. Refer to the latest AGMA Publications Index for applicable standards.
NOTE: Tolerance values for gears outside the limits stated in this standard should be established by determining the specific application requirements. This may require setting a tolerance smaller than calculated by the formulas in this standard.