Gear Handbook - Gear Classification, materials and measuring methods for bevel, hypoid, fine pitch, wormgearing and racks only as unassembled gears.

AGMA 390.03A

CAUTION: This standard is obsolete and should not be used in the design, manufacture, or inspection of gears, gear products, or flexible couplings.


This Standard for bevel, hypoid, fine pitch wormgearing and racks correlates gear quality levels with gear tooth tolerances. It provides information on gear measuring methods and practices. It provides guidance on specifying quality levels and materials, and also contains information on tooth contact patterns and backlash.


[The foreword, footnotes, and appendices, if any, are provided for informational purposes only and should not be construed as a part of American Gear Manufacturers Association Standard 390.03a, Gear Handbook - Gear Classification, Materials and Measuring Methods for Bevel, Hypoid, Fine Pitch Wormgearing and Racks Only as Unassembled Gears.]

This Handbook provides tolerances for different quality levels from Q3 through Q 14 for unassembled bevel and hypoid gearing, racks and wormgearing. It further describes methods and practices for measuring the various gear elements for which tolerances are provided.

The purpose is to present a common basis for specifying quality, and for the procurement of unassembled gears. It is not a design manual for determining the specific quality level for a given application. It is not intended for use as a reference in the procurement of enclosed drives.

AGMA 390.03 was published in 1973, and revised in 1980, as a consolidation and updating of several withdrawn AGMA publications including:

  • AGMA 235.02 (1966), Information Sheet for Master Gears
  • AGMA 236.04, Inspection of Fine Pitch Gears
  • AGMA 239.0lA (1965), Measuring Methods and Practices for Control of Spur, Helical and Herringbone Gears
  • AGMA 390.02 (1964), Gear Classification Manual (Originally AGMA 390.01)

In 1987 the AGMA Gear Classification and Handbook Committee completed a partial revision of AGMA 390.03. This revision contained the standards for spur, helical and master gears, added application detail, formulas for gear tolerances in Metric terms, and added tolerance tables in Metric notation. This revision was approved by the AGMA membership in January 1988, and by the American National Standards Institute (ANSI) in March 1988. The revision was published as ANSI/AGMA 2000-A88, Gear Classification and Inspection Handbook.

This Standard, 390.03a, contains the information from AGMA 390.03, dated 1980, (including the 1983 errata) that was not included in 2000-A88. This information remains unchanged. Included in 390.03a are tolerance tables and measuring methods for bevel and hypoid gears, racks and wormgearing, and some data that is common to both AGMA 390 and AGMA 2000.

The Table of Contents for this Standard, 390.03a, contains the complete listing as it appeared in 390.03 before the current edition. Page numbers in the Table of Contents, for the Sections that have been removed and included in AGMA 2000-A88, have been replaced with asterisks with footnotes for explanation. Page numbers in the text of the Standard are unchanged. Where pages have been deleted for inclusion in AGMA 2000-A88, a page has been inserted explaining the deletion in order to preserve continuity.

Part 1, General Information, has been left intact even though some material does not apply to Bevel, Hypoid, Fine Pitch Wormgearing and Racks. This information was revised for spur, helical and master gears in AGMA 2000-A88.