Kigar Falk Corporation Vice Chairman: The following values are suggested for the mesh alignment correction factor: The stress cycle factor adjusts the allowable stress numbers for design lives other than cycles. This deterioration of the surface of the material is generally thought to occur because of excessive Hertzian stresses due to influences from gear loading, material and its heat treatment, the type of lubricant, and degree of lubrication. Heat Treatment of Steel Gears July 15, The equations presented are more accurate than any other published equations found by the author in other literature. For the purpose of this standard, nL, the number of stress cycles is defined as the number of mesh contacts, under load, of the gear tooth being analyzed. AGMA also provides information to help you select the application factor KA for specific turbo-driven applications and other useful notes about this type of gear lubrication arrangement etc. Rim thickness factor, KB.
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It is not intended to assure the performance of assembled gear drive systems. These fundamental rating formulas are applicable for rating the pitting resistance and bending strength of internal and external spur and helical involute gear teeth operating on parallel axes.
The formulas evaluate gear tooth capacity as influenced by the major factors which affect gear tooth pitting and gear tooth fracture at the fillet radius. The knowledge and judgment required to evaluate the various rating factors come from years of accumulated experience in designing, manufacturing, and operating gear units.
Empirical factors given in this standard are general in nature. AGMA application standards may use other empirical factors that are more closely suited to the particular field of application. This standard is intended for use by the experienced gear designer, capable of selecting reasonable values for the factors.
It is not intended for use by the engineering public at large. Exceptions The formulas of this standard are not applicable to other types of gear tooth deterioration such as plastic yielding, wear, case crushing and welding. The formulas of this standard are not applicable when any of the following conditions exist: Damaged gear teeth. Interference exists between tips of teeth and root fillets.
Teeth are pointed. Backlash is zero. Undercut exists in an area above the theoretical start of active profile. The effect of this undercut is to move the highest point of single tooth contact, negating the assumption of this calculation method. However, the reduction in tooth root thickness due to protuberance below the active profile is handled correctly by this method.
The root profiles are stepped or irregular. The YJ factor calculation uses the stress correction factors developed by Dolan and Broghamer . These factors may not be valid for root forms which are not smooth curves. For root profiles which are stepped or irregular, other stress correction factors may be more appropriate.
Where root fillets of the gear teeth are produced by a process other than generating. Scuffing criteria are not included in this standard. This information is provided for evaluation by users of this standard, with the intent to include a scuffing evaluation method in a future version of this standard. Design considerations to prevent fractures emanating from stress risers on the tooth profile, tip chipping, and failures of the gear blank through the web or hub should be analyzed by general machine design methods.
The purpose of this standard is to establish a common base for rating various types of gears for differing applications, and to encourage themaximum practical degree of uniformity and consistency between rating practices within the gear industry. It provides the basis from which more detailed AGMA application standards are developed, and provides a basis for calculation of approximate ratings in the absence of such standards. The formulas presented in this standard contain factors whose values vary significantly depending on application, system effects, gear accuracy, manufacturing practice, and definition of gear failure.
Proper evaluation of these factors is essential for realistic ratings. This standard is intended for use by the experienced gear designer capable of selecting reasonable values for rating factors and aware of the performance of similar designs through test results or operating experience.
In AGMA Values for factors assigned in standards prior to that were not applicable to Metallurgical quality factors for steel materials were defined, establishing minimum quality control requirements and allowable stress numbers for various steel quality grades.
Additional higher allowable stress numbers for carburized gears were added when made with high quality steel. A new rim thickness factor, KB, was introduced to reduce allowable bending loads on gears with thin rims. Material on scuffing scoring resistance was added as an annex. It also reflects a change to clause 10, dealing with the relationship between service factor and stress cycle factor. Editorial corrections were implemented to table 8, figure 14 and table E, and style was updated to latest standards.
This AGMA Standard and related publications are based on typical or average data, conditions, or applications. The Association intends to continue working to update this Standard and to incorporate in future revisions the latest acceptable technology from domestic and international sources. It was approved as an American National Standard on December 28, Suggestions for improvement of this standard will be welcome.
At the time of development, the editions were valid. All publications are subject to revision, and the users of this standard are encouraged to investigate the possibility of applying the most recent editions of the publications listed. AGMA Discounted member price:
American Gear Manufacturers Association