Calculation of Bevel Gear Top Land, Slot Widths and Cutter Edge Radii

AGMA 929-B22

AGMA 929-B22


This information sheet supplements ANSI/AGMA ISO 23509 with calculations for bevel gear top land and guidance for selection of cutter edge radius for determination of tooth geometry. It integrates various publications with modifications to include face hobbing. It adds top land calculations for non-generated manufacturing methods. It is intended to provide assistance in completing the calculations requiring determination of top lands and cutter edge radii for gear capacity in accordance with ANSI/AGMA 2003.


[The foreword, footnotes and annexes, if any, in this document are provided for informational purposes only and are not to be construed as a part of AGMA 929-B22, Calculation of Bevel Gear Top Land, Slot Widths and Cutter Edge Radii.]

The Bevel Gearing Committee recognized the need for additional equations to aid in the design of bevel gears. The equations for geometry factors found in the annex of ANSI/AGMA 2003-C10 require detailed information on the proposed cutting tool before a proper calculation can be performed. In addition, the minimum top land thickness is required to aid in determining the maximum case depth allowed on carburized bevel gears. The equations required for these values were not published in AGMA documentation, but could be found, for some cases, in the publications listed in the bibliography of this information sheet. AGMA 929-A06 expands on those equations to include gears manufactured with the face hobbing cutting method.

The equations in this document may yield different values for top land thicknesses and tooth depth at the toe and heel than obtained on commercially available software. The pinion top land thickness is reduced by curvature added to the pinion, a natural consequence of the non-generated gear member having no profile curvature on the teeth. For the gear member, the non-generating process cuts a root line tangent to the gear root cone, a root line that does not wrap around the root cone as in the generated case. This leaves the toe and heel ends of the tooth slots shallow compared to the generated gear case, and the gear tooth space at the ends of the teeth narrower. The non-generated gear is the imaginary generating gear for the pinion. So the pinion teeth, which fit in the non-generated gear tooth slots, are thinner at the ends than their generated gear counterparts.

The cutter edge radii calculated in this document are based on the geometrical conditions as presented. The blades have manufacturing flats. Blade manufacturers have standard blade edge radii and manufacturing tolerances for their products, which should be considered when sourcing non-standard radii. It is recommended to work closely with the blade supplier to ensure design specifications and sourced product specifications are consistent.

AGMA 929-B22 replaces AGMA 929-A06. The main changes include calculations anywhere along the face width instead of just toe, mean, and heel. 

The first draft of AGMA 929-B22 was made in January 2010. It was further developed based on 14FTM13 authored by B. Bijonowski. AGMA 929-B22 was approved by the Technical Division Executive Committee (TDEC) in August 2022.

The AGMA Bevel Gearing Committee wishes to dedicate this new revision to the memory of Ted Krenzer, long time employee of The Gleason Works and the U.S. delegate to ISO TC 60/ WG 13. 


This information sheet provides a set of equations for the calculation of bevel gear top land and guidance on cutter edge radius. It integrates the equations in ANSI/AGMA ISO 23509, Bevel and Hypoid Gear Geometry, and Gleason publication SD3124B, Formulas for Cutter Specifications and Tooth Thickness Measurements for Spiral Bevel and Hypoid Gears, with modifications to include face hobbing, and additions for the top land calculations for non-generated manufacturing methods, to achieve compatibility between publications.

It is intended to provide assistance in completing the calculations requiring determination of top lands and cutter edge radii in ANSI/AGMA 2003, Rating the Pitting Resistance and Bending Strength of Generated Straight Bevel, Zerol Bevel and Spiral Bevel Gear Teeth.

Annexes are provided for additional related information and calculation examples.

Pages: 71

ISBN: 978-1-64353-120-5

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