This standard establishes the calculation procedures for determining specification limits for external and internal cylindrical involute gearing when the desired tooth thickness is known. This standard also shows the relationships between backlash and the tooth thickness, center distance, and tooth deviations in a pinion and gear mesh.

Measurement methods included in standard

Equations and procedures are included for the following tooth thickness measuring methods:

– measurement by pitch or index;

– measurement with a master gear on a double flank tester;

– measurement with a master gear on a single flank tester;

– span measurement;

– measurement over or between balls or pins;

– measurement with measuring blocks;

– chordal measurement.

Types of gears

This standard applies to the following types of gears:

– external and internal involute spur gears;

– external and internal parallel axis involute helical gears;

– involute worms and other crossed-axis helical gears;

– spur and helical racks;

– involute sector gears, spur, and helical.

Dimensional and material limitations

The equations in this standard apply to gears of all sizes and materials, and to all manufacturing methods. However, practical considerations and availability of test equipment can preclude the use of some methods on some sizes of gears.

Some methods may not be appropriate for compliant materials if the use of the tooth thickness measuring tools and techniques result in deformation of the gear teeth.

Exclusions

The determination of design tooth thickness for a given application is beyond the scope of this standard.